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7 


\^a:--<^'''- 


.G-  573 


WORKS 


OP   THE 


CAVENDISH     SOCIETY. 


FOUNDED    1846, 


HAND-BOOK 


CHEMISTRY. 


BY 

LEOPOLD    GMELIN, 

FROnSSOB  OT  CHXHXSTKT  IN  THX  ninVXMIT7  Of  RSIDKLBSXO. 

AND  MEMBER  07  VARIOUS  LEARNED  80CIBTIBS  IN  BERLIN,  BONN,  CATANIA,  DRESDEN,  nsnURG, 

FRANKPORT,  GdlTINOEN,  HALLE,  HAMBI7RO,  HANAU,  HBIDELBERO,  JA8ST,  LONDON, 

MABBUBOt  XUNICH,  PABI8,  PBTBBSBVBaH,  TIEN  HA,  AND  WETTEBAU. 


VOL.  II. 

NON-METALLIC  ELEMENTS. 

TIIAJT8I.ATED  BT 

HENRY  WATTS,   B.A..  F.C.S. 

ASSISTANT    IN    THB    BIRKBBCX    LABOBATOBT,    UNIVEBSITT    COLLBOB,    LONDON. 


LONDON: 
PRINTED  FOR  THE  CAVENDISH  SOCIETY. 

MDCCGXLIX. 


honoon: 

PRINTJU)  BV  HARRTHON  AND  M>^f- 
«T.  MART'N'S    LANR. 


CONTENTS  OP  VOL.  11. 


Part  II.    Special  Chemistry  (continued). 


Sectiok  II.    CHEMISTRY  OF  PONDERABLE  BODIES. 

Pag« 
OlaaBification  of  Elements        1 


First  Division.    INORGANIC  CHEMISTRY. 

Compounds  of  the  First  Order      2 

Componnds  of  the  Second  Order         5 

Compounds  of  the  Third  Order     13 

Compounds  of  the  Fourth  and  Fifth  Orders              14 

Theory  of  Salts       14 


SuBDiTisiON  L    METALLOIDS. 

Chapter  I.    OXYGEN. 

List  of  Memoirs,  &o.  relating  to  Oxygen        19 

History,  Sourcesf,  Preparation        20 

Collection  and  Preservation  of  Gkbses 23 

Combustion 24 

COMPOUKDS  OF   OXTOKK          38 


Chapter  IL    HYDROGEN. 

Memoirs,  &c.  41 

History  42 

Sources  and  Preparation     43 

139540 


VI  CONTENTS. 


Pag« 


Compounds  or  HrDRooEx. 

Hydrogen  and  Oxygen. 

Water  45 

Peroxide  of  Hydrogen 73 

Suboxide  of  Hydrogen         79 

Other  Compounds  of  Hydrogen         70 


Chapter  UI.    CARBON. 

Memoirs,  &c.      81 

History        81 

Sources 82 

Prepuation  83 

Properties         84 

Com  POUNDS  of  Carbok. 

Carbon  and  Oxygen. 

Carbonic  Oxide 87 

Carbonic  Acid  89 

Other  Componnds  of  Oaibon  94 


Chapter  IV.     BORON. 

MemoirBy  History,  Sources,  and  Preparation 96 

Properties 96 

Compounds  of  Boron. 

Boron  and  Water 96 

Boron  and  Oxygen. 

BoracicAcid        97 

Boron  and  Hydrogen         100 


Chapter  V.    PHOSPHORUS. 

Memoirs,  &c.  100 

History 102 

Sources  and  Preparation     103 

Properties         106 

Compounds  of  Phosphorous. 

Phosphorus  and  Oxygen. 

Phosphoric  Oxide  110 

Hypophosphorous  Acid         113 

Phosphorous  Acid  115 

Phosphoric  Acid        121 


CONTENTS.  vii 

Page 
Phosphorus  aud  Hydrogen. 

Solid  PhoGfphide  of  Hydrogen    135 

Phosphuretted  Hydrogen  gas          136 

if*  I'iqnid  Phosphide  of  Hydrogen             148 

Phosphorus  and  Carbon            149 

Phosphorus  "with  Phosphorus         160 

Metallic  Phosphides          ...,                 160 


Chapter  VI.    SULPHUR. 

Memoirs^  &c  161 

History 163 

Sources  and  Preparation     164 

Properties  166 

COMPOUITDS  OF   SULPHUB. 

Sulphur  and  Oxjgen. 

Hyposulphnrous  Acid     160 

If.  Pentathionic  Acid     162 

%  Tetrathionio  Add  „ 164 

Trithionic  Acid         167 

Sulphurous  Acid 168 

Hyposulphuric  Acid 174 

Sulphuric  Acid 176 

Sulphur  and  Hjdrogen. 

Hydrosulphurons  Acid         193 

Hydrosulphurio  Add      196 

Sulphur  and  Carbon. 

Bisulphide  of  Carbon  200 

Sulphuretted  Bisulphide  of  Carbon       205 

Sulphuretted  Charcoal  206 

Hydro-sulphocarbonio  Add        206 

Sulphur  and  Boron  206 

Sulphur  and  Phosphorus        207 

Sulphides  of  Phosphorus       207 

If.  I.  Disulphide         209 

If.  IL  Protosulphide        212 

If.  III.  Tersulphide 215 

if.  IV.  Pentasulphide       217 

f .  V.   Persulphide     218 

Phosphuretted  Bisulphide  of  Carbon 219 

Sulphate  of  Phosphuretted  Hydrogen     220 

^.  Sulphoxyphosphoric  add        ...  220 

Metallic  Sulphides      221 


▼m  CONTENTS. 

Page 
CuAPTEm  VII.    SELENIUM. 

Menunn,  &c.,  Historj,  Sooroes           231 

Preparation       233 

PropertieB 236 

COMPOUITBS  OF   SeLEKIUM. 

Seleniam  and  Oxjgen. 

Selenic  Oxide         236 

Seleiiioiu  Add 236 

Selenic  Acid....        ....        ....        ....        ....        ....        ....        ....  239 

Selenium  and  Hydrogen. 

Hydroselenic  Add     241 

Selenium  and  Phoephoros       242 

Seleninm  and  Sulphur      243 

MetaUio  Selenides       244 

Chaptee  VIIL    IODINE. 

MemoirBy&c 246 

HiBtory,  Sources      247 

Preparation        249 

Properties 2fi0 

CoMPouKDs  OP  Iodine. 

Iodine  and  Water             261 

Iodine  and  Oxygen. 

Iodic  Oxide          261 

lodousAdd 262 

Iodic  Acid            263 

Periodic  Add            269 

Iodine  and  Hydrogen. 

HydriodouB  Acid 261 

Hydriodic  Acid         261 

Iodine  and  Boron        264 

Iodine  and  Phosphorus     266 

Iodine  and  Sulphur     267 

Iodine  and  Selenium         268 

Metallic  Iodides          269 


Chapter  IX.    BROMINE. 

Memoirs,  &c 271 

History,  Sources,  &c 272 

Preparation       273 

Properties    276 


CONTENTS.  IX 

Page 
C0MPOUKD8  OF  Bromine. 

Bromine  and  Water         276 

Bromine  and  Oxygen. 

HypobromouB  Acid        276 

Bromic  Add            277 

Bromine  and  Hydrogen. 

Hydrobromons  Add       279 

Hydrobromic  Add    279 

^.  Bromine  and  Boron. 

Bromoborado  Add         281 

Bromine  and  PhoephoniB 282 

Bromine  and  Bolphur 283 

Bromine  and  Selenimn     284 

Bromine  and  Iodine    286 

Metallic  Bromides            286 

Chapteb  X.    CHLOBINR 

Memoii8>  &c.          288 

Hiatoiy 289 

Soorcee  and  Preparation    290 

Properties          292 

Compounds  of  Ghlobike. 

Chlorine  and  Water 293 

Chlorine  and  Oxygen. 

Hypochlorous  Add 294 

%.  ChloroQB  Add      306 

Hypochloric  Acid      309 

Chloric  Acid        812 

Perchloric  Add 316 

Chlorine  and  Hydrogen. 

Hydrochloric  Acid          319 

Chlorine  and  Carbon         326 

Phosgene          326 

Chlorine  and  Boron          327 

Chlorine  and  Phosphorns. 

Terchloride  of  Phosphorus         328 

Pentachloride  of  Phosphorns            329 

^.  Oxychloride  of  Phosphorns      330 

Chlorine  and  Sulphur. 

Dichloride  of  Sulphur           331 

Protochloride  of  Sulphur            3.33 


X  CONTENTS. 

Page 

Bichloride  and  Terchloride 334 

Chlorosolphide  of  FhoflphoniB    334 

if.  ddorondphide  of  Carbon 335 

Carbonate  of  Bichloride  of  Sulphur      337 

^.  Carbonate  of  Protochloride  of  Sulphur      339 

Sulphate  of  Hydrochloric  Add 341 

Sulphate  of  Pentachloride  of  PhosphoruB 341 

Bisulphate  of  Terchloride  of  Sulphur     342 

Pentasulphate  of  Terchloride  of  Sulphur    343 

f.  Sulphate  of  Bichloride  of  Sulphur       345 

Chlorine  and  Selenium. 

Chloride  of  Selenium            345 

Sulphate  of  Chloride  of  Selenium        346 

Chlorine  and  Iodine. 

Protochloride  of  Iodine        346 

Terchloride  of  Iodine     348 

Sulphate  of  Iodide  of  Sulphur         350 

Chlorine  and  Bromine      350 

Metallic  Chlorides      351 

Antichlorigtic  Theory              356 


Chapter  XI.    FLUORINE. 

Memoirs,  &c.           358 

History 358 

Sources  and  Preparation    359 

Compounds  of  Fluokike. 

Fluorine  and  Hydrogen. 

Hydrofluoric  Acid    360 

Fluorine  and  Boron. 

Terfluoride  of  Boron       362 

Fluoboric  Add          363 

Hydrofluoboric  Acid      364 

Fluorine  and  Phosphorus 364 

Fluorine  and  Sulphur             364 

Fluorine  and  Selenium     365 

Metallic  Fluorides  365 


Chapter  XII.    NITROGEN. 

Memoirs,  &c 368 

History        370 

Sources 371 


CONTENTS.  XI 

Page 

Preparation 372 

Properties          372 

CoMPOuHDs  OF  Nitrogen. 

Nitrogen  and  Water        373 

Nitrogen  and  Oxygen. 

Nitrons  Oxide     373 

Nitric  Oxide 377 

Nitrous  Add        380 

Hyponitric  Acid        382 

Nitric  Acid           386 

Atmospheric  Air       402 

Nitrogen  and  Hydrogen. 

Amidogen            416 

Ammonia       ....        ....         ....         ....         ....         ••••         ....         ...  416 

Ammoninm          ....         ....         ....         ....         •••.         ...•         ....  428 

Nitrogen  and  Carbon. 

Carbonate  of  Ammonia        430 

Nitrogen  and  Boron. 

Borate  of  Ammonia        435 

Nitrogen  and  Phosphoms. 

Phosphide  of  Nitrogen          436 

Phosphamide       438 

Biphosphamide          439 

Phosphoric  Oxide  with  Ammonia         440 

Hypophosphite  of  Anmionia            441 

Phosphite  of  Ammonia 441 

Ordinary  Phosphate  of  Ammonia    441 

Pyrophosphate  of  Ammonia       442 

Metaphosphate  of  Ammonia            442 

Nitrogen  and  Snlphnr. 

Sulphide  of  Nitrogen      442 

Sulphite  of  Nitric  Oxide      444 

Sulphate  of  Nitric  Oxide            446 

Mono-hydrosulphate  of  Ammonia 461 

Bi-hydrosulphate  of  Ammonia ....  462 

Hypo-hydrosulphate  of  Ammonia 462 

Hydrosulphite  of  Ammonia             462 

Hypo-hydrosulphite  of  Ammonia           463                   j,/*^^ 

Hyposulphite  of  Ammonia         464 

Sulphamide ^^ 

Anhydrous  Bi-Sulphite  of  Ammon        466 

Sulphite  of  Ammonia           ^67 

Hyposulphate  of  Ammonia         468 


XU  CONTENTS. 

Page 

Anhydrous  Sulphate  of  Ammon      468 

Deliquescent  Sulphate  of  Ammon         461 

Sulphate  of  Ammonia          462 

Sulphocarbonate  of  Ammonia    462 

Hydrosnlphocarbonate  of  Ammonia            463 

Sulphophosphite  of  Ammonia    463 

Nitrogen  and  Selenium. 

Mono-hydroseleniate  of  Ammonia 464 

Bi-hydioeeleniate  of  Ammonia 464 

Selenite  of  Ammonia            464 

Nitrogen  and  Iodine. 

Iodide  of  Nitrogen?        466 

Iodide  of  Ammonia?             467 

Hydriodate  of  Ammonia            468 

Hydriodite  of  Ammonia       468 

lodate  of  Ammonia         469 

Nitrogen  and  Bromine. 

Bromide  of  Nitrogen            469 

Hydrobromate  of  Ammonia       469 

Bromate  of  Ammonia          469 

Ammonio-terbromide  of  Phosphorus    470 

Nitrogen  and  Chlorine. 

Chloride  of  Nitrogen            47O 

Chlorophosphide  of  Nitrogen     474 

Chlorosulphide  of  Nitrogen              476 

Aqua>regia           476 

Hydrochlorate  of  Ammonia             478 

Hypochlorite  of  Ammonia         479 

Chlorite  of  Ammonia            479 

Hypochlorate  of  Ammonia         460 

Chlorate  of  Ammonia            480 

Perchlorate  of  Ammonia            480 

Chloro-carbonate  of  Ammonia         480 

Chloro-borate  of  Ammonia        481 

Ammonio-tercMoride  of  Phosphorus           481 

Ammonio-pentachloride  of  Phosphorus             482 

Ammonio-dichloride  of  Sulphur          ....  483 

Ammonio-protochloride  of  Sulphur       484 

Carbonate  of  Ammonio-chloride  of  Sulphur           486 

Sulphate  of  Ammonio-chloride  of  Sulphur       487 

Ammonio-chloride  of  Iodine            487 

Nitrogen  and  Fluorine. 

Hydrofluate  of  Ammonia            488 

Ammonio-flnoride  of  Boron             489 

Fluoborate  of  Ammonia             489 


CONTENTS.  xm 

Page 
Nitrogen  with  Nitrogen. 

Nitrite  of  Ammonia             489 

Nitrate  of  Ammonia       490 

Sulphite  of  Nitrio  Oxide  and  Ammonia      492 

Gomponnd  of  Ammonio-ohloride  of  Snlphnr  with  Ammonio-snI- 

phide  of  Nitrogen 493 

Metallic  Nitrides 494 


APPENDIX. 

Tahle  I.  Gonvenion  of  French  into  English  measnres  497 

Table  U.  Barometer  scale  in  millimetres  and  inches        499 

Table  III.  Thermometer  scales,  Centigrade  and  Fahrenheit 600 

Table  IV.  Tension  of  Oases 693 


EXPLANATION  OF  THE  SHORT  TABLES  WHICH  OCCUR  IN 
THIS  AND  THE  SUBSEQUENT  VOLUMES. 


The  table  which  gives  the  composition  of  nitric  oxide  (p.  377)  may  serve  as  an 
example : 

Calcalation.  d.  d.  d, 

a.  b,  c.  H.  Davy.       Dalton.        Berzelius. 

N      14  46-«7  42-3  42  46754 

20     16  53-33  57-7  58  53*246 

NO«   30  100-00  1000  100  100000 

/.  g.                h. 

Vol.  8p.  gr.            Vol.  sp.  gr. 

Nitrogen  gas 1     0-9706  =     \    04853 

Oxygen  gas    1     1-1093  =     i     0-5546 

Nitric  oxide  gas 2     2-0799     =     1     1-0399 

a.  The  constituents  of  nitric  oxide  are  nitrogen  and  oxygen ;  and  they  are  most 
probably  united  in  the  proportion  of  1  atom  of  nitrogen  to  2  atoms  of  oxygen. 

b.  According  to  the  most  accurate  experiments  hitherto  made  on  the  propor- 
tions by  weight  in  which  nitrogen  and  oxygen  combine  with  each  other  and  with 
other  bodies,  the  atomic  weight  of  nitrogen  is  estimated  at  14,  that  of  oxygen  being 
assumed  a  8,  and  that  of  hydrogen  =  1.  Moreover,  since  the  atomic  weight  of  a 
compound  is  found  by  adding  together  the  atomic  weights  of  its  element,  the 
atomic  weight  of  nitric  oxide  must  be  14  +  2  .  8  »  30. 

c.  If  30  parts  of  nitric  oxide  contain  14  nitrogen  and  16  oxygen,  it  follows  that 
100  nitric  oxide  will  contain  46*67  nitrogen  and  63*33  oxygen. 

dy  dy  d.  The  analyses  of  different  chemists  here  given,  calculated  to  100  parts, 
serve,  on  the  one  hand,  to  establish  the  correctness  of  the  calculation  c,  made 
upon  a  particular  sto'ichiometrical  hypothesis,  and,  on  the  other  hand,  are  them- 
selves confirmed  by  that  calculation :  viewed  in  this  light,  the  analysis  of  Berzelius 
appears  to  be  more  correct  than  that  of  Davy  or  Dalton. 

e,  Graseous  bodies  likewise  exhibit  great  simplicity  and  regularity,  when  their 
composition  is  estimated  by  volume.  (I.  64—67-) 

/.  In  the  case  under  consideration,  1  volume  of  nitrogen  gas  combines  with 
exactly  1  volume  of  oxygen  gas  to  form  2  volumes  of  nitric  oxide  gas,  without 
condensation. 

g.  Hence,  if  the  specific  gravities  of  oxygen  and  nitrogen  gases  are  known,  that 
of  nitric  oxide  gas  may  be  cidcnlated  from  them.  And  since  it  is  known  that  if  a 
given  volume  of  atmospheric  air  weighs  1-0000  grain,  an  equal  volume  of  oxygen 
gas  will  weigh  1*1093  gr.,  and  an  equal  volume  of  nitrogen  gas  0*9706  gr.,  and  that 
2  vol.  nitrogen  gas  and  1  vol.  oxygen  gas  form  2  vol.  nitric  oxide  gas— -it  follows 
that  2  volumes  of  nitric  oxide  gas  must  weigh  as  much  as  1  vol.  nitrogen  gas  and 
1  vol.  oxygen  gas  together,  viz.,  0-9706  +  1'1093  =  2*0799. 


XV 


h.  liistly,  sinoe,  according  to  the  precediDg,  1  volume  of  nitric  oxide  gas  con- 
tains }  vol.  nitrogen  +  )  vol.  oxygen,  it  follows  that  by  adding  half  the  spedBc 
gravity  of  nitrogen  gas  to  half  the  specific  gravity  of  oxygen  gas,  we  shall  obtain 
the  specific  gravity  of  nitric  oxide  gas;  2:i±i*  _^    »•»<>»»  =  r0399. 


Chemical  Formula, — The  composition  of  bodies  is  explained  sometimes  by 
schemes,  sometimes  by  formulsB.  The  former  explain  themselves.  To  facilitate 
the  understanding  of  the  latter — ^for  which  purpose,  when  they  are  rather  long, 
mere  inspection  is  not  sufiicient — the  following  means  may  be  used: 

1.  Convert  the  formula  into  a  scheme,  (a)  by  placing  opposite  to  each  other,  in 
the  most  convenient  manner  possible,  the  substances  contained  in  the  first  part  of 
the  formula^  with  their  proper  numbers  of  atoms,  the  combined  substances  being 
connected  by  dotted  lines;  and  (6)  denoting  the  newly  formed  compounds  accord- 
ing to  the  second  side  of  the  formula,  by  f^  connecting  lines. 

As  an  example,  take  the  conversion  of  chlorate  of  potash  by  oil  of  vitriol  into 
bisulphate  and  perchlorate  of  potash  and  chloric  oxide  gas : 

3(KO,  CIO*)  +  4SO'  =  2(KO,  2SO»)  +  KO,  CIO'  +  2C10*. 

a.  b. 


KO   lO  I  OOOOCl 

JKO |0  I  OOOOCl 

KO    O   OOOOCl 


2S0'  KO  OOOOOCl     280' 

2SO^  KO  OOOOOCl      2SO» 

KO  OOOOOCl 

This  method  is  the  most  circumstantial,  but  at  the  same  time  the  clearest. 
2.  a.  Add  together  the  several  constituents  of  each  half  of  the  formula,  and 
9  whether  the  two  sums  are  equal : 

K     O    CI    S 

First  half:    3(K0,  CIO*)  3     18     3 

4SO*     12  4 


Second  half: 


3     30    3 
2(KO,2SO'>   2     14 


KOpClO' 
2C10* 


8     1 
8    2 


3    30    3     4 


b.  Or,  add  together  the  elements  of  the  first  half  of  the  formula,  and  from  the 
sum  thus  obtained,  deduct  the  elements  of  the  products  of  decomposition,  one  by 


3(K0,C10»)  +4SO> 
-2(KO,2SO^) 

K 

=  3 

2 

0  CI   s 
30    3     4 
14          4 

-K0,C10' 

=  1 

1 

16    3 
8     1 

=  2C10< 

8     2 

PART  II.  {continued.) 


SPECIAL   CHEMISTRY, 

OR 

THEOEY  OF  THE  AFFINITY  OF  INDIVIDUAL  SUBSTANCES. 


SECTION  II. 
Chemistry  of  Ponderable  Bodies. 

The  nnmber  of  undecomposed  ponderable  sabstances  at  present  known 
to  exist  is  61.  These  bo<lies  may  be  divided  into  Met^loids  or  Non- 
metallic  Elements,  and  Metals. 

12  Non-metallic  Elements :  Oxygen,  Fluorine,  Chlorine,  Bromine, 
Iodine,  Selenium,  Sulphur,  Phosphorus,  Boron,  Carbon,  Hydrogen,  and 
Nitrogen. 

49* Metals:  Potassium,  Sodium,  Lithium,  Barium,  Strontium,  Calcium, 
Magnesium,  Lanthanum,  Didymium,  Cerium,  Yttrium,  Erbium,  Terbium, 
Glucinum,  Aluminum,  Thorinum,  Zirconium,  Silicium,  Titanium,  Tan- 
talinm,  Niobium,  Pelopium,  Tungsten,  Molybdenum,  Vanadium,  Chro- 
mium, Uranium,  Manganese,  Arsenic,  Antimony,  Tellurium,  Bismuth, 
Zinc,  Cadmium,  Tin,  Lead,  Iron,  Cobalt,  Nickel,  Copper,  Mercury,  Silver, 
Gold,  Platinum,  Palladium,  Rhodium,  Iridium,  Ruthenium,  and  Osmium. 
No  exact  line  of  demarcation  can  be  drawn  between  metals  and 
metalloids  ;  silicium  is  sometimes  regarded  as  a  non-metallic  body ;  and 
iodine  and  bromine  as  metals. 

The  elementary  bodies  may  be  arranged  in  groups  according  to  their 
physical  and  chemical  relations  ;  and  these  groups  may  be  again  arranged 
according  to  their  more  general  resemblances.  The  following  is  an 
imperfect  attempt  of  this  kind.  The  only  way  of  making  a  satisfactory 
arrangement  would  be  to  dispose  the  elements,  not  on  a  plane  surface, 
but  within  an  envelope  of  three  dimensions. 


0                                             N 

H 

P  CI  Br  I 

L    Na     K 

S  SeTe 

Mg  Ca  Sr  Ba 

P   AsSb 

GErYTrCe  Di  La 

C  B  Si 

ZrThAl 

Ti  Ta  Nb  Pe  W 

SnCdZn 

Mo  V  Cr             U 

MnCo  NiPe 

Bi     Pb    Ag 

HgCu 

Ob  Rq    Ir      R 

Pt  Pd    Au 

*  Or  perhaps  51, — the  existence  of  two  other  metals,  Norium  and  Ilmeniam,  having 
lately  been  shown  to  be  probable.  This  would  make  the  total  namber  of  elements  63, 
instead  of  61.    [W.] 

VOL.  IT.  B 


2  INORGANIC  CHEMISTRY. 

Those  substances  which  stand  next  to  one  another  in  the  same  row, 
resemble  each  other  in  certain  respects.  Oxygen,  Hydrogen,  and  Ni- 
trogen stand  alone ;  there  is  no  known  element  analogous  to  either  of 
them.  The  groups  of  electro-negative  elements  are  placed  on  the  left ; 
those  of  the  electro-poeitiye  elements,  on  the  right. 

The  aboYe-named  elements  form  with  one  another  two  classes  of 
compounds — the  Organic  and  the  Inorganic,  All  the  elements  are 
capable  of  entering  into  inorganic  combinations ;  but  onl^  a  few  of  them — 
more  especially  Carbon,  Hydrogen,  Oxygen,  and  Nitrogen, — ^likewise 
form  organic  compounds.  Moreover,  inorganic  compounds  are  produced 
in  the  so-called  inanimate  world,  and  may  be  formed  artificially  from 
inorganic  materials.  Organic  compounds,  on  the  contrary,  originate 
almost  exclusively  in  plants  and  animals.  Art  may  indeed  convert  one 
organic  compound  into  another,  but  it  is  only  in  a  very  few  cases  that 
such  compounds  can  be  formed  artificially  from  inorganic  materials. 

Common  salt,  nitre,  glass,  brass,  &c.  are  inorganic  ;  sugar,  alcohols, 
fats,  resins,  glue,  &c.  are  organic  componnds.  A  more  exact  discrimination 
of  the  two  classes  will  be  given  in  the  Introduction  to  Organic  Chemistry. 


First  Division. 


Chemistry  of  Inorganic  Compounds^ 


OB 


INORGANIC  CHEMISTRY. 


Inorganic  Compounds  are : 

I.  Compounds  of  the  First  Order, 
f.«.  compounds  of  two  simple  substances:  and  these  may  be  arranged— 
(1.)  According  to  the  relative  numbers  of  their  atoms. 
A.  One  atom  of  the  one  substance  combines  with  one  atom  of  the 
other,  t,  g,  \\ 0,  CO,  H  CI,  KO,  NaS,  &c. 

"    '   *        ith  2  At.  c,  g.  H  0«,  C  0',  S0»,  PbO»,  KS«. 

ith  3  At.  e. g,  BO',  P0»,  S0^  CrO»,  POP,  NH«  SbG*. 
rith  4  A t.  tf.  ^.  N  0*,  CI  0*,  N  H*,  Os  0*. 
ith  5  At.  e,g.  PO»,C10*,SbO»,PCRSbCP. 
^ith7  At.€.y.  lO^ClO^ 
rith  3  At.  (?.  g.  Fe»  O*,  Cr*  0». 
'ith5  At.  tf.y.  S«0». 
ithr  At.  «.^.  Mn'O^ 
ith  4  At.  e,g.  Fe»0*,Mn»0*  Pb»0*. 
ith  5  At.  eg,  S»0*. 
T?^n»  ^^"^""^  complicated  relations  are  likewise  met  with,  e.g.  Pe»S», 
J?e"U .     It  IS  a  question,  however,  whether  every  inorganic  compound 


B.  1  At.  w 

C.  1  At.  w 

D.  1  At.  w 

E.  1  At.  w 

F.  1  At. 

G.  2  At.  wi 
H.  2  At.  w 
I.  2  At.  w 
K.  3  At.  w 
L.  3  At 


COMPOUNDS  OF  THE  FIRST  ORDER.  3 

which  eoniains  more  than  one  atom  of  each  of  its  elements  ought  not  to  be 
regarded  as  a  compound  of  the  second  order.  Thus,  S'O*  may  be  expressed 
hy  SO'  +  S0»;  S*0^  by  2S0  +  SO',  &c.,  &c.  In  the  case  of  Mn'O^,  such 
an  altei^tion  of  the  formuk  cannot  however  be  admitted,  so  long  fw  no 
higher  degree  of  oxidation  of  manganese  is  known  to  exist. 

(2.)  According  to  the  electro-negative  element. 
rniTi^"^^!  aiP^^^'"'''  —  ^''^'  "^'^^  Metalloids,  €.^.  HO,  H0»,  CO, 

(b)  With  Metals, e.  g.KO,K 0»,  Ti 0\  Cr»0',  Cr 0«,  As  0^  As  0»,  Pb 0. 

Compounds  of  Fluorine :  Flvarides.—(a.)  With  Metalloids,  e.  a.  HF. 
BF».— (6.)  With  Metals,  e.g.  CaF,  SiFV  >     !f         > 

^^S^S^?<>^^^o{Ch[oTine:Chlofides.—(a,)  With  Metalloids,  «.  ^.  HCl, 
POP,  PC1»,  S»C1  -(6.)  With  Metals,  e.  g.  Ac\,  Fe'CP,  6nCl< 

The  Compounds  of  Bromine  and  Iodine  (Bromides  and  Iodide$)  corre- 
spond to  those  of  Chlorine. 

Compounds  of  Selenium  ;  Selenides  or  SeUniureU.'^(a.)  With  Metal- 
loids, e.g.  PSe,SSe.— (6.)  With  Metals,  e.g.  KSe,PbSe. 

Compounds  of  Sulphur,  Sulphides  or  SulphureU,—(a.)  With  Metal- 
loi<b  e.g.  HS,HS»,CS*,PS — (6.)  With  Metals,  e.g.  KS,FeS,AsS», 
AsS'. 

Compounds  of  Phosphorus  and  Carbon  with  Metals;  Phosphides  or 
Phasphurets,  and  Carbides  or  Carburets. 

Compounds  of  Nitrogen,  with  Hydrogen,  e.g.  NH»,  and  with  Metals. 

Compounds  of  a  more  electro-negative  metal  with  a  more  electro- 
positive metel:  simple  alloys,  e.  g.  Arsenides,  TeUwides,  Antimonides,  &c. 

(3.)  According  to  the  electro-positive  element. 

^«f'??^'*°^*^^^^*^*™'«-^-^^»KO>,KF,KCl,KBr,KI,KSe,KS, 
KS»,  K8»,  K  S\  KS»,  K'P.     Simikrly  with  the  other  metals. 

Compounds  of  Hydrogen,  e.  i^.  HO,  HO^H«P,  HS,  HS^  HSe,  HI, 
HBr,  HC1,HF,  H>N,H»As,  HTe.  This  group  includes— amongst  other 
compounds-— all  the  inorganic  Hydrogen-acids. 

(4.)  According  to  the  physical  and  chemical  relations  of  the  com- 
pounds. 

^  Difficult  as  it  may  appear  to  arrange  all  compounds  of  the  first  order 
in  definite  groups,  according  to  this  principle  of  classification,  it  is  not  the 
less  obvious  that  the  greater  number  of  these  compounds  may,  with  more 
or  less  propriety,  be  divided  into  two  classes,  viz ,  those  of  Inorganic 
Acids,  and  Inorganic  Salijiahle  Bases.  The  characters  of  these  two  classes 
are,  m  many  of  the  compounds  belonging  to  them,  most  decidedly  marked; 
whereas,  in  many  others  they  are  so  much  modified  as  to  throw  consi- 
derable doubt  on  the  exact  chemical  nature  of  the  compounds  to  which 
they  belong. 

There  appears  also  to  be  a  gradual  transition  from  the  strongest  acids 
through  the  weaker  acids,  and  thence  through  the  weaker  bases  to  the 
strongest  bases, — so  that  the  idea  of  acid  and  base  becomes  merely  rela- 
tive. Alumina  must  be  regarded  as  a  base  when  in  combination  with 
sulphuric  acid;  but  in  combination  with  the  much  more  strongly  basic 
substance,  potassa,  it  acts  as  a  very  weak  acid.  Compounds  of  this 
medium  character,  such  as  alumina,  peroxide  of  tin,  water,  &c.,  are  some- 
times denominated  Amphoteric  compounds. 

Inorganic  Acids  are  more  electro-negative  than  salifiable  bases;  and 

B  2 


4  INORGANIC  CHEMISTRY. 

when  their  compounds  with  these  latter,  or  with  water,  are  subjected  to 
the  action  of  the  electric  current,  the  acids — when  not  themselves  decom- 
posed— are  evolved  at  the  positive  pole.  They  are  mostly  soluble  in 
water — have  a  sour  taste — many  of  them  exert  a  corrosive  action  on 
organic  substances — they  redden  the  blue  colour  of  litmus,  and  of  various 
flowers,  the  violet  for  example, — exhibit  great  affinity  towards  salifiable 
bases,  and  neutralize  them  more  or  less.  They  are  divided  into  Oxygen- 
adds,  such  SB  COSPO,PO»,PO*.SO,SO»,SO«,AsO»,AsO*,&c.— and 
Hydrogen-addty  such  as  HF,  HCl,  HBr,  &c.  Since  these  more  strongly 
marked  acids  all  contain  either  oxygen  or  hydrogen,  these  two  bodies 
may  be  regarded  as  the  Acidifying  Principles;  the  body  combined  with 
them  is  the  Radical  of  the  A  cid. 

Besides  these,  however,  many  compounds  of  Fluorine,  Chlorine,  Iodine, 
Selenium,  and  Sulphur  with  non-meUdlic  elements,  c.  ^.  BF',  BCl',  PCI*, 
PC1*,CS',  &c.,  and  with  the  more  electro-negative  metals,  e.g.  HgCl, 
PtCP,  AsS*,  AsS^  Sec,  may  be  regarded  as  acids  in  the  more  extended 
sense.— although  they  are  lor  the  most  part  destitute  of  the  above  men- 
tioned properties  of  acids,  with  the  exception  of  their  electro-negative 
character,  and  their  power  of  combining  with  certain  salifiable  bases. 

Inorganic  Salijiable  Bases  are  more  electro-positive  than  acids;  and, 
when  their  combinations  with  acids  are  subjected  to  the  electric  current, 
they  are  liberated  at  the  negative  pole.  A  few  of  them  only  are  soluble 
in  water;  and  in  this  case  they  are  characterized  by  a  taste  different  from 
that  of  acids,  aud  by  opposite  actions  on  vegetable  colours.  They  all 
exhibit  affinity  towards  acids,  and  neutralize  them  more  or  less. 

Almost  all  salifiable  bases  in  the  more  restricted  sense,  are  metallic 
oxides;  in  them  the  oxygen  must  be  regarded  as  the  Basic  Principle.  The 
same  metal  which,  with  a  small  quantity  of  oxygen,  forms  a  base,  e.g. 
MnOy  may,  when  combined  with  a  larger  quantity  of  oxygen,  produce  an 
acid^  e.g.  MnO*.  In  the  base,  the  electro-positive  nature  of  the  metal 
exerts  the  greater  power;  in  the  acid^  the  electro-negative  tendency  of  the 
oxygen  has  the  advantage. 

These  basic  metallic  oxides  may  be  divided  into  three  classes. 

Inorganic  Alkalis.  These  oxides  are  soluble  in  water, — corrode 
animal  substances, — ^have  a  soapy  or  urinous  taste — change  the  colour  of 
most  blue  or  red  flowers  to  green,  the  yellow  colour  of  turmeric  root  to 
red, — -and  restore  the  blue  colour  of  litmus  which  has  been  reddened  by 
an  acid.  Of  all  bases  they  have  the  strongest  affinity  for  acids,  and 
neutralize  them  most  completely.  To  this  class  belong  KO,NaO,  LO, 
BaOjSrO,  CaO,  and  likewise  ammonia,  NH*.  Since,  however,  this  last 
substance  in  its  compounds  is  always  associated  with  an  atom  of  water,  it 
may  likewise  be  regarded  as  NH*0.  If  ammonium,  NH*,  be  regarded 
as  a  compound  metal,  the  oxide  of  ammonium,  NH*0,  must  also  be 
looked  upon  as  a  metallic  oxide. 

Earths.  These  bodies  are  colourless,  have  a  specific  gravity  below 
4*000  or  5'000,  are  very  difficultly  fusible,  not  volatile,  insoluble  in  water, 
tasteless,  destitute  of  corrosive  action,  and  have  no  effect  on  vegetable 
colours ;  they  exhibit  less  affinity  for  acids  than  the  alkalis  do,  and 
neutralize  them  less  completely.  To  this  class  belong  MgO,  YO,GO, 
A  1*0',  &c. 

Salijiable  Heavy  Metallic  Oxides.  Many  of  these  compounds  are  co- 
loured, of  a  specific  gravity  higher  than  5  000,  easily  fusible  or  volatile  ; 
some  of  them  exhibit  a  certain  degree  of  solubility  m  water,  alkaline  re- 
_„  action,  and  metallic  taste.    Their  affinity  for  acids  is  in  some  cases  greater. 


COMPOUNDS  OF  THE  SECOND  ORDER.  5 

in  others  less,  than  that  of  the  earths.  This  class  includes  :  FeO,  CuO, 
Hg»0,  HgO,  Fe«0»,  &c. 

The  alkalis^  earths,  and  heavy  metallic  oxides  exhibit  many  gradations 
one  into  the  other,  and  no  exact  lines  of  demarcation  can  be  drawn 
between  them. 

In  this  class  also,  as  in  that  of  acids,  the  compounds  of  fluorine,  chlo- 
rine, bromine,  iodine,  selenium,  sulphur,  tellurium,  arsenic,  &c.,  with 
the  more  electro -positive  metals,  may  be  regarded  as  salifiable  bases  in 
the  more  extended  sense. 

II.  Compounds  of  the  Second  Order, 

I.  Combinations  of  a  Compound  of  the  First  Order  with  an 
Elementary  Body. 

To  this  division  belong:  C0,C1,— S0»,  C1,--S»0»,C1,— CrO^Cl,— 
MoO^Cl,&c. 

These  compounds  may  be  regarded  in  three  different  points  of  view  : 
(1.)  Phosgene,  for  example,  CO,  01,  consists  of  carbonic  oxide,  00,  and 
chlorine  ;  and,  in  fact,  it  is  produced  by  bringing  these  two  gases  together 
under  the  influence  of  light. — (2.)  Or  it  is  a  compound  of  carbonic  acid, 
CO',  with  a  bichloride  of  carbon,  CCl*,  not  yet  isolated;  according  to 
this  view,  phosgene  would  be  CO',  COP. — (3.)  Or  it  is  carbonic  acid,  CO', 
in  which  one  atom  of  oxygen  is  replaced  by  an  atom  of  chlorine, — there- 
fore C  0  01.  — According  to  the  first  and  second  of  these  views,  phosgene 
is  a  compound  of  the  second  order  ;  according  to  the  third  view,  it  is  of 
the  first  order. — Similarly,  SO',  CI  may  be  represented  as  2S0',SC1',  or 
as  SO'Cl ;— also  S' 0»,  C1=5S0',  SC1»=S»0»C1 ;— and  CrO',  Cl=2Cr 0', 
CrCl'=CrO»Cl,  &o. 

2.  Combinations  of  one  Compound  of  the  First  Order  with  another. 

Simple  Salts  in  the  vndest  sense. 

The  electro-negative  compound  contained  in  these  bodies  may  be 
regarded  as  the  acid, — and  the  electro-positive  compound  as  the  base  in 
the  more  extended  sense. 

A.  The  two  Compounds  of  the  First  Order  contain  a  Common  Element. 

(a)  Hydrates.  Compounds  of  water  with  oxygen  acids,  in  which  the 
water  plays  the  part  of  a  base  :  e.  g.  H  0,  SO^ — and  with  salifiable  bases, 
in  relation  to  which  it  must  be  regarded  aA  a  weak  acid  :  e.  g.  KO,HO. 
The  combination  generally  takes  place  according  to  equal  numbers 
of  atoms.  (Vid.  Hydrogen.)  These  hydrates  may  be  considered  as 
belonging  to  the  class  of  oxygen-salts. 

(b)  OxygensaUs.  Compounds  of  an  oxygen-acid  with  a  salifiable 
metallic  oxide. — From  the  combination  of  alkalis  with  acids  are  derived 
the  Alkali'saits,  (Alkali-oder  Neuiral-salze*);  the  earths  in  combination 
with  acids  yield  the  Medium  Salts  {Mittel-salze);  and  the  heavy  metallic 
oxides  yield  the  Heavy  Metallic  Salts,  or  simply  Metallic  Salts. 

The  Oxygen-salts  may  be  divided  : 

1.  According  to  their  Acid;  into  Carbonates,  StdpkateSy  Chlorates, 
Nitrates,  Arseniates  &c. 

*  This  term  can  scarcely  be  translated :  we  do  not  use  the  term  Neutral  Salt  in  the 
manner  here  indicated. 


6  INORGANIC  CHGMISTRT. 

2.  According  to  their  Base ;  into  salts  of  Ammonia,  FoUutd,  Mag- 
netia,  Protoxide  of  IroUy  Sftqui-oxide  of  Iron,  &c. 

8.  According  to  their  taste  and  their  action  on  regetable  colours.  If 
they  redden  litmus  and  have  a  sonr  taste,  they  may  be  designated  as 
Acid  Salts;  if  they  redden  turmeric,  and  have  an  alkaline  taste, — or  at 
aU  events,  if  they  contain  a  greater  quantity  of  base  than  is  necessary  to 
neutralize  the  specific  reaction  of  the  acid, — they  are  called  B<uie  Salts ; 
and  if  they  have  neither  an  acid  nor  an  allutline  reaction,  the  term 
Neutral  Salts  may  be  applied  to  them. 

This  mode  of  division,  first  introduced  by  Berthollet  (N.  Gehl,  3, 
248),  and  still  frequently  employed,  is  of  a  very  uncertain  character. 
Insoluble  salts  generally  appear  neutral,  merely  in  consequence  of  their 
insolubility,  whatever  may  be  the  proportion  of  base  and  acid  of  which 
they  are  formed.  Ainon^  the  soluble  salts,  on  the  contrary,  very  few  are 
perfectly  neutral  towards  delicate  reagents :  thus,  certain  sails  of  the 
alkalis, — ^sulphate  of  lime,  for  example, ~have  a  feeble  alkaline  reactios ; 
and  the  salts  of  the  earths  and  heavy  metallic  oxides, — if  they  only  con- 
tain a  sufficient  quantity  of  acid  to  render  them  soluble  in  water,  are  for 
the  most  part  slightly  acid. 

4.  According  to  the  number  of  atoms  in  which  the  acid  aad  baae  ax<e 
united :  Stoichiometrical  Classification, 

Either  the  acid  and  base  are  united  in  the  normal  proporiioii,*^ 
Normal  Salts*;  or  the  salt  contains  an  excess  of  acid, — Acid  Salts;  or 
an  excess  of  base, — Basic  Salts. 

Normal  Oxygen-salts.  These  salts  generally  coutain  one  aiom  of 
base  to  one  atom  of  acid  ;  but  there  are  certain  acids  which  require  more 
than  one  atom  of  base,  and  contain  bases  which  require  more  than  one 
atom  of  acid  to  form  normal  combinations.  Hence  acids  and  bases  may 
be  divided  into  the  following  groups. 

Monobasic  Oxygen-acids  ;  e.  g,  C  0',  Si  0\  Ti  0%  S  0*,  S  0',  CI  0*,  N  O* 
Metaphosphoric  acid = a  PO^  One  atom  of  each  of  these  acids  takes  up 
one  atom  of  a  mon-acid  base. 

Bibasic  Oxygen-acids.  The  only  acid  possessing  this  property  is  the 
Pyrophosphoric,  6P0^  One  atom  of  this  acid  combines  wiUi  two  atom* 
of  a  mon-acid  base. 

Tribasic  Oxygen-acids.  PO',  ordinary  Phosphoric  acid=cPO',  and 
A80^  One  atom  of  each  of  these  acids  combines  with  one  atom  of  a  mon- 
acid  base  ;  and  if  this  is  not  present,  one  or  two  atoms  of  water  are  taken 
l3p  in  place  of  one  or  two  atoms  of  the  deficient  base. 

Al'O',  Cr>0>,  Mn'O*  and  Fe'O*  seem  likewise  to  belong  to  this  gtovp. 

A  great  many  of  the  organic  acids  are  polybasic. 

Metaphosphoric  acid,  pyrophosphoric  acid,  and  ordinary  phosphorie 
acid  have  all  the  same  composition,  viz.  PO*:  they  are  isomeric  (vid. 
Vol  I.,  p.  109).  To  distinguish  between  the  formulse  of  these  acids^  the 
letters  a,  h,  c,  are  prefixed  to  them  ;  a,  the  first  letter  of  the  alp^bet, 
denotes  that  the  add  is  monobasic ;  h,  the  second,  that  it  is  bibasic  ;  >uid 
c,  the  third,  that  it  is  tribasic. 

Af  on-acid  Oxygen-bases.  To  this  group  belong  all  those  which  contain 
one  atom  of  oxygen  united  to  one  or  two  atoms  of  metal :  e.  ^.  K  O, 
MgO,  Hg^O,  HgO.     They  form  normal  salts  when  they  combine  with 

♦  Since  normal  salts  often  exhibit  acid  or  alkaline  reactions,  and  are,  oonseqaently, 
not  neutral  to  the  taate  or  to  vegetable  oolonrs,  I  have,  in  order  to  avoid  miaooaoeptlon, 
adopted  the  term  normaf  ii^stead  of  neutral  for  salts  composed  acooidinc  to  the  rccnlar 
preparation.  •  ^ 


COMPOUNDS  OF  THE  SECOND  ORDER.  ^ 

one  atom  of  a  monobaaio  acid;  e.  g.  KO,  CO', — NaO,  SO*, — Hg'O, 
N  0^ : — Of  a  bibasio  acid,  each  atom  requires  two  atoms  of  a  mon-acid 
base;  e.  g,  2NaO,6PO'j  and  of  a  tribasic  acid,  each  atom  requires 
three  atoms  of  a  mon-acid  base:  e,  g.  3NaO,  cPO*,— 3ZnO,  Fe*0^ — 
3MgO»,  APO». 

Biriieid  Bases.  These  contain  two  atoms  of  oxjgen  for  each  atom  of 
metal:  tf.  ^.  MoO",  VO*,  SnO':  in  their  normal  salts,  two  atoms  of  a 
monobasic  acid  are  united  with  one  atom  of  base  :   e.  g.  Y  0\  2S  0\ 

Ter-add  Bases,  In  these  bases,  three  atoms  of  oxygen  are  united  with 
one  or  two  atoms  of  metal :  e.  g.  APO^Cr^O',  U^O',  Fe'O',  Bi'O^,  SbO*, 
AsO^.  Their  normal  salts  contain  three  atoms  of  monobasic  acid 
united  with  one  atom  of  base :  e.  g.  BPO',  3N0*,— Pe'O^  3S0»,— SbO», 
3S0». 

The  1-^  2-,  or  3-acid  nature  of  a  base  is  therefore  dependent  on  the 
quantity  of  oxygen  which  it  contains.  Each  atom  of  oxygen  in  the 
base  requires  one  atom  of  a  monobasic  acid ;  and  the  ratio  between  the 
quantities  of  oxygen  in  the  acid  and  the  base  is  a  constant  quantity. 
Thus,  in  the  sulphates,  the  oxygen  of  the  sulphuric  acid  is  always  three 
times  as  much  as  that  in  the  Imlso  united  with  that  acid  to  form  a  nor- 
mal salt, — whether  the  base  be  1-,  2-,  or  3-acid.  Similarly  in  the 
normal  carbonates,  e.  g,  KO,  00^  the  quantity  of  oxygen  in  the  acid  is 
equal  to  that  in  the  base  multiplied  by  2 ;  in  the  nitrates,  e.  g,  K  0,  N  0^ 
by  5;  in  the  metaphospbates,  e.g,  NaO,  aPO',  by  5  ;  in  the  pyro- 
phosphates, e,  g.  2NaO,6PO^  by  fi  ^^^  ^  the  ordinary  phosphates, 
<.y.  3NaO,«PC)«,by4. 

The  expression,  CapacUg  qfScUuraiton  of  an  acid  is  used  by  Berzelius 
to  denote  tlie  quantity  of  oxygen  contained  in  that  quantity  of  base  by 
which  100  parts  of  the  acid  are  converted  into  a  normal  salt.  Thus,  the 
capacity  of  saturation  of  sulphuric  acid  is  20  ;  that  is  to  say,  100 
parts  of  that  acid  take  up  such  a  quantity  of  any  given  base  that  the 
quantity  of  oxygen  contained  in  it  amounts  to  20  parts.  This  num- 
ber is  found  by  dividing  the  quantity  of  oxygen  contained  in  100 
parts  of  the  acid  by  the  number  which  shows  how  many  times  the  quan- 
tity of  oxygen  in  the  base  is  contained  in  that  belonging  to  the  acid. 
Thus,  100  parts  of  sulphuric  acid  contain  sixty  parts  of  oxygen  ; — and  in 
the  sulphates,  the  acid  contains  three  times  as  much  oxygen  as  the  base  ; 
V=20, 

Normal  salts  are  neutral  to  the  taste  and  to  vegetable  colours  only 
when  they  are  insoluble,  or  when  the  acid  and  base  have  about  equal 
power.  When  the  base  is  powerful,  e.  g,  an  alkali,  and  the  acid  weak,  e,g, 
oaibonic  or  boracic  acid,  the  reaction  of  the  alkali  predominates  :  on  the 
other  hand,  when  the  acid  is  relatively  stronger,  the  normal  salt  exhibits 
an  acid  reaction:  e.g.  CuO,SO^— Fe»0%3S0\ 

Acid  Oxygenscdts*  These  are  formed  when  one  or  more  atoms  of  an 
acid  are  added  to  one  or  more  atoms  of  a  normal  salt;  e. y.  KO^ 
«S0%— KO, 2CrO»,— K0,3T0»,— KO,  4TiO».  K  the  acid  salts  contain 
water  intimately  combined,  they  may  likewise  be  regarded  as  double  salta 
in  which  the  water  plays  the  part  of  the  second  base  :  thus,  K0>  230* 
+  H0  may  likewise  be  written,  KO,SO'-|-HO,  S0». 

Basic  Oxygen-salts.  These  compounds  arise  from  the  combination  of 
one  or  more  atoms  of  the  normal  salt  with  one  or  more  atoms  of 
the  base:  e.  g,  2PbO,C^O^— 2PbO,NO*,— 3PbO,NO»,— 6PbO,NO^ 
These  also,  when  they  contain  water  intimately  combined^  may  be  rer 
garded  as  a  species  of  double  salt^  or  as  oompouncUi  of  the  normal  salt  with 


8  INORGANIC  CHEMISTRY. 

the  hydrate  of  the  base,  the  water  in  the  hydrate  playing  the  part  of  an  acid. 
Thus,  malachite  is  2CuO,CO--|-nO=CuO,CO',-|-CuO,  HO. 

Many  acid  salts  exhibit  acid  re-action  ;  many,  however,  are  neutral 
or  even  have  an  alkaline  reaction,  if  the  base  be  strong  and  the  acid  very 
weak,  as  in  the  case  of  KO,  2C0^and  NaO,2B(P.  Most  basic  salts 
are  insoluble,  and  therefore  exhibit  no  particular  reaction. 

In  designating  salts  according  to  their  stoichiometrical  composition,  the 
names  may  be  formed  either  according  to  the  number  of  atoms  of  acid  united 
with  one  atom  of  base,  or  according  to  the  number  of  atoms  of  base  united 
with  one  atom  of  acid  ;  hence  we  have  the  following  nomenclature  : — 

1  atom  of  acid  to  1  atom  of  base  : — Simple  or  Man^ctcid  ScdtSf  e.  g, 
simple  sulphate  of  potassa  =  KO,  SO',  simple  carbonate  of  soda  =  NaO, 
CO^  simple  sulphate  of  alumina  =  AP  0^,80',  simple  phosphate  of 
soda  =  NaO,  PO*. 

2  atoms  of  acid  to  1  atom  of  base  :  Bi-cteid  SaltSy  e,  g,  bichromate  of 
potassa  =  K0»,  2CrO». 

3  atoms  of  acid  to  I  atom  of  base  :  Ter-acid  Salts,  e.  g.  teriodate  of 
potassa  =  KO,  31 0«,  tersulphate  of  alumina  =  Al*0«,  3S0». 

4  atoms  of  acid  to  1  atom  of  base  :  Quadrdcid  Salts :  e,  g.  quadro- 
titanate  of  potassa  =  KO,  4TiO'. 

3  atoms  of  acid  to  2  atoms  of  base  :  Sesqui-acid  Salts,  e,  g,  sesqui- 
carbonate  of  soda  =  2 NaO,  3C0',  which,  however,  since  it  cannot  be 
obtained  anhydrous,  may  be  regarded  as  a  double  salt,  viz.,  2NaO, 
2C0»^H0,C0». 

1  atom  of  acid  to  2  atoms  of  base  (=  ^  :  1)  :  JDi-acid  or  Bibasie 
Salts,  e.  g.  dichromate  of  oxide  of  lead  =  2PbO,  CrO',  disulphate  of 
sesqui-oxide  of  iron  =  2Fe*0',S0^  diphosphate  of  soda  (ordinary  phos- 
phate of  soda)  =  2NaO,  cPO*  (neglecting  the  atom  of  basic  water 
contained  in  it). 

1  atom  of  acid  to  3  atoms  of  base  (=  ^  :  1) :  Trit-acid  or  Terhasic 
Salts,  e.  g.  trinitrate  of  oxide  of  lead  =  3PbO,NO»,  trisulphate  of 
protoxide  of  mercury  =  3HgO,  SO',  triphosphate  of  soda  =  3NaO, 
cPO». 

1  atom  of  acid  to  6  atoms  of  bajse  (=  4-  :  1)  .-  l-acid  or  Sexhasic 
Salts,  e,g.  6PbO,  NO*. 

2  atoms  of  acid  to  3  atoms  of  base  (=  4  •  1)  ^  ^acid  or  Sesquibasic 
Salts,  <?.  g.  3Hg«0, 2N0»,  3AP0',  2  c  PO*  (Wavellit^). 

A  few  other  proportions  of  the  number  of  atoms  of  acid  and  base  are 
likewise  occasionally  met  with. 

Generally  speaking,  simple  salts  are  likewise  normal :  such,  in  fact, 
is  always  the  case  when  a  mon-acid  base  is  associated  with  a  monobasic 
acid,  €,  g.  KO,  NO',  or  a  ter-acid  base  with  a  terbasic  acid,  «.  g.  APO', 
c  PO*.  But  when  a  mon-acid  base  is  combined  atom  for  atom  with  a 
bibasioor  terbasic  acid,  e.g.  NaO, cPO*,  an  acid  salt  is  produced,  be- 
cause the  acid  requires  two  or  three  times  that  Quantity  of  base ;  and  one 
atom  of  a  monobasic  acid  with  1  atom  of  a  bi-acia  or  ter-acid  base  produces 
a  basic  salt,  because  the  single  atom  of  that  base  requires  2  or  3  atoms  of 
acid  in  order  to  produce  a  normal  salt. 

(c)  Fluorine-saUs,  Combinations  of  one  fluorine-compound  with 
another. 

The  following  are  compounds  of  this  kind  :  KF,  HF, — KF,  BF'  — 
K F,  Si F»,— K  F,  Ti  P,~K F,  2ZrF,— 3NaF,  AP F». 

The  fluorine  in  these  compounds  takes  the  place  of  the  oxygen  in 
oxygen-salts  :  if,  therefore,  the  fluorine  contained  in  them  be  replaced  by 


COMPOUNDS  OF  THB  SECOND  ORDER.  9 

the  fluorine-salts  are  converted 
,BF'  becomes  KO,BO',  and  so 
regard  to  the  following  salts ;  their  com- 
position is  analogous  to  that  of  oxygen-salts,  the  place  of  the  oxyi|;en 
being  supplied  by  fluorine^  chlorine,  bromine,  iodine,  selenium,  or  sulphur. 

(d)  CfhloHne-salts.  Combinations  of  one  chlorine  compound  with 
another. 

To  this  group  belong:  SnC1^2SCl^— SbCl',  3SCP,—KC1,  HffCl, 
— KCl,2HgCl, — KCl,4HgCl  (bi-acid  and  quadracid  chlorine-salt^,— 
K  CI,  Sn  CP,— K  CI,  Pt Cl«,— K  CI,  Au  Cl». 

(e)  Bromine^saUs,  Combinations  of  one  bromine  compound  with 
another. 

KBr,  PtBr^— KBr,  AuBr». 

(f)  Iodine-sails,  Combinations  of  one  iodine  compound  with 
another. 

KI,  AgI,--KT,2AgI(a  bi-acid  iodine-salt),— KI,PtP,— KI,  AuP. 

(g)  Selenium-salts.  Combinations  of  two  simple  selenium-compounds. 
Selenide  of  copper  and  lead  =  2PbSe,CuSe. 

(Ij)  Sulphur-scUts.     Combinations  of  two  simple  sulphur  compounds. 

The  electro-negative  compound  contained  in  a  sulphur-salt  is  called 
the  Sulphur-acid;  the  electro-positive  compound,  the  sulphur-base. 
Both  art  and  nature  furnish  numerous  compounds  of  this  class;  e.  g. 
KS,  HS,— KS,  CS»,— KS,  HgS,— Grev  copper  =  Fe»S',  Cu»S,— Purple 
conper  =  Fe»S',  SCu'S,— Brittle  sulphide  of  silver  =  6AgS,  SbS^— Dark 
red  silver  =  3AgS,SbS', — Miargyrite  =  AgS,SbS',  —  Boulangerite  = 
3PbS,  SbS^— Antimonial  Featherore  =  2PbS,  SbS',— Zinkenite  =  PbS, 
SbS', — Schlippe's  salt  =  3NaS,SbS^  and  the  corresponding  arsenical 
compound,  3NaS,  AsS*. 

In  the  compounds  hitherto  enumerated — to  which  perhaps  the  arsenic- 
salts  and  tellurium-salts  ought  to  be  added,  the  electro-negative  consti- 
tuent of  the  two  simple  compounds  is  the  one  which  is  common  to  both.  In 
other,  less  frequent  combinations  of  the  second  order,  the  two  simple 
compounds  contain  a  common  electro-positive  element,  and  that  element 
is  a  metal.  To  this  class  belong,  particularly,  the  combinations  of  a 
metallic  oxide  with  the  chlorine,  bromine,  iodine,  or  sulphur  compound  of 
the  same  metal : 

Oxychiorides :  3Pb  0,  Pb  CP,— 5Sb  0^  Sb  CP. 

Oxybromides :  sm  Sb  O',  Sb  Br',— Oxiodides,  Sb  0»,  Sb  l\ 

Oxymlphides:  SbO',2SbS',— MnO,  MnS,— ZnO,ZnS. 

With  these  may  likewise  be  classed  the  following  compounds  :  SbS^ 
SbP, — White  precipitate  =  HgNH',  Hg CI, — Nickeliferous  grey  anti- 
mony =  NiSb,  NiS; — Arsenical  pyrites  =  FeAs,  FeS', — Co&,lt-glance 
=  CoAs,CoS»,  &c.  &c. 

Lastly,  we  may  admit  the  existence  of  Hydrogen-salts,  a  class  which 
will  include  all  compounds  of  ammonia  with  hydrogen-acids :  e,  g. 
Sal-ammoniac  =  H'N,  H CI ;  similarly,  H»N,  H  S,— H'N,  H I,— H» N, 
H  Br,  &c.  If,  on  the  other  hand,  we  suppose  that  the  hydrogen-acid 
gives  up  its  atom  of  hydrogen  to  the  ammonia,  thereby  converting 
that  compound  into  the  quasi-metal,  Ammonium  (N  H^),  the  formula  of 
sal-ammoniac  will  become  NH*C1;  it  will  no  longer  be  hydrochlorate 
of  ammonia,  but  chloride  of  ammonium,  and  must,  to  a  certain  extent,  be 
regarded  as  a  compound  of  the  first  order.  In  a  similar  manner, 
hydriodate  of  phosphuretted  hydrogen  may  be  regarded  either  as  H'P, 
HI,  or  as  PH*,  I. 


10  INORGANIC  CHEMISTRY. 


B.  The  two  Compounds  ofiheFir9t  Order^  whioh  uniU  to  forma  Compound 
of  the  Second  Order,  have  no  Common  Conetiiuent, 

Thb  case  ib  by  far  the  less  common  of  the  two. 

Many  anhydrous  ammonia-compoands  belong  to  this  diyision : 

NH',  CO»,-NH», SO*,— NH»,SO»,— 2N H',  COCl,— 5N H',  POP,— 
NH»,SC1,— NH»,  BP,— NH»,  SiF^,— N  H*,SiCP,NH',AsP,— andmany 
other  combinations  of  ammonia  with  metallic  ciklorides,  bromides,  and 
iodides. 

Likewise:  KCl,  2CrO';  in  this  case,  KO  is  replaced  hy  KCl. 

Lastly,  in  this  category  must  be  enumerated  the  Compounds  of 
Hydrogenrodde  tffith  Metallic  Oxides,  so  far  at  least  as  their  existence  is 
admitted.  Does  a  metallic  fluoride,  chloride,  bromide,  iodide,  selenide, 
sulphide,  or  telloride,  dissolve  in  water  as  such  %  or  does  it,  by  taking  up 
the  elements  of  water,  become  converted  into  a  soluble  hydrogen-siSt  of 
a  metallic  oxide?  or,  what  comes  to  the  same  thing — does  the  bringing 
together  of  a  hydrated  hydrogen-acid  and  a  metallic  oxide  immediately 
produce  water  and  a  compound  of  the  metal  with  the  radical  of  the 
hydroa^o-acid  %  or  do  the  metallic  oxide  and  the  hydrogen-acid  combine 
together  without  mutual  decomposition  ?  In  some  cases,  the  former  of 
these  modes  of  action  undoubtedly  takes  place  :  hydrated  hydrochloric 
acid  and  oxide  of  silver  immediately  produce  insoluble  chloriae  of  silver 
(AgO  -t-  HCl  =  AffCl  +  HO), which,  when  dried  at  a  gentle  heat, 
is  found  to  bo  free  from  oxygen  and  hydrogen.  On  the  other  hand,  if 
aqueous  hydrochloric  acid  be  neutralized  with  soda,  the  whole  remains 
dissolved,  forming  a  liquid  identical  with  that  which  is  obtained  by 
dissolving  common  salt  (NaCl)  in  water.  Whether  this  liquid  contains 
in  solution  NaCl,  or  NaO,  HCl,  is  a  question,  which  we  have  no  meana 
of  deciding.  If  the  solution  be  evaporated  and  exposed  to  a  temperature 
of —  10^,  it  yields  oblique  rhombic  prisms  of  a  hydrated  salt,  which 
may  be  regarded  either  as  NaCl  -h  4H0  or  as  NaO,  HCl  -H  3H0: 
according  to  the  former  view,  it  would  be  chloride  of  sodium  with  four 
equivalents  of  water  ;  according  to  the  latter,  hydrochlorate  of  soda  with 
three  equivalents  of  water.  If,  on  the  contrary,  the  saline  solution  be 
evaporated  at  the  ordinary,  or  at  a  higher  temperature,  it  yields  cubical 
crystals  of  common  salt,  NaCl,  which  are  ouite  free  from  water,  unless, 
perchance,  they  C(xitain  portions  of  the  mother-liquor  (water  of  decrepi- 
tation) enclosed  within  them.  According  to  the  former  view,  the  NaCl 
merely  separates  as  such  from  the  solution,  as  the  water  evaporates : 
according  to  the  latter  view,  the  0  of  the  NaO  combines  — as  the  water 
in  the  solution  diminishes  in  quantity — with  the  H  of  the  HCl,  forming 
water,  which  likewise  evaporates,  while  the  NaCl  crystallizes  out 

There  is  no  fact  yet  ascertained  by  which  either  of  these  theories  can 
be  positively  demonstrated  and  the  other  disproved.  Nothing  more  ^^b^n 
probable  arguments  can  be  alleged  in  favour  of  one  or  the  other. 

Arguments  in  favour  of  the  first  view — ^that  there  are  no  such  things 
as  hydrogen-salts  of  metallic  oxides; 

1.  The  union  of  two  compounds  of  the  first  order  not  containing  a  com- 
mon element  is,  as  far  as  other  cases  are  concerned,  of  very  rare  ocourrenoa. 

2.  It  is  more  simple  to  conceive  the  existence  of  NaCl,  &c.  as  such, 
in  the  state  of  aqueous  solution,  than  to  suppose  that  every  snch  case  of 
solution  is  accompanied  by  a  decomposition,  and  eyery  corresponding  case 


COMPOUNDS  OP  THE  SECOND  ORDER.  11 

of  ciystaUization  by  a  recomposition  of  water.  Tbis  advantage  in  point  of 
simplicity  is  particularly  evident  in  the  case  of  the  sulphur-salts.  For 
example :  according  to  the  first  view,  3NaS,  AsS*  dissolves  in  water 
without  change  of  composition  ;  according  to  the  second,  we  must  assume 
that  the  3Na  take  30  from  the  water,  and  that  the  As  takes  50 — so  that 
soda  and  arsenic  acid  are  produced ;  further,  that  the  8  atoms  of  hydrogen 
thus  set  free  from  the  water,  attach  themselves  to  the  (8  +  5)  S,  producing 
hydrosulphuric  acid;  and  thus,  3NaS,  AsS'  +  8H0  is  converted  into 
3(NaO,SH)  +  As0^5HS.  In  this  manner  a  double  hydrosulphato 
would  be  produced  :  its  composition  is,  however,  liable  to  the  objection 
that  the  stronger  acid  As  0',  nas  to  play  the  part  of  abase,  and  the  weaker, 
HS,  the  part  of  an  acid. 

3.  Many  sulphur-salts  contain  metallic  sulphides,  the  oxides  corre- 
sponding to  which  are  not  known  to  exist :  e.  ^.  KS,  MoS*  must,  accord- 
ing to  the  second  view,  be  converted  by  solution  in  water  into 
KO,HS  +  MoO*,4HSi  but  Mo 0*  is  a  degree  of  oxidation  of  molyb- 
denum not  otherwise  known. 

Arguments  in  favour  of  the  second  view,  according  to  which  the  com- 
binations of  metallic  chlorides,  &o«,  with  water,  contain  hydrogen-salts  of 
metallic  oxides. 

1.  Water  is  in  all  other  cases  most  inclined  to  dissolve  those  com- 
pounds which  contain  one  of  its  constituents :  thus  it  dissolves  acids, 
alkalis,  oxygen-salts,  &c.  Hence  it  is  probable  that  water  would  not 
dissolve  metallic  sulphides,  &c.,  if  these  compounds  did  not  previously 
take  up  the  elements  of  water. 

2.  No  simple  metal  is  soluble  in  water  :  tbence  it  appears  remarkable, 
according  to  tne  first  view,  that  telluride  of  potassium,  an  alloy  of  two 
metals,  should  dissolve  in  water ;  but  the  act  of  solution  becomes  easily 
intelligible,  if  we  suppose  the  potassium  previously  eonverted  into  K  0, 
and  the  tellurium  into  HTe. 

3.  Phosphide  of  potassium  in  contact  with  water  ffives  rise  to  phoa- 
phuretted  hydrogen  gas,  which  escapes,  and  oxide  of  potassium,  which 
remains  dissolved  in  the  water :  why  should  not  sulphide  of  potassium,^ 
in  contact  with  water,  produce  KO  and  H  S^  ?  The  cases  appear  precisely 
analogous ;  in  both  of  them,  the  great  affinity  of  potassium  for  oxygen, 
and  of  phosphorus  or  sulphur  for  hydrogen,  must  fi^ive  rise  to  decomposi- 
tion of  the  water  ;  the  only  difference  being  that  the  hydrosulphuric  acid 
produced  in  the  latter  case  remains  in  combination  with  the  potassa, 
whereas  the  phosphuretted  hydrogen,  for  which  potassa  has  no  afifnity,  i& 
evolved  in  the  form  of  eas. 

4.  Oxygen  is  considered  to  be  more  electro-negative  than  chlorine; 
nevertheless,  KO  dissolved  in  water  has  a  strong  alkaline  reaction, 
whereas  KCl  is  neutral.  This  apparent  anomaly  disappears  if  we  sup- 
pose KO  and  H 01  to  be  formed,  the  latter  of  which  eomponndei,  being  a 
strong  acid,  completely  nentralizes  the  potassa.  KS  dissolved  in  water 
exerts  an  alkaline  reaction,  because  HS  is  a  much  weaker  acid  than  HCl. 
And  generally,  the  reaction  of  KCl,  KI,  KS,  &c.,  in  the  state  of  aqueous 
solution,  stands  in  direct  relation  to  the  strength  of  the  hydrogen  acid  pro- 
duced in  the  act  of  solution. 

5.  Chloride  of  bismuth,  in  contact  with  water,  is  resolved  into  precipi- 
tated oxide  of  bismuth,  retaining  a  small  quantity  of  chloride,  and  hydrated 
hydrochlc«ic  aoid,  in  which  a  small  qnaAtity  of  oxide  of  bismuth  remains 
dissolved.     Here  it  is  plainly  seen  that  metallic  chlorides  in  contact  with 


12  INORGANIC  CUBMISTRT. 

water  produce  hydrogen  nlte  of  metallic  oxides,  which,  according  to  the 
nature  of  the  metal,  either  remain  dissolved  in  the  water,  or  are  resolved 
into  a  hasic  and  an  acid  salt — just  like  the  corresponding  nitrates. 

6.  When  a  solution  of  magnesia  or  alumina  in  dilute  hydrochloric  is 
evi4x>rated  to  complete  dryness,  there  remains,  not  MgCl  or  Al'CP,  hut 
MgO  or  AFO',  while  the  hydrochloric  acid  evaporates  with  the  water. 
This  fact  is  easily  explained  upon  the  second  hypothesis.  The  hydrochloric 
acid  having  but  a  feeble  affinity  for  these  earths  escapes,  the  separation 
being  induced  partly  by  its  attraction  for  heat,  partly  by  its  attraction 
for  water.  But,  according  to  the  first  hypothesis,  it  must  be  assumed  that, 
at  a  certain  degree  of  concentration,  the  MgCl  or  Al*Cl'  interchanges 
elements  with  the  water  still  remaining,  the  products  being  MgO  or  Al'O' 
which  remains,  and  HCl,  which  escapes. 

7.  The  aqueous  solution  of  protochloride,  protiodide,  &c.,  of  iron  ex- 
hibits the  same  reactions  as  the  compounds  of  the  protoxide  of  iron  with 
oxygen-acids  :  when,  therefore,  we  speak  of  the  reactions  of  the  salts  of 
protoxide  of  iron,  we  must  understand  by  this  expression,  not  only  the 
compounds  of  protoxide  of  iron  with  oxygen-acids,  but  likewise  the 
aqueous  solutions  of  protochloride  of  iron,  &c.,  although  the  latter, 
according  to  the  first  hypothesis,  do  not  contain  protoxide  of  iron.  Here, 
then,  we  either  introduce  an  ambiguity  by  tacitly  supposing,  as  is  com- 
monly done«  that  the  expression  "salt  of  protoxide  of  iron,"  likewise  ex- 
tends to  solutions  of  the  protochloride,  &c.,  or  else  we  must  in  every  case 
explicitly  declare  that  we  are  speaking  not  only  of  salts  of  the  protoxide 
of  iron,  but  likewise  of  the  aqueous  solutions  of  the  compounds  of  iron 
with  one  atom  of  fluorine,  chlorine,  bromine,  iodine,  &c.  Similarly  with 
regard  to  the  other  metals*. 

8.  The  aqueous  solution  of  nitrate  of  cobalt  is  red,  so  is  that  of  the 
chloride ;  but  the  former  solution  when  evaporated  to  dr3me8s  leaves  a 
red  residue,  the  latter,  a  blue  one, — because  the  oxygen-salt,  after  parting 
with  its  water,  still  remains  a  salt ;  whereas  dissolved  hydrochlorate  of 
the  oxide  of  cobalt  is  converted  on  evaporation  into  a  non-saline  body, 
the  chloride  of  cobalt.     Similarly,  with  chloride  of  chromium. 

The  most  probable  view  of  the  matter  appears  to  be  that  when  a 
metallic  chloride,  &c.  is  brought  in  contact  with  water,  the  opposing 
affinities  are  either  exactly  or  nearly  in  equilibrium.  In  the  case  of 
NaCl,  for  example,  the  afiinity  of  Na  for  CI  -f-  that  of  0  for  H  must  be 
considered  as  about  equal  to  the  affinity  of  Na  for  0  +  that  of  CI  for  H  + 
that  of  NaO  for  HCl.  If  the  former  sum  were  the  greater,  the  NaCl 
would  dissolve  as  such  in  the  water  ;  if,  on  the  contrary,  the  latter  sum 
were  the  greater,  the  compound  actually  dissolved  would  be  NaO,  HCl. 
Since,  however,  the  two  sums  appear  to  equilibrate  each  other,  we  may 
be  allowed  to  regard  a  metallic  chloride,  &c.  dissolved  in  water  in  the 

*  In  translating  this  paragraph^  it  was  necessary  to  adhere  stricdy  to  the  forms  of 
expression  adopted  by  the  author ;  otherwise  the  meaning  would  have  been  lost.  It 
must,  however,  be  observed  that  the  ambiguity  spoken  of  arises  from  the  use  of  the 
particular  expression  "salU  qf  protoxide  of  iron"  {Eitenoxydul-Mize) -,  but  if  we  adopt 
the  mode  of  expression  more  usual  in  EngUsh,  viz.,  **proto$alts  qfiron,**  the  ambiguity 
is  done  away  with ;  for  this  expression  is  at  once  understood  to  apply  to  the  protochloride, 
protiodide,  &c.,  as  well  to  salts  of  the  protoxide  properly  so  called.  Neither  is  there 
any  confusion  (notwithstanding  the  slight  dissimilarity)  in  explaining  the  action  of  dif- 
ferent reagents  on  the  sereral  solutions.  For  instance.  In  the  action  of  potassa  on  a 
solution  of  the  protsulphate  we  have :  FeO,  SO=*  and  KO  yield  FeO  and  KO,  80* ; 
and  in  the  case  of  the  protochloride^  PeCl  and  KO  yield  FeO  and  KCl.     [W.] 


COMPOUNDS  OP  THE  THIRD  OUDER.  13 

one  wa^  or  the  other,  according  to  the  greater  facility  of  explanation 
which  either  hypothesis  may  present.  For  example,  in  considering  the 
precipitation  of  CaCl  dissolved  in  water  by  KO,  CO',  it  is  easier  to 
adopt  the  second  hypothesis  and  explain  the  reaction  as  a  decomposition 
by  double  aflSnity,  whereby  CaO,HCl  and  KO,CO'  are  converted  into 
CaO,  CO®,  and  K0,HC1 — than  to  suppose,  according  to  the  first  hypo- 
thesis, that  CaCl  and  KO  yield,  also  by  double  affinity,  the  new  com- 
pounds CaO  and  KCl,  and  then  that  the  CO'  previously  combined  with 
the  KO  is  transfsrred  to  the  CaO.  But  in  many  other  cases,  e.  g.  in  that 
of  the  sulphur-salts  and  the  theory  of  the  preparation  of  kermes-mineral, 
the  first  mentioned  hypothesis  ^ives  by  far  the  simpler  explanations. 

The  former  theory  is  that  of  Berzelius,  who  first  reduced  it  to  a  com- 
plete form,  and  by  the  discovery  of  the  sulphur-salts  gave  it  important 
support.  Among  the  advocates  of  the  latter  theory  are :  R.  Phillips 
{Ann,  FhU,  17,  27) ;  Schnaubert  {J,  'pr.  Chem.  6,  353.) 

III.  Compounds  of  the  Third  Order, 

1,  Combinations  of  a  Compound  of  the  Second  Order  with  a 

Compound  of  the  First 

A.  Combinations  of  simple  Oxygen,  Fluorine,  Chlorine,  Bromine, 
Sodine,  Selenium,  and  Sulphur-salts  with  water :  e,  a.  Gypsum,  CaO, 
SO*+HO.   [^Vid.  Water,  in  the  chapter  on  Hydrogen.] 

B.  Combinations  of  simple  Oxygen-salts  with  Ammonia :  e,  g.  AgO, 
N0*-t-3NH'.     [Vid.  Ammoma,  in  the  chapter  on  Nitrogen^ 

C.  Certain  other  cases  belonging  to  this  head  :  Matlockite,  PbO, 
C0»  +  PbCl,— Pyromorphite,  3  (3PbO,  PO*)  -f  PbCl,— 3  (KCl,  HgCl)  + 
Cua,— HgNH»,  HgCl+2  HgO. 

2.  Combinations  of  two  Compounds  of  the  Second  Order  one 

with  the  other. 

Double  Salts  in  t/ie  most  extended  sense. 

A.  The  two  simple  salts  which  combine  together  contain  the  same 
acid.  This  cajse  is  the  most  frequent,  and  yiel<£  the  ordinary  Double  or 
Triple  salts.  It  appears  that  only  normal  salts  (pp.  6.... 8)  are  capable 
of  forming  double  salts. 

Double  Oxygen-salts :  K  0,  S  0'  -f  Zn  0,  S  0^,  —anhydrous  Alum  = 
K0,S0*-t-Al»0»,3S0\ 

In  this  class  may  likewise  be  included  those  compounds  in  which 
water  plays  the  part  of  one  of  the  bases,  «.  ^r  .K  0,  S  0*  -f  H  0,  S  01  Since, 
however,  KO, SO*  when  mixed  with  HO, SO'  gives  rise  to  considerable 
evolution  of  heat,  which  is  due  to  the  combination  of  KO,  SO'  with  S0=*, 
Hess  (Pogg.  52,  110)  gives  preference  to  the  formula,  KO,  2S0'  -f-  HO, 
according  to  case  iii,  i.  A. 

Polybasic  acids  may  combine  with  several  bases  at  once  without 
producing  a  double  salt  properly  so  called.  Thus,  an  atom  of  ordinary 
phosphoric  acid  requires  three  atoms  of  base  (metallic  oxide  or  water) 
to  saturate  it,  and  these  three  atoms  of  base  may  be  of  one,  two,  or 
three  different  kinds;  e,  g,  3NaO,cPO*,— (2NaO,  H0)+  cPO*-"(KO, 
NaO,HO)+(rPO». 

The  two  bases  of  a  real  double  salt  are  never  isomorphous,  (thus  in 
the  examples  above  given,  KO  is  not  isomorphous  either  with  ZnO  or 


14  INORGANIC  CHSMISTRT. 

with  APO*)  ;  but  phosphoric  acid  may  simultaneoualj  take  up  seyeral 
isomorphoufi  bases,  as  KO  and  NaO.  In  real  double  salts,  each  atom 
of  base  has  its  own  atom  of  acid  or  sereral ;  so  that  the  formula  divides 
itself  into  two  parts,  each  of  which  is  the  expression  of  a  simple  salt : 
but  in  those  salts  of  phosphoric  acid  which  contain  several  bases  to* 
gether,  such  a  diyision  cannot  be  made,  because  the  different  bases  belong 
altogether  to  the  same  atom  of  acid.  (Graham,  FkU.  Mag.  J.  18,  319  ; 
also  J.  pr.  Chem.  15,  437.) 

DoubU  Svlphur-9aUs,    Bonmonite  :   f3CuS,SbS»)  +  2  (3PbS,SbS»0 
Undoubtedlj  there   also   exists  double  fluorine,  chlorine,   bromine, 
iodine,  selenium,  and  tellurium-salts. 

B.  The  two  simple  baits  contain  the  same  acid.  This  case  is  of  rarer 
occurrence.  Copper  salammoniac ;  NH*,CuO  +  NH*0,SO*. — Similarlr, 
PbO,CO*-f.PbO,SO». 

IV.  Compounds  ofOu  Fourth  Order. 

To  this  class  belong  especiallj  the  compounds  of  double  salts  with 
water,  e.  g.  Crystallized  alum  :  (K  0,  SO*  -h  A1*,0',  3S0*)  +  24HO. 

V.  OompoundM  of  the  Fifth  Order. 

Under  this  head  maj  perhaps  be  included  the  solutions  of  crystallized 
alum  and  other  compounas  of  the  fourth  order  in  water  and  other  liq^uids  : 
definite  compounds  of  this  order  do  not  however  appear  to  exist 


Bemarhi  upon  the  Theory  of  Sake. 

The  idea  of  a  ecdt  has,  with  the  progress  of  chemistry,  nndergone  nume- 
rous alterations. 

1.  In  former  times,  the  term  eaU  was  applied  to  rarions  bodies  whose 
principal  characteristics  were  solubility  in  water,  a  peculiar  taste,  and 
generally  also  the  capability  of  crystallizing  :  and  these  bodies  were 
divided  into  Add  ealts  (the  oxygen  and  hydrogen-acids  of  the  present 
day)  ;  Alkaline  salts  (the  substances  now  called  alkalis)  ;  Neutral  salts 
(those  compounds  of  acids  and  alkalis  which  are  soluble  in  water) ;  Medium 
salts  (compounds  of  the  earths  with  a^ids) ;  and  Metallic  salts  (compounds 
of  the  heavy  metallic  oxides  with  acids).  Insoluble  compounds  of  alkalis, 
earths,  and  heavy  metallic  oxides  with  acids,  such  as  calcspar  and  sulphate 
of  lead,  were  classed,  not  with  salts,  but  with  the  earths  and  metallic 
calxes  :  on  the  other  hand,  sugar  was  called  a  vegetable  salt. 

2.  Since  the  introduction  of  the  antiphlogistic  theory,  all  compounds 
of  salifiable  bases  with  acids  have  been  reckoned  as  salts, — ^the  term  boie^ 
was  however  originally  restricted  to  the  salifiable  metallic  oxides  and 
ammonia,  and  the  term  acid  to  those  which  are  now  denominated 
oxygen  and  hydrogen  acids. 

3.  On  more  exact  investigation  of  the  relation  of  hydrogen-aeids  to 
metallic  oxides,  it  was  found  that,  according  to  the  idea  of  a  salt  laid 
down  in  (2).  common  salt,  notwithstanding  that  it  was  the  substance  to 
which  the  name  of  salt  was  first  applied,  could  no  longer  be  regarded  as 
a  salt,  since  in  the  crystalline  state  it  is  NaCl,  a  compound  ^  the  first 
order,  not  containing  either  base  or  acid ;  and  generally,  that  all  compounds 
of  hydrogen-acids  with  metallic  oxides  are,  when  reduced  to  the  anhydrous 
state,  no  longer  combinations  of  an  acid  with  a  salifiable  base.  Since,  how- 
ever, the  metallic  fluorides,  chlorides,  bromides,  &c.,  exhibit  a  close  resem* 


CONSTITUTION  OF  SALTS.  15 

blaooo  to  the  ozygennsalts,  tlie  three  following  methods^  described  under 
the  heads  4,  5,  and  6,  have  been  devised  to  account  for  this  resemblance. 

4.  It  is  supposed  that  common  salt,  when  in  the  dry  state,  is  not 
really  a  salt,  but  that  when  dissolved  in  water,  it  is  converted  into  the 
true  saline  compound,  hydrochlorate  of  soda ;  and  similarly,  that  all  other 
metallic  chlorides,  fluorides,  bromides,  and  iodides,  when  dissolved  in 
water,  are  to  be  regarded  as  hydrogen-nJts  of  metallic  oxides.  This  view 
has  already  been  explained  (pp.  11  ....  13). 

5.  Berzelius  distinguishes  two  classes  of  salts :  Amphid  aaUs  and 
Haloid  salts. 

The  class  of  Amphid  salts  comprises,  according  to  Berielins,  the 
oxygen-salts  (p.  5),  sulphur-salts  (p.  9),  selenium-salts,  and  tellurium- 
salts.  With  reference  to  these  compounds,  Berzelius  ca41s  the  elements, 
oxygen,  sulphur,  selenium,  and  tellurium,  by  the  name  of  Corpora  amphi- 
aenia,  Amphigenous  bodies,  that  is  to  say,  producers  both  of  acids  and  of 
bases.  (The  fluorine-salts,  (p.  8),  chlorine-salts,  (p.  9),  bromine-salts, 
(p.  9),  and  iodine-salts  may  likewise,  according  to  Bonsdoi^,  BouUay,  and 
others,  be  included  in  the  same  category,  inasmuch  as  they  are  all  compounds 
of  the  second  order.     Berzelius  considers  them  as  double  haloid  salts.) 

The  Haloid  sails  are  compounds  of  fluorine,  chlorine,  bromine,  iodine, 
and  cyanogen,  with  metals ;  the  bodies  just  enumerated  are  called  by 
Berzelius,  Salijiers,  corpora  halogenia.  When  to  any  such  haloid  salt 
there  is  added  the  hydrogen-acia  of  the  corresponding  salifier,  an  acid 
haloid  salt  is  produced,  eg,  KF,  HF.  If,  on  the  other  hand,  a  haloid 
salt  be  mixed  with  the  oxide  of  the  metal  which  it  contains,  a  basic  haloid 
salt  is  the  result,  e.g,  SbO',  SbCl'.  Finally,  when  one  haloid  salt  com- 
bines with  another  containing  either  the  same  salifier  or  the  same  metal 
as  the  former,  the  resulting  compound  is  a  double  haloid  salt  (the  compounds 
already  spoken  of  on  page  9,  as  fluorine,  chlorine,  bromine,  and  iodine-salts). 

Althouffh  common  salt  is  called  a  haloid  salt,  it  nevertheless  remains 
a  compound  of  the  first  order,  and  consequently  separated  by  as  great  a 
gulf  as  before  from  the  amphid  salts,  which  are  compounds  of  the  second 
order.  If,  again,  the  term  salt  be  likewise  extended  to  compounds  of  the 
first  order,  exact  definition  of  it  is  becomes  impracticable.  Moreover,  if 
KCy  be  considered  a  haloid  salt,  why  should  not  KS,  KSe,  and  KTe  be 
regarded  in  the  same  li^ht  ?  On  the  whole,  it  appears  more  appropriate, 
as  pointed  out  by  Bonsdorff  {Fogg.  17,  115  and  247  ;  19,  336),  to  include 
the  double  haloid  salts  in  the  class  of  amphid  salts  under  the  names  of 
fluorine,  chlorine,  bromine,  and  iodine-salts. 

6.  Binary  Theory  of  Sahs.^Sir  H.  Davy  (GUb.  54,  377)  first  threw 
out  the  suggestion  that  chlorate  of  potassa  is  not  K  0, 01 0^  but  K,  010' ; 
nitrate  of  potassa,  not  KO,NO»,  but  K,  NO*.  Dulong  {Mem.  de 
rinstitut,  ann.  1813  ....  15,  p.  cxcix;  abstr.  Schw.  \7,  230)  put  forth  the 
same  hypothesis  with  reference  to  the  sulphates  and  oxalates  ;  and  Olark 
(Ann.  Pharm.  27,  160),  Graham  {Elements, -^i^.  160 — 166),  Liebig  {Ann. 
Pharm.  26,  170),  and  Daniell  {Ann,  Pharm.  36,  32),  have  endeavoured 
to  generalize  and  support  this  theory.  Anhydrous  hydrogen-acids  redden 
litmus,  anhydrous  oxygen-acids  do  not.  It  is  not  till  water  is  added  to 
them  that  the  latter  acquire  the  property  of  reddening  litmus.  It  appears 
therefore,  that  it  is  the  water  which  converts  them  into  acids,  and,  in  fact, 
into  hydrogen-acids.  Thus,  anhydrous  sulphuric  acid,  SO',  in  contact 
with  an  atom  of  water,  does  not  become  HO,  SO',  but  the  SO' takes 
from  the  water  an  atom  of  oxygen  and  forms  SO^,  which  then  combines 


16  CONSTITUTION  OP  SALTS. 

with  the  hydrogen  of  the  water,  producing  a  hydrogen -acid,  H,SO*. 
When  H,  SO*  (oil  of  vitriol)  comes  in  contact  with  KO,  the  O  of  the 
KO  comhines  with  the  H  of  the  acid^  forming  water,  and  K,  SO*  is  pro- 
duced. In  contact  with  potassiam,  H,  SO*  is  resolved  into  H,  which 
escapes,  and  K, SO*.  The  chemical  relations  of  H, SO*  are  therefore 
precisely  similar  to  those  of  H  CI,  the  only  difference  between  these  two 
acids  being  that  the  radical  CI  of  HCl  is  simple,  while  the  radical  SO*  of 
the  acid  H,  SO*  is  compound.  This  theory  may  likewise  be  extended  to 
the  other  oxygen-acids  and  salts  :  for  example,  nitre,  according  to  this 
Yiew,  is  K,  N  O*,  &c.  &c.  Particular  names  are  required  for  the  com- 
pound radicals  :  SO*  is  called  by  Daniell,  Oxysulfion;  by  Graham,  Stdfai- 
oxygen ;  by  Otto,  Sulfarif  and  its  compounds  with  hydrogen  or  with 
metals,  Smfanides; — NO*  is  called  by  Daniell,  Oxynitrion;  by  Graham, 
Niiraioxygen ;  by  Otto,  Nitran,  Similar  names  are  applied  to  the 
remaining  radicals.  Graham  assigns  to  these  compound  radicals  the 
common  name  of  Salt-radical^  and  to  the  metal,  hydrogen,  or  ammonium 
therewith  combined,  the  name  of  the  BasyU, 

The  binary  theory  is  recommended  by  the  following  considerations  : — 

1.  It  resolves  the  amphid  salts  into  compounds  of  the  first  order, 
and  thereby  renders  them  precisely  analogous  to  the  inorganic  haloid 
salts,  with  the  sole  difference  that  the  former  contain  a  compound,  the 
latter  a  simple  radical.  The  relations  of  the  metals  and  metallic  oxides 
towards  the  hydrates  and  the  oxygen-acids  and  towards  the  anhydrous 
hydrogen-acids  become  identical.  Zn  evolves  the  same  quantity  of  hydro- 
gen gas  with  H  CI  as  with  H,  S  0*,  producing  Zn  CI  in  the  first  instance,  and 
Zn,  SO*  in  the  second.  Lime  :=  CaO  produces  equal  quantities  of  water 
with  HCl  and  with  H,  SO*, — ^and  this  water  is  in  both  cases  formed  by  the 
union  of  the  oxygen  of  the  lime  with  the  hydrogen  of  the  acid  ;  whereas, 
according  to  the  ordinary  view,  the  water  which  CaO  yields  in  contact 
with  HCl  is  a  product, — -but  that  which  is  obtained  from  CaO  and  HO, 
SO'  existed  previously,  and  is,  therefore,  an  educt. 

2.  The  decomposition  of  oxygen-salts  by  the  electric  current  is 
more  easily  explained  on  the  binary  theory  than  on  the  other.  {fJomp, 
Daniell,  vol.  i.  p.  459.) 

3.  The  binary  theory  of  salts  accounts,  to  a  certain  extent,  for  the 
three  isomeric  conditions  of  phosphoric  acid.  Hydrated  metaphosphoric 
acid,  HO, aPO*,  which  takes  up  but  one  atom  of  base,  is  H,  PO*,  and 
the  single  atom  of  hydrogen  may  be  replaced  by  one  atom  of  metal. 
Hydrated  pyrophosphoric  acid,  2H0,  5P0*  is  2H,  PO';  and  by  virtue 
of  the  two  atoms  of  hydrogen  which  it  contains,  it  decomposes  2  atoms 
of  metallic  oxide,  e.g.  NaO,  producing  2H0  and  2Na,  PO^  Lastly, 
the  hydrate  of  ordinary  phosphoric  acid,  3H0,  c  PO*  is  to  be  regarded 
as  3H,P0^  in  contact  with  3NaO  it  yields  3H0  and  3Na,  PO^ 
According  to  this  theory,  then,  the  difference  between  the  three  acids 
consists  in  this,  that  they  contain  different  salt-radicals,  viz.,  PO*,  P0% 
and  PO*,  the  first  of  which  takes  up  one,  the  second  two,  and  the  third 
three  atoms  of  metal. 

4.  The  theory  explains  why  an  atom  of  a  base  requires  as  many  atoms 
of  an  acid  to  produce  a  normal  salt,  as  the  base  itself  contains  atoms  of 
oxygen ;  viz.,  because  each  atom  of  oxygen  in  the  base  combines  with 
one  atom  of  hydrogen  in  the  acid.  As  many  atoms  of  salt-radical  as  are 
thus  set  free,  so  many  go  over  to  the  metal.  This  will  be  seen  by  refer- 
ence to  the  following  tabular  example  : — 


CONSTITUTION  OF  SALTS.  17 

Ordinarj  Sulfan  Corresponding 

Formula.  Formula.  Chloride. 

Sulphate  of  dinoxide  of  mercury  ..    Hg*0,  SO'  =  2Hg,  SO*     ....   2Hg,  CI 

Protosulphate  of  iron FeO,»  SO*  =    Fe,  SO*  '    ....   Fe,  CI 

Persulphate  of  iron Fe«0,  3S0'  =  2Fe,  3S0*    ....    2Fe,3a 

Persnlphatcoftin SnO«,2SO'  =    Sn,  2SO*    Sn,  2C1 

5.  The  decompositions  of  oxjgen-salta  by  haloid  salts  are  directly 
explained  on  this  theory  as  decompositioDS  by  double  affinity,  e,  g.  that 
of  salphate  of  potassa  by  chloride  of  bsuriam :  B%  01  +  K.  SO*  = 
Ba,SO*  +  KCl. 

6.  This  theory  likewise  explains  the  isomorphism  of  snlphate  of  soda 
and  hypermanganate  of  baryta.     (Clark,  vol.  I.  p.  92.) 

7.  Schroder  finds  that  the  Binary  Theory  of  Salts  is  more  in  accord- 
ance with  his  Theory  of  Volames  than  the  ordinary  theory*. 

[See  also  Wilson,  Quart.  Joum,  Chem,  Soc.,  1,  332.] 


The  objections  to  the  Binary  Theory  of  Salts  are  as  follows : 

1 .  It  assumes  the  existence  of  many  compounds  which  are  not  known 
to  exist  in  the  separate  state,  viz.  SO*,  NO«,PO«,  PO^  PO^  &c.,  and  thus 
encumbers  chemical  science  with  a  mass  of  hypothetical  substancest. 

2.  All  oxygen-acids  do  not  form  with  the  first  atom  of  water,  com- 
pounds which  can  be  properly  regarded  as  combinations  of  hydrogen  with 
a  salt-radical.  Thus,  in  the  case  of  carbonic  acid,  chromic  acid,  &c.,  we 
know  of  no  hydrate  which  can  be  looked  upon  as  H,  CO',  or  as  H,CrO*. 
In  such  cases,  therefore,  the  compound  of  the  salt-radical  with  hydrogen 
must  be  hypothetical,  as  well  as  the  salt-radical  itself. 

3.  It  is  not  easy  to  see  where  the  limits  of  this  binary  theory  are  to 
be  placed.  Unless  it  is  to  be  extended  to  all  oxygen-salts,  it  fails  to 
confer  the  promised  advantage  of  uniting  the  amphid  and  haloid  salts  in 
one  single  class  of  similarly  constituted  compounds.  If,  again,  the  theory 
be  extended — as  consistency  requires — ^to  all  salts,  then  not  only  must 
silicate  of  soda,  NaO,  SiO',  be  regarded  as  Na,SiO' — and  similarly  with 
the  salts  of  the  weakest  acids — ^but  likewise  Spinell,  3MgO,  APO',  must 
be  considered  as  3Mg,  AP,  0", — hydrate  of  potassa  KO,  HO,  as  K,  HO'; 
— in  short,  the  theory  must  be  extended  to  all  compounds  hitherto  consi- 
dered to  be  of  the  second  order,  whereby  a  vast  number  of  hypothetical 
compounds  will  be  unnecessarily  created,  and  great  confusion  introduced 
into  chemical  nomenclature.  Besides,  if  it  be  allowed  to  alter  the  formulse 
of  simple  salts  in  this  manner,  the  same  changes  may  with  equal  propriety 
be  made  in  those  of  the  double  salts.  For  instance,  K  O,  S  0^  +  Zn 0,  S 0' 
may  be  written:  K  -h  Zn,  2S0*,  the  result  being  a  compound  of  K,  with  a 
salt-radical  which  differs  from  other  salt-radicals  only  in  containing  an 
additional  element.  But  that  this  formula  is  not  the  correct  expression 
of  the  mode  of  combination  of  the  elements  of  the  double  salt,  will  in  all 
probability  be  generally  admitted;  but  there  is  likewise  some  reason  for 
believing  that  the  composition  of  simple  sulphate  of  potassa  is  more 
correctly  expressed  by  KO, SO*  than  by  K, SO*. 

4.  Graham  himself  {Lekrb.  2,  147)  draws  attention  to  the  doubtful 
explanation  which  this  theory  gives  oi  the  fact  that  one  atom  of  potassa 

*  Filhol  has  shown  that  the  superiority  of  the  binary  theory  in  this  respect  is  only 
apparent.— (See  Vol.  I.  p.  81.)    [W.] 

t  The  ordinary  theory  is  liable  to  the  same  objection,  though  not  to  an  equal  exteat ; 
as  far  as  actual  separation  is  concerned,  NO'  is  in  the  same  predicament  as  N  O* ;  and 
the  same  is  the  case  with  many  other  acids,  oxalic  and  acetic  acid  for  example.     [W.] 
VOL.  11.  ^ 


18  CONSTITUTION  Of  SALTS. 

can  combine  either  with  one  or  with  two  atoms  of  sulphuric  acid;  thus— 
(a)  KO,  SO'  =  K,  SO*;  (b)  K0,2S0'  =  K,S*0'.  For  these  two  salts 
we  are  obliged  then  to  admit  the  existence  of  two  different  salt-radicals 
So  likewise  one  atom  of  potassa  combines  with  1,  2,  and  3  atoms  of 
chromic  acid,  and  accordingly,  the  binary  theory  reqaires  ns  to  admit 
the  existence  of  three  different  radicals,  viz.  CrO*,  Cr'O',  and  Cr'O". 

5.  According  to  the  binary  theory,  the  class  of  acids  must  be  supposed 
to  inclade  all  hydrogen  compounds  which,  in  contact  with  metallic  oxides, 
produce  water  and  a  compound  of  the  radical  with  the  metal, — as  for 
example,  HCi  and  NaO  yield  HO  and  NaCl,  and  similarly  3H,  P0» 
and  3NaO  yield  3H0  and  Na*,  PO".  But  if  this  be  admitted,  then 
not  only  must  phosphuretted  hydrogen  and  arseniurettcd  hydrogen  (H'P 
and  H^Ab)  be  regarded  as  terbasic  acids — since  IPP  and  3CuO  yield 
3H0  and  Cu'P — but  even  ammonia,  H'N,  which  with  many  metallic 
oxides  yields  products  of  double  decomposition  (e.g.  H'N  and  3HgO 
yield  3H0  and  Hg^H),  must  be  regarded  in  the  same  light. 

G.  The  assumption  that  potassium  and  other  metals  possessing  great 
affinity  for  oxygen  can  remain  in  union  with  SO*,  NO"*,  &c.,  without 
decomposing  them,  is  improbable :  and  if  we  moreover  consider  hydrate 
of  potassa  as  consisting  of  K,  H  0*,  instead  of  K  0,  H  0,  we  must  admit 
that  even  peroxide  of  hydrogen  can  remain  in  contact  with  potassium 
without  suffering  decomposition.  All  this  implies  the  existence  of  enor- 
mously powerful  affinities  between  K  and  SO*,  NO*,  &c.,  to  overpower 
the  affinity  of  K  for  0. 

7.  It  is  commonly  stated  as  a  difference  between  inorganic  and  oi^nic 
acids,  that  the  former  contain  a  simple,  the  latter  a  compound  radical.  If 
the  binary  theory  be  adopted,  this  difference  must  vanish. 

8.  The  objections  of  Hess,  founded  upon  the  theory  of  Heat,  will  be 
found  in  Poggeiidorjf^ s  Annals,  53,  499.  Persoz  likewise  adduces  several 
arguments  against  it.     (Chim.  molecuL  815.) 

The  advocates  of  the  binary  theory  have  doubtless  been  aware  of 
these  various  objections :  at  all  events,  this  theory  has  never  been  com- 
pletely carried  out  in  detail. 


SuBDirisioN  I. 

NON-METALLIC  ELEMENTARY  BODIES. 


The  Non-metallic  Elements,  called  by  Berzelius,  Metalloids,  are,  at 
ordinary  pressures  and  temperatures,  either  gaseous :  Oxygen,  Hydrogen, 
Nitrogen,  Chlorine,  and  doubtless  also  Fluorine;  or  liquid:  Bromine;  or 
solid:  Carbon,  Boron,  Phosphorus,  Sulphur,  Selenium,  and  Iodine.  Tfaoete 
which  are  solid  are  either  transparent:  Carbon,  Phosphorus,  Sulphur;  or 
very  feebly  translucent,  and  at  the  same  time  possessed  of  the  metallic 
lustre:  Selenium,  Iodine;  or  opaque:  Boron  ^which  substance  has  hitherto 
been  obtained  only  in  the  pulverulent  state).  All  those  which  assume 
the  liquid  or  solid  state  are  non-condactors  of  electricity. 


According  to  their  chemical  relations,  they  may  be  divided  into: 
1.  Electro-negative  elements,  Oxygenaidt,  Chlcroids,  or  Supporii 


■ers  of 


OXYGEN.  19 

Comhiutkm;  Ozjgen,  Fluorine,  Chlorine,  Bromine,  Iodine,  Seleninm,  and 
Sulphur. 

2.  Electro-positive  elements,  Combvstihles  or  Metalloids  in  the  more 
restricted  sense  ;  Phosphorus,  Boron,  Carbon,  Hydrogen. 

8.  Nitrogen,  from  its  peculiar  characters,  stands  alone. 


Chapter  I. 

OXYGEN 


Priestlej.     Experiments  and  Observations  on  different  kinds  qfair.     Loo* 

don,  1775  ...1777.  2,  29 ;  3,  1. 
Priestley.     Experiments  and  Observations  relating  to  various  branches  of 

Natural  Philosophy.     London,  1779.  1,  92. 
Scheele.      Abhandlung  von  der  Lttft  und  d^em  Feiur,      Upsala  and 

Leipzig,  1777. 

New  Observations.     Crell  Ann.  1785.  2,  229  and  291. 

Lavoisier's  Memoirs.   CrelL  Chem.  J,  4, 140  ;  5, 125. — CrelL  Chem.  Ann. 

1786.  1,  33  and  136 ;  1788.   1,  354,  441,  528,  550  and  552  ;  2,  b^^ 

262,  431  and  433 ;  1789.  1,  145,  162,  260  and  323;  2,  68,  145  and 

433  ;  1790.  1,  69  and  518  ;— 1791.  1,  71. 
System  der  antiphloffistischen  Chemie,  iibers.  von  Jffermhstadt,  1808. 

1.  29  .  .  .  122. 
Berzelius.     Electro-chemical  Theory  of  Combustion.     Schw.  6,  119. 

Lehrbuch  der  Chemie,  Aufl.  3.  B.  5,  S.  46. 

Grotthuss,  on  Combustion.     Gilb.  33,  %\2.'Schw.  4,  238^— 6rt^.  58, 

345._(7iZ5.  69,  241. 
H.  Davy,  on  Flame,  Phil.  Trans.  1817.  45  and  77;  also  Schw.  20,  134 

and  175;  also  Gilb.  56,  113  and  225. 
Walden,  on  Flame.    PhU.  Mag.  J.  13,  86  ;  also  J.  pr.  Chem.  15,  283. 

On  Combustion  by  Platinum,  &c.  :  Erman,  Abhandlungen  der  Akch 
demie  der  Wissenchaftcn  in  Berlin  fur  1818  and  1819.  S.  368. — Dbbe- 
reiner.  Schw.  34,  91 ;— 38,  321  (also  GUb.  74,  269)  ;  Sehw.  89>  159 
— 42,  60  ; — 63,  465  ; — Kastn.  Archiv.  2,  225. — Further,  Ueber  neuent* 
deekte  und  hbchst  merhwurdige  Eigenschaften  des  Platins,  u.  s.  w.  Jena, 
1823.— Dulong  &  Thenard,  Ann.  Chim.  Phys.  23.  440;  also  Gilb.  76, 
%Q.—Ann.  Chim.  Phys.  24,  380  :  also  Schto.  40,  229  ;  Gilb.  76,  89 ; 
Kaetn.  Archiv.  1,  81.— Pleischl,  Schw.  39,  142,  201  and  351  (the  lattet 
also  in  GiJb.  76,  98)  ;  RepeH.  17,  97.--C.  G.  Gmelin,  Schw.  38,  515.— 
PfafF.  Schw.  40,  1.— Dana,  Sill.  Am.  J.  8,  198 ;  also  Schw.  43,  380.— 
Schweigger.  Schw.  39,  223 ;— 40,  10  and  237.— Karmarsch.  GUb.  75. 
80.— Chladni,  GUb.  61,  346  ;— 75,  98.— Stratinch.  RepeH.  21,410.— Van 
Dyk,  RepeH.  21,  235.  — Wohler.  Berzelius  4ter  Jahresbericht.  69.— 
Turner,  Ed.  Phil.  J.  11,  99;  12,  311 ;  the  beginning  also  in  Pogg.  2, 
10,— W.  Henry,  Ann.  Phil.  21,  364;  25,  416.— W.  Charles  Henry, 
Phil.  Mag.  J.  6,  354  ;  also  J.  pr.  Chcm.  5,  109  ;  abstr.  Pogg.  36,  150.— 
PhU.  Mag.  J.  9,  324 ;  also  Pogg.  39,  385  ;  also  J.  pr.  Chem.  9,  347.— 
Graham,  i^.  QuaH.  J.  ofSc.  6,  354. — Faraday,  Experimental  Researches 
in  ElectrieUy,  1,  165 ;  also  PhU.  Trans.  1834,  I.  1 ;  also  Pogg.  33,  149. 

•  The  terms  electro-negatiTe  and  clcctro-poaitiTe  mu«t  be  undcretood  ai  merely 
rdatitc.     [W.]  C  2 


20  OXYGEN. 

De  la  Rive  k  Market,  Ann.  Chim,  Ph^s.  39,  328.— De  la  Rire,  Fogg. 
46,  489  and  492  ;  Pogg.  54,  386  and  397. 


Acidifying  PrincipU,  Oxygene,  Orygenium,  Sauerstqf  (iMvomer) ;  and 
in  the  state  of  gas;  Oxi/gen  Oas,  Vital  Air  ^Condorcet),  Pure  Air, 
Feuerluft  (Scfaeele),  DepJdagitticaUd  Air  (Priestlej),  Oas  Oxygknty  G<u 
Oxygenium,  Saivergtof-goB, 

History.  The  older  chemists  regarded  atmospheric  air  as  a  simple 
snbstance  :  Scheele  and  Priestley  discoyered  that  it  consists  of  two  distinct 
kinds  of  air,  one  only  of  which  is  capable  of  snpporting  the  life  of  animals 
and  the  oombastion  of  inflammable  bodies.  The  actual  separation  of  this 
portion  of  the  air,  which  is  essential  to  combnstion  and  respiration,  waa 
effected  by  Priestley  in  1774,  and  by  Scheele  (to  whom  Priestley's  dis- 
covery was  then  unknown)  in  1775.  Immediately  afterwards,  Lavoisier 
showed  that  combnstion  consists  in  the  combination  of  the  burning  body 
with  oxygen  contained  in  oxygen  gas.  He  likewise  made  this  discovery 
the  groundwork  of  a  simple  Theory  of  Combustion,  the  Antiphlogistic 
Theory,  whereby  the  Phlogistic  Theory  of  Becher  and  Stahl,  which  sup- 
posed that  combustible  bodies  in  the  act  of  burning  do  not  take  any  thing 
np,  but  on  the  contrary,  evolve  a  hypothetical  snbstance,  called  Phlogiston, 
— a  theory  which  had  been  received  as  true  for  about  a  centuir, — ^was 
completely  overthrown.  Grotthuss,  and  more  especially  Sir  H.  Davy, 
added  to  the  existing  knowledge  of  the  nature  of  the  combustion  process, 
particularly  as  regards  flame.  E.  Davy's  discovery  of  a  preparation  of 
platinum  which  excites  the  combnstion  of  alcohol  at  ordinary  tempera- 
tures— and  a  similar  observation  of  Erman — led  D5bereiner  to  the 
discoyery,  that  finely  divided  platinum  induces  the  combustion  of  certain 
gaseous  bodies  at  ordinary  temperatures. 

Sources,  Oxygen  is  the  most  abundant  of  all  known  substances.  It 
constitutes  at  least  one-third  of  the  solid  mass  of  the  earth,  which,  so 
far  as  we  are  acquainted  with  it,  is  mainly  composed  of  metallic  oxides  and 
oxygen-salts.  Water  contains  0*89,  and  atmospheric  air  0*23  of  its  weight 
of  this  substance  :  it  is  likewise  found  in  most  organic  compounds. 

Preparation.  1.  By  heating  chlorate  of  potassa  to  low  redness.— In 
this  action,  KO,  CIO*,  is  converted,  by  parting  with  six  atoms  of  oxyeen 
(39  per  cent),  into  KCl.  The  salt  is  heated  over  charcoal  or  alcohol 
in  a  gkss  retort  connected  with  a  gas-delivery  tube  {App.  34).  According 
to  Bucholz  {Sckw.  6,  219),  the  retort  should  not  be  filled  to  more  than 
T*j-  of  its  bulk,  because  the  salt  on  fusing  swells  up  with  violence  :  hence 
also  the  heat  must  be  cautiously  applied.  Gay-Lussao  and  Humboldt 
moisten  the  salt  slightly  with  water,  in  order  that  the  vapour  evolved  at 
the  beginning  of  the  operation  may  expel  the  air  of  the  vessel.  The  gas 
obtained  from  chlorate  of  potassa  is  purer  than  that  from  any  other  source. 

IT  The  decomposition  of  the  chlorate  of  potassa  is  greatly  facilitated 
by  mixing  it  with  a  small  quantity  of  black  oxide  of  manganese  in  fine 
powder  ;  a  very  moderate  heat  is  then  sufficient  for  the  evolution  of  the 
gas.  The  oxide  of  manganese  undergoes  no  change,  but  appears  to  act 
only  by  catalysis.     This  is  the  most  convenient  of  all  methods  ofpre- 

Saring  oxygen.    The  gas  which  it  yields  cannot,  however,  be  so  implicitlj 
epended  upon  for  purity  as  that  which  is  obtained  by    the  use   of 
chlorate  of  potash  alone  :  for  the  manganese  is  often  mixed  with  particles 


OXYGEN.  21 

of  carbonaceous  matter;  and  these  become  oxidized  by  the  free  oxygen, 
and  converted  into  carbonic  acid.  But  when  absolute  pnrity  is  not  an 
object^  and  the  quantity  of  gas  required  not  very  large^  this  method  is 
greatly  to  be  preferred  to  all  others.    IT 

2.  By  ignition  of  red  oxide  of  mercury. — HgO,  when  heated  to  red- 
ness, is  resolved  into  vapour  of  mercury,  which  condenses  in  the  colder 
part  of  the  apparatus,  and  oxygen  gas  (8  p.  c),  which  escapes.  On 
account  of  the  higher  temperature  required  for  this  decomposition,  it  is 
advisable  to  coat  the  retort  (App.  34)  with  clay  previously  mixed  with 
cow-hair.  The  oxygen  gas  thus  obtained  may  be  contaminated  with 
vapour  of  hypouitnc  acid,  if  the  oxide  of  mercury  is  not  quite  free  from 
nitric  acid. 

3.  By  strong  ignition  of  pounded  manganese  (Brannstein). — The 
term  manganese  is  commonly  applied  to  several  native  oxides  of  the 
metal  of  that  name.  The  one  which  is  best  adapted  for  the  preparation 
of  oxygen  gas  is  Pyrolusite,  MnO*.  Three  atoms  of  this  substance, 
containing  Mu'O*,  are  resolved  by  heat  into  Mn'O*  and  0'  (12*3  per 
oent),  which  escapes.  Pjrrolusite  is  crystalline,  and  yields  a  grey  powder. 
ManganiUy  Mn'O',  HO,  ciystallizes  m  the  same  manner,  but  gives  a 
brown  powder.  Three  atoms  of  it,  =  Mn'O',  3U0  are  resolved  into 
MnH)'  and  one  atom  of  oxygen  (therefore  only  3  p.  c),  which  escapes 
with  the  aqueous  vapour.    Braunile  or  Hartmangan,  Mn*0',  is  amor- 

?»hous,  dense,  and  hard  :  3  atoms  =  Mn*0'  yield  Mn^O^  and  one  atom 
3'4  p.  c.)  of  oxygen  gas. — The  quantity  of  gas  actually  obtained  is 
always  smaller  than  the  calculated  quantity,  because  the  manganese  is 
mixed  with  foreign  substances.  Carbonate  of  lime  is  a  frequent  im- 
purity, and  hence  the  gas  is  often  contaminated  with  carbonic  acid, 
many  kinds  of  manganese,  especially  braunite,  likewise  contain  carbon, 
which  combines  with  oxygen  at  the  commencement  of  the  ignition,  and 
forms  carbonic  acid,  which  is  evolved.  The  oxygen  gas  must  therefore 
be  agitated  with  milk  of  lime  to  free  it  from  carbonic  acid.  The  most 
convenient  vessel  for  igniting  the  manganese  is  a  bottle  of  cast  or 
wrought  iron  (App*  35),  which  mav  be  nearly  filled  with  the  pounded* 
manganese.  To  the  mouth  of  the  bottle  is  adapted  an  iron  tube,  which 
should  be  smeared  with  loam,  driven  tight  into  the  bottle,  and  cemented 
on  the  outside  with  plaster  of  Paris.  To  prevent  the  gvpsum  from 
^dlinff  off  from  the  effect  of  the  heat,  the  iron  tube  should  be  covered 
with  blotting-paper  as  far  down  as  the  gypsum,  and  water  continually 
dropped  upon  it  by  means  of  a  dropping-bottle  (App.  36).f  For  smaU 
quantities  of  sas,  a  gun-barrel  welded  together  at  bottom,  and  connected 
with  a  gas-delivery  tube,  may  be  used  (App,  37).  Coated  ghws  retorts  of 
moderate  size  may  likewise  be  employed  (Aj^.  34);  but  they  must  be 
heated  very  gradually.  Earthen  retorts  are  utterly  useless ;  for  some  of 
them  are  porous  even  in  the  cold, — as  may  be  shown  by  immersing  them  in 
water  and  blowing  air  into  them — others  become  so  at  a  red  heat.  Henoe 
oxygen  gas  escapes  throngh  the  pores,  while  carbonic  acid  and  nitrogen 
enter  to  sujpply  its  place.     (Vol.  I.,  page  24.) 

4.  By  heating  manganese  with  an  equal  weight  of  oil  of  vitriol.— 
When  manganese  is  heated  alone,  it  is  converted  into  Mn'O^;  but  when  it 

*  It  is  much  better  to  have  the  manganese  in  small  lumps :  the  powder  frequently 
swells  up,  especially  if  it  be  not  absolutely  dry,  completely  fillmg  the  bottle  and  gas- 
delivery  tube,  and  a  considerable  quantity  of  it  is  ejected  at  the  end  of  the  tube,  caosinff 
great  inoonTenienee.     [W.] 

t  All  this  trouble  may  be  saved  by  using  a  well  fitting  tabe«    [W.l 


22  OXYGEN. 

is  heated  in  contact  with  salphuric  acid,  the  product  ja  HnO^SO*:  in  the 
hitter  case,  therefore!  the  quantity  of  oxygen  eyolved  is  greater  than  in  ih» 
former.  Pyrolusite,  MnO^  treated  in  this  manner  with  HO,  SO^  yields, 
hesides  vapour  of  water,  one  atom  (18*3  p.  c.)  of  oxygen  gas.  (jSch.  16, 
Vol.  I.)  Que  atom  of  manganite,  Mn'O^  HO,  yields  one  atom  (9  p.c.}; 
and  one  atom  of  braunite,  Mn^O',  yields  one  atom  (10  p.  c.)  of  oxygen 
ffas.  The  first  portions  of  gas  evolved  often  contain  chlorine,  partly 
because  the  manganese  is  frequently  contaminated  with  chloride  of  cal- 
cium, partly  because  the  sulphuric  acid  often  contains  hydrochloric  acid 
(A.  Vogel,  J,  pr,  Ckem.  1,  446).  The  chlorine  may  be  absorbed  by 
fusing  the  gas  through  water,  or  more  quickly,  through  milk  of  lime. 
The  most  convenient  vessel  for  the  operation  is  an  nncoated  glass  retort 
(App.  34).  The  manganese  is  put  in  first,  and  then  the  oil  of  vitriol,  the 
materials  filling  up,  at  most,  one  half  of  the  retort.  The  powder  must  be 
well  mixed  up  with  the  acid  before  the  heat  is  applied.  The  retort  is  then 
placed  upon  a  tripod,  and  adjusted  in  the  upper  part  of  the  air-furnace; 
and  the  fire,  as  well  as  the  draught,  is  very  gradually  increased  till  the 
bottom  of  the  retort  is  brought  to  a  low  red  heat.  The  retort  almost 
always  cracks  before  the  decomposition  is  complete,  in  consequence  of  the 
sulphate  of  manganese  being  deposited  in  the  solid  state  at  the  bottom, 
and  probably  expanding  more  quickly  than  the  glass :  for  this  reason,  the 
methoil  is  not  so  economical  as  it  appears  to  be  by  calculation.*  Iron 
vessels  cannot  be  used  in  this  process. 

5.  By  ignition  of  nitrate  of  potassa. — This  salt,  KO,  NO^  when 
heated  above  its  melting  point,  is  first  converted,  by  the  loss  of  two 
atoms  of  oxygen  (=15  per  cent.),  into  nitrite  of  potassa,  K  0,  N  0^ — and 
this,  when  raised  to  a  still  higher  temperature,  is  likewise  decomposed, 
evolving  a  mixture  of  nitrogen  and  oxygen  gases.  The  portions  which 
are  nearest  to  the  sides  of  the  vessel  become  most  strongly  heated,  and  are 
therefore  most  rapidly  decomposed;  particularly  as  the  silica  of  the  con- 
taining vessel  takes  up  potassa  from  the  nitre,  and  drives  out  the  whole  of 
the  nitric  acid  in  the  form  of  nitrogen  and  oxygen  gas.  From  this  cause, 
the  oxygen  gas  obtained  from  nitre  is  contaminated  with  nitrogen, 
even  from  the  beginning  of  the  operation:  moreover,  the  quantity  of 
nitrogen  continually  increases  as  the  action  proceeds,  so  that  the  gas 
obtained  is  quite  unfit  for  exact  experiments.  The  operation  may  be 
conducted  in  retorts  of  glass  or  earthenware,  either  coated  or  uncoated. 

6.  IT  B^  the  action  of  sulphuric  acid  on  bichromate  of  potassa. — 
S  parts  of  bichromate  of  potassa  and  4  parts  of  ordinary  sulphuric  acid  are 
heated  together  in  a  capacious  retort;  an  evolution  of  oxygen  gas,  easy  to 
regulate,  is  the  result.  151-5KO,  2CrO^  and  196H0,  S0»  yield  2«7-5 
Cr*0',  3S0'  -f-  KO,  S0»,  -  36HO,  -  and  240  (=  63  per  cent,  of  the 
chromate).  This  process  is  more  economical  than  the  ignition  of  chlorate 
of  potassa;  for  2  parts  of  the  bichromate  yield  as  much  oxygen  as  I  part 
of  the  chlorate.  The  residue  in  the  retort  likewise  possesses  a  certain 
yalue.     TBalmain,  Fharmaceutical  Journal,  2,  92.)  IT 

The  third  and  fourth  methods  are  the  most  economical;  and,  when  the 
operations  are  well  conducted,  and  the  carbonic  acid  properly  removed, 
the  gas  obtained  by  them  is  very  pure.  Oxygen  gas  may  be  collected 
either  over  water  or  over  mercury. 

*  The  most  oonveaient  and  economical  apparatus  that  can  be  used  in  this  process, 
at  least  for  moderate  quantities  of  material,  is  a  Florence  flask  fitted  with  a  gas-deliTery 
tube.  Heat  may.  be  applied  to  it  by  means  of  a  small  iron  pan  filled  with  sand  and 
placed  over  an  argand  lamp.     [W.] 


OXYGEN.  23 

General  RuUifor  the  Collection  and  Pre^enxUion  of  Oases, 

Since  the  vessel  in  which  the  gas  is  evolved  always  contains  air^  the 
gas  must  not  he  collected  till  there  is  reason  to  suppose  that  the  air  is 
wholly  or  nearly  expelled.  The  gas  is  conducted  from  the  generating  vessel 
through  a  bent  tube,  the  gas-delivery  tube  c  (App.  34,  35,  37),  and  made 
to  pass  through  a  liquid.  The  gas-delivery  tube  is  made  of  glass  or  lead, 
the  latter  material  being  very  convenient  on  account  of  its  flexibility :  a 
glass  tube  may,  however,  be  rendered  flexible  by  joining  two  pieces  together 
by  means  of  a  caoutchouc  connecter.  The  gas  is  conducted  into  a  liquid 
which  will  not  absorb  it  rapidly,  e,  g,  cold  or  warm  water,  solution  of 
common  salt,  mercury,  oil,  &c.,  according  to  the  nature  of  the  gas.  Over 
the  aperture  of  the  eas-delivery  tube  is  adjusted  a  glass  vessel — a  bottle, 
for  example — ^in  an  inverted  position,  so  that  the  bubbles  of  gas  as  they 
issue  from  the  end  of  the  tube  may  rise  into  the  vessel  and  displace  the 
liquid.  When  a  watery  liquid  is  used,  a  portion  of  it,  sufficient  to  occupy 
an  inch  or  two  of  the  neck  of  the  bottle,  is  generally  allowed  to  remain. 
The  bottle  is  then  closed  with  a  cork,  and  removed  from  the  liquid  with 
its  mouth  downwards.  This  contrivance  prevents  any  escape  of  the  gas, 
which  might  otherwise  take  place  if  the  temperature  should  rise  and  the 
elastic  force  of  the  gas  be  consequently  increased.  The  cork  likewise 
remains  saturated  with  moisture,  and  prevents  the  ingress  of  air  which 
might  ensue  if  the  elasticity  of  the  gas  were  diminished  by  reduction  of 
temperature.  When  gases  are  collected  over  mercury,  glass  stoppers 
smeared  with  grease  may  be  used:  these  are  likewise  applicable  when  the 
gas  is  collected  over  water. 

Oxygen  and  other  gajses  not  easily  absorbed  by  water  may  likewise  be 
collected  in  the  Gas-hoUer  (App.  38).  This  instrument  consists  of  a  hollow 
cylinder  of  sheet  copper,  divided  by  a  partition^  into  two  unequal  parts, 
tne  upper  one,  which  is  the  smaller  of  the  two,  being  open.  A  tube  ab 
open  at  both  ends,  proceeds  from  the  upper  division  nearly  to  the  bottom 
of  the  lower.  In  the  side  of  the  lower  division  near  the  bottom  there  is  a 
wide  opening  e  which  may  be  closed  with  a  screw.  A  tube  cd  litted 
with  a  stop-cock,  serves  to  let  the  gas  out  of  the  vessel.  When  the  gas- 
holder is  to  be  used,  the  aperture  e  is  closed,  the  tube  cd  opened,  and  the 
upper  division  filled  with  water.  The  water  then  flows  through  ab  into 
the  lower  division  and  fills  it  up,  while  the  air  escapes  through  cd.  When 
the  lower  division  is  completely  filled  with  water,  cd  is  closed,  e  opened, 
and  the  gas-delivery  tube  inserted  into  the  opening.  As  the  gas  issues 
from  the  tube  and  collects  in  the  upper  part  of  the  receiver,  the  water 
flows  out  by  the  aperture  e.  The  height  of  the  liquid  is  shown  in  the 
glass  tube  h,  which  communicates  above  and  below  with  the  lower  division 
of  the  gas-holder.  When  the  vessel  is  sufficiently  full,  the  gas-delivery 
tube  is  withdrawn,  the  aperture  e  closed  with  the  screw,  and  the  upper 
division  filled  with  water,  to  prevent  the  air  from  gaining  access  to  the 
gas  through  the  tube  ab,  in  case  of  a  fall  of  temperature  occurring.  To 
cause  the  gas  to  flow  from  the  tube  cd,  it  is  only  necessary  to  open  the 
stop-cock  with  which  that  tube  is  furnished,  and  keep  the  upper  division 
of  the  gas-holder  filled  with  water.  If  it  be  desirable  that  the  gas  should 
issue  under  stronger  pressure,  a  tube-funnel  may  be  screwed  into  a,  and 
kept  full  of  water.* 

*  A  much  more  convenient  form  of  the  gas-holder  is  that  in  which  the  upper  and 
lower  vessels  are  separate  from  one  another,  hut  connected  hy  means  of  two  tubes  furnished 
with  stop-cocks,  one  of  the  tubes  just  pasrng  through  the  top  of  the  lower  vessel,  the 


24  OXYGEN. 

Propertie$  of  Oxygen.  Colonrless  gaa: — Specific  gravity  (VoL  I., 
p.  279). — Refractive  power  (Vol.  I.,  p.  95). — Inflammable  bodies  bum 
in  oxygen  eas  much  more  vividly  than  in  common  air;  a  glowing  slip  of 
wood  introduced  into  it  bursts  into  flame  with  a  slight  detonation.  Nitric 
oxide  gas  mixed  with  it  produces  orange-red  vapours.  It  is  tasteless  and 
inodorous.  Animals  enclosed  in  this  gas  would  probably  live  longer  than 
in  an  equal  volume  of  confined  air. 

Combination  of  Oxygen  with  other  Bodies. 

Oxygen  is  capable  of  combining  with  all  other  known  elements,  with 
the  sin^e  exception  of  fluorine,  which  is  not  so  well  known  as  the  rest. 
Most  substances,  especially  those  of  a  decidedly  electro-positive  character, 
have  greater  afllnity  for  oxygen  than  for  any  other  substance,  and  evolve 
light  and  heat  in  combining  with  it.  The  combination  of  oxyfl;en  with 
other  bodies,  attended  in  this  manner  with  evolution  of  light  and  heat,  is 
called  Burning  or  Comlmstwn,  In  this  process,  the  oxygen  is  the  Sup- 
porter of  Combustiony — the  other  body,  the  Combustible  or  Burning  Body. 
Those  substances  which  most  resemble  oxygen,  viz.,  iodine,  bromine,  and 
chlorine  (doubtless  also  fluorine) — and  likewise  nitrogen — show  but  little 
tendency  to  combine  with  it,  and  the  combination  is  not  attended  with 
sensible  evolution  of  heat :  such  bodies  cannot  therefore  be  classed  among 
combustibles. 

The  combination  of  oxygen  with  other  bodies  does  not  always  take 
place  on  mere  contact:  heat,  light,  electricity,  compression,  expansion, 
contact  with  platinum  or  certain  other  metals,  or  with  another  body 
already  in  process  of  oxidation — is  often  necessary  to  induce  the  combina- 
tion to  take  place.     {See  Vol.  I.,  pp.  35. ...38.) 

But  few  bodies  are  capable  of  combining  with  oxygen  at  ordinary 
temperatures;  and  even  those  which  exhibit  this  capacity  lose  it  at  tem- 
peratures still  lower.  The  temperature  required  to  induce  the  combination 
of  any  substance  with  oxygen — the  Burning  Pointy  as  it  may  be  called — 
is  different,  not  only  for  different  substances,  but  even  for  the  same  sub- 
stance, according  as  the  combustion  is  to  take  place  rapidly  or  slowly. 
Thus,  phosphorus  combines  slowly  with  oxygen,  or  exhibits  slow  combustion, 
at  25**  (77  Fah.);  but  does  not  enter  into  rapid  combustion  till  raised  to 
60^  (140^  Fah.)     Charcoal  likewise  bums  slowly  below  a  red  heat. 

IdglU  rarely  brings  about  the  combination  of  oxygen  with  combustible 
bodies :  whether  in  so  doing  it  exerts  a  specific  action  or  merely  acts  by 
the  heat  which  it  produces,  is  a  question  not  yet  decided.  (See  Vol.  I., 
pp.  164....166.) 

Nitrogen  cannot  be  made  to  unite  with  oxygen  by  elevation  of  tem- 
perature, excepting  under  peculiar  circumstances ;  chlorine,  bromine,  and 
iodine,  not  at  all  by  heat,  only  by  substitution. 

Most  combustions  induced  by  Electricity  may  be  attributed  to  the 
heat  evolved  by  the  discharge  :  in  the  case  of  oxygen  and  nitrogen, 
however,  this  explanation  will  not  suffice  (I.,  429). 

Compression  of  the  oxygen  gas  does  not  appear  to  facilitate  com- 
bustion, unless  it  takes  place  rapidly,  aud  is  consequently  attended  with 
evolution  of  heat  (L,  301).  Thenard,  however,  found  that  wood  does  not 
take  fire  in  oxygen  gas  under  the  ordinary  pressure,  at  temperatures 

other  going  nearly  to  the  bottom.  The  apparatus  and  the  mode  of  using  it  are  too  well 
known  to  need  more  particular  description.  ( Vid.  Graham,  Elements,  p.  245  ;  Fownes* 
MamuU  qf  Chemistry,  p.  96;  Mitscherlicb,  Lekrb.,  I,  6.) 


COMBUSTION.  25 

1>elow  350° ;  bui  under  a  pressure  of  2*6",  combustiou  begins  at  252®. — 
On  the  other  hand,  phosphorus  in  oxygen  gas  or  common  air  exhibits 
slow  combustion  at  a  temperature  which  is  lower  in  proportion  as  the 
ffas  or  air  is  more  rarefied  ;  and  a  mixture  of  oxygen  and  phospharetted 
njdrogen,  which  under  the  ordinary  atmospheric  pressure  requires  a 
temperature  of  116'7°  to  inflame  it,  does  not  take  fire  at  118°  when  the 
density  is  increased  to  15  times  its  former  amount  ;  but  if  the  mixture, 
contained  in  an  inclined  glass  tube  standing  over  mercury,  be  rarefied 
by  setting  the  tube  upright,  combustion  takes  place  at  20  . — Dobereiner 
likewise  found  (</.  pr,  Ckem.  1,  114)  that  a  mixture  of  equal  measures 
of  oxygen,  hydrogen,  and  nitrogen  gases  contained  in  a  detonating  tube 
was  always  exploded  by  the  electric  spark,  if  the  tube  were  open  at 
the  bottom,  or  merely  closed  with  water ;  but  not  always,  when  the  tube 
was  closed  by  a  cork, — the  compression  appearing  to  offer  an  obstacle 
to  the  continuation  of  the  combustion. 

Flatinum  and  certain  other  Meldls, — ^When  a  mixture  of  oxygen  and  a 
combustible  gas  is  placed  in  contact  with  certain  solid  bodies,  com- 
bination takes  place  between  the  oxygen  and  the  stratum  of  the 
combustible  gas  immediately  in  contact  with  the  surface  of  the  body ; 
even  at  low  temperatures,  in  fact,  a  slow  combustion  takes  place.  By 
this,  the  temperature  of  the  solid  body  is  raised, — and  consequently,  the 
process  of  combustion  is  not  only  sustained  but  actually  accelerated ; 
and  at  length  the  temperature  of  the  solid  body  may  be  so  much  raised 
as  to  give  rise  to  rapid  combustion.  The  larger  the  surface  of  the  metal, 
the  more  powerful  is  its  action. 

It  was  observed  by  Sir  H.  Davy  that  a  mixture  of  oxygen  gas  or 
common  air  on  the  one  hand,  and  hydrogen,  carbonic  oxide,  defiant  gas, 
cyanogen,  or  vapour  of  hydrocyanic  acid,  alcohol,  ether,  rock-oil,  or  oil  of 
turpentine  on  the  other,  is  brought  into  a  state  of  slow  combustion  by 
contact  with  thin  platinum  foil  or  a  spiral  of  platinum  wire  heated  to  a 
temperature  short  of  redness, — ^that  the  heat  thus  developed  brings  the 
platinum  to  a  state  of  bright  ignition, — and  that,  with  certain  gases,  rapid 
combustion  at  length  ensues.  He  likewise  found,  as  had  been  previously 
observed  by  Grotthuss,  that  the  mixture  of  oxygen  and  hydrogen  gases 
heated  not  quite  to  redness  in  a  glass  tube,  passed  in  a  few  minutes  into 
the  state  of  combination  and  formed  water,  without  sensible  evolution  of 
light  and  heat.  Erman  showed  that  the  platinum  wire  requires  a  tempe- 
rature of  only  50°  to  51°  C.  in  order  to  induce  the  combination  of  oxygen 
and  hydrogen.  E.  Davy  found  that  his  platinum-black  (platinum  in  a 
state  of  division  still  finer  than  that  of  spongy  platinum),  moistened  with 
alcohol,  became  incandescent  in  the  air  and  induced  combustion  of  the 
alcohol.  Finally,  Dobereiner  discovered  that  freshly  ignited  spongy 
platinum  (as  it  remains  after  ignition  of  ammonio-chloride  of  platinum) 
excites,  even  in  the  cold,  first  the  slow,  and  then,  under  favourable 
circumstances,  the  rapid  combustion  of  a  mixture  of  hydrogen  gas  with 
oxygen  or  atmospheric  air.  It  appears  from  the  experiments  of 
Dbbereiner,  Pleischl,  and  Dulong  &  Thenard,  that  this  property  is 
possessed  ^though  in  a  less  degree,  so  that  in  most  cases  the  temperature 
must  be  raised,  though  never  to  the  burning  point),  by  other  solid  sub- 
stances, both  metallic  and  non-metallic,  e.  g,  palladium,  rhodium,  iridium, 
osmium^  gold,  silver,  cobalt,  nickel,  charcoal,  pumice-stone,  porcelain^ 
glass,  rock  crystal,  and  fluor-spar. 

These  experiments  may  be  made  in  either  of  the  following  ways : 

1.    Spongy  platinum  fastened  to  the  end  of   a  wire  is  suspended 


26  OXYGEN. 

vithin  a  gUas  flask,  which  is  then  exhausted  of  air  and  filled  with  the 
mixtare  of  oxygen  and  the  combustible  gas. — 2.  The  gaseous  mixture 
is  contained  in  a  vessel  standing  over  mercury,  and  the  spongy  platinum 
fastened  to  a  wire  is  pushed  up  into  it :  or  a  piece  of  it  is  simply 
passed  up  by  itself  through  the  mercury  into  the  gas.  The  platinum  is 
best  prepared  for  this  purpose  by  forming  a  mixture  of  moistened  clay 
and  ammonio-chloride  of  platinum,  or  of  sal-ammoniac  and  spongy  pla- 
tinum, into  balls,  and  heating  them  gently :  the  balls  thus  prepared  may 
be  used  several  times. — 3.  The  mixture  of  oxygen  or  air  with  the 
combustible  gas  is  directed  on  the  spongy  platinum  contained  in  a  glass 
dish  or  a  funnel. — 4.  The  spongy  platinum  is  attached  to  a  fine  pla- 
tinum wire  (for  this  purpose  the  platinum  wire  may  be  wound  into  a 
spiral,  or  a  loose  net  may  be  made  of  it ;  and  upon  this  a  portion  of 
ammonio-chloride  of  platinum  made  into  a  thick  paste  with  a  small 
quantity  of  water,  may  be  fastened,  and  then  ignited) ;  a  stream  of  tbe 
combustible  gas  is  then  to  be  directed  upon  it :  the  gas  is  thus  brought 
in  contact  with  the  platinum  after  first  mixing  with  the  air. — 5.  Fine 
platinum  wire  is  wound  from  three  to  eight  times  in  a  spiral  form  round 
a  thin  glass  rod  or  an  iron  wire,  the  turns  of  the  spiral  oeing  kept  very 
close  together  :  it  is  then  removed,  and  inserted  by  its  lower  extremity 
into  the  end  of  a  glass  tube,  from  which  the  combustible  gas  issues  into 
the  air ; — or  the  lower  turns  of  the  spiral  are  fixed  round  the  wick  of 
a  lamp  fed  with  a  combustible  and  volatile  liquid,  such  as  alcohol,  ether, 
or  a  volatile  oil  ; — or  again,  the  end  of  the  wire  is  inserted  into  the 
middle  of  the  wick  or  into  a  capillary  tube  into  which  the  liquid  rises. 
This  iirrangement  (5)  serves  for  the  Lamp  without  Flame  or  Glow-lamp, 
It  is  usual  to  set  fire  to  the  vapour,  and  let  it  bum  till  the  platinum  wire 
becomes  red  hot ; — then,  when  the  flame  is  blown  out,  the  wire  continues 
to  glow. — 6.  A  triangle  of  fine  platinum  foil  is  cemented  by  one  of 
its  corners  into  a  thin  glass  rod,  which  serves  for  a  handle,  and  held  (in 
some  cases  after  being  heated)  over  the  aperture  from  which  the  com- 
bustible gas  issues  into  the  air, — or  else  over  a  volatile  liquid,  such  as 
alcohol  or  ether.  ^The  greater  the  purity  of  the  ammonio-chloride,  the 
more  efficient  is  the  spongy  platinum  prepared  from  it. — As  with  pla- 
tinum, so  also  with  the  other  metals  above  named. 

Further  particulars  relating  to  this  matter  will  be  given  in  speaking 
of  the  difierent  combustible  gases,  especially  hydrogen. 

The  action  of  one  burning  substance  on  another  will  also  be  de- 
scribed under  the  head  of  Hydrogen, 

That  minute  Mechanical  Division  renders  many  substances  capable 
of  burning  at  comparatively  low  temperatures,  is  shown  by  the  following 
experiments.  When  oxide  of  nickef,  cobalt,  or  iron  is  reduced  by  hy- 
drogen gas  at  a  temperature  of  about  360^,  not  quite  amounting  to 
redness,  or  when  oxalate  of  iron  is  heated  in  close  vessels  not  quite  to 
redness,  whereby  the  iron  is  reduced  (according  to  Dobereiner,  Schw, 
62,  96,  and  Bottger,  Beitrdge,  2,  43,  oxalate  of  protoxide  of  iron  does 
not,  when  ignited,  leave  a  residue  of  pure  iron), — ^the  metallic  powder  thus 
obtained  burns  with  a  glimmering  light  on  being  exposed  to  the  air  at 
ordinary  temperatures.  If  the  heat  during  the  reduction  be  raised  to  red- 
ness, or  if  the  metal  reduced  at  a  heat  below  redness  be  afterwards 
ignited  in  hydrogen  gas,  it  will  no  longer  exhibit  spontaneous  com- 
bustibility,— possibly,  because  the  metal  when  thus  strongly  heated 
agglomerates  in  denser  masses  :  but  if  a  quantity  of  alumina  or  glucina 
be  mixed  with  the  metallic  oxide, — by  mixing  the  solution  with  that  of 


COMBUSTION.  27 

a  salt  of  alumina  or  glucina  and  precipitaliDg  by  an  alkali — ^the  metal, 
when  reduced  by  hydrogen,  even  at  a  red  heat  (provided  the  heat  has  not 
been  very  intense),  takes  fire,  on  exposure  to  the  air,  as  readily  as  that 
which  has  been  reduced  at  a  lower  temperature ;  possibly,  because  the 
interposition  of  the  earths,  which  are  not  reduced  by  the  hydrogeu, 
prevents  the  particles  of  metal  from  welding  together.  Copper  reduced 
by  hydrogen  gas  at  a  very  moderate  heat  was  likewise  observed  on  one 
occasion  to  become  covered,  on  exposure,  with  a  film  of  oxide,  without 
however  taking  fire.  Iron  reduced  by  hydrogen  gas  absorbs  several 
times  its  volume  of  carbonic  acid  gas :  it  thereby  loses  its  inflammability, 
which,  however,  it  recovers  by  being  again  heated  in  hydrogen  gas. — 
This  property  of  spontaneous  inflammability  may  be  explained  in  two 
different  ways  :  1.  The  metal  reduced  by  hydrogen  retains  a  portion 
of  this  gas  enclosed  among  its  particles ;  and,  when  exposed  to  the  air, 
it  induces  combination  between  this  substance  and  the  oxygen  of  the  air 
(after  the  manner  of  Dobereiner's  process) ;  and  the  great  heat  evolved 
in  this  combination  causes  the  metal  to  take  fire.  Against  this,  however, 
it  may  be  alleged  that  iron  reduced  from  the  oxalate  cannot  contain 
hydrogen  gas  enclosed  amongst  its  particles ;  and  even  when  the  metal 
is  thrown  into  water,  and  the  water  driven  off  by  evaporation,  spon- 
taneous combustion  is  still  produced  by  contact  of  air. — 2.  The  metal 
when  exposed  to  the  air  absorbs  the  air  mechanically,  just  as  any  porous 
body  would  do  (and  possibly  it  may  absorb  oxygen  with  peculiar 
avidity); — and  the  heat  developed  by  this  mechanical  absorption  gives 
rise  to  the  combustion.  If  the  metal  bajB  been  previously  saturated 
with  carbonic  acid  gas,  of  which  perhaps  it  absorbs  a  larger  quantity 
than  of  oxygen,  it  does  not  become  heated  by  contact  with  the  air. 
(Magnus.) — Wbhler  likewise  found  that  intimate  mixtures  of  charcoal 
and  reduced  metals  often  possess  the  property  of  taking  fire  at  a  red  heat. 

Development  of  Light  and  Heat  in  the  Combination  of  Oxygen  with  other 

bodies. 

Oxygen,  in  combining  with  electro-positive  bodies,  evolves  a  greater 
quantity  of  heai  than  any  other  substance.  [For  the  different  quantities 
of  heat  evolved  by  different  substances  during  combustion,  vide  Vol.  I., 
pp.  292...  294.]  The  quantity  of  heat  which  one  and  the  same  combus* 
tible  body  evolves  in  combining  with  oxygen  is  undoubtedly  the  same, 
whether  the  combustion  takes  place  slowly  or  quickly,  provided  only  that 
the  relative  quantities  of  the  combining  bodies  are  the  same  in  both  cases. 
In  the  case  of  slow  combustion,  however,  the  heat  is  much  less  intense, 
and  often  becomes  insensible;  because,  during  the  long  time  occupied  in 
the  combination,  the  greater  part  of  it  is  carried  away  by  conduction.  It 
may  perhaps  be  assumed  that  a  body  evolves  more  heat  in  combining 
widi  the  first  atom  of  oxygen  than  with  the  second,  &c.  &c.; — just  as, 
according  to  the  law  stated  on  page  143,  Vc^.  I.,  its  affinity  for  oxygen  is 
less  as  the  quantity  of  that  element  already  combined  with  it  is  greater. 
This,  it  must  be  observed,  is  contrary  to  Dulong*s  assertion,  that  one  part 
of  oxygen  evolves  2688  units  of  heat  in  combining  with  carbon,  and  3031 
units  in  combining  with  carbonic  oxide. — When  oxygen  previously  com- 
bined with  a  body  A  is  transferred  to  another  body  B,  the  heat  evolved 
is  less  than  that  which  would  be  developed  by  the  combination  of  free 
oxygen  with  B ;  and  the  difference  is  probably  equal  to  the  quantity  of 
heat  previously  evolved  in  the  combination  of  the  oxygen  with  A.     The 


28  OXYGEN. 

qaantity  of  heat  evohed  is  greatest  when  the  body  A,  with  which  the 
oxygen  was  previously  combined,  is  either  nitrogen,  iodine,  or  chlorine ; 
because,  in  its  combination  with  these  three  sabstanoes,  litUe  or  no  heat 
appears  to  be  evolved. 

On  the  contrary,  the  qaantity  of  Light  evolved  in  the  combination  of 
oxygen  with  a  given  quantity  of  a  combustible  body  varies  greatly 
according  to  the  rapidity  of  the  combustion.  If  the  combination  takes 
place  so  slowly,  that  the  heat  evolved  is  not  sufficiently  intense  to  raise  the 
surface  of  contact  of  the  oxygen  with  the  burning  body  to  the  point  of 
incandescence  or  gUwhpaint,  then,  generally  speaking,  no  light  is  evolved. 
The  only  exceptions  to  this  rule  are  the  slow  combustion  of  phosphorus 
and  the  phosphorescence  of  wood  and  various  other  organic  bodies  (Vol.  I., 
pp.  181....  192).  On  the  contrary,  the  higher  the  temperature  is  raised 
above  the  glow-point  by  rapid  combustion,  the  greater  is  the  quantity  of 
light  emitted  by  a  given  quantity  of  the  burning  body.  Coal  gas  gives  the 
greatest  quantity  of  light  when  the  flame  is  made  as  large  as  it  can  be 
without  occasiouing  deposition  of  carbon.  An  argand  burner  fed  with  1^ 
cubic  feet  of  coal  gas  per  hour  gives  as  much  light  as  one  candle ;  with  2 
cubic  feet,  as  much  as  4  candles ;  and  with  3  cubic  feet,  as  much  as  10 
candles :  hence  it  appears  that  a  double  quantity  of  gas  gives  a  tenfold 
quantity  of  light.     (Uraham,  Elements^  p.  426.) 

The  fire  which  accompanies  the  process  of  combustion  appears  either 
as  Glow  or  Incandescence*,  when  the  burning  body  does  not  before  com- 
bustion pass  into  the  gaseous  state, — or  as  Flame,  when  the  burning  body 
is  previously  converted  into  gas  or  vapour.  In  the  former  case,  the  heat 
evolved  at  the  surface  of  contact  of  the  oxygen  gas  and  the  solid  or  liquid 
body — charcoal  or  iron,  for  example — ^passes  into  that  body  and  heats  it  to 
redness.  The  colour  of  the  light  emitted  varies  with  the  intensity  of  the 
beat.  Feebly  glowing  coals  emit  a  dull  red  light  {Cherry-red  Mat,  dull 
or  feeble  glow) ;  when  more  strongly  heated,  they  emit  a  yellowish  red 
light  {BrigJU  or  full  red  heat)',  at  still  higher  temperatures,  a  yellow  light 
{Dvll  or  commencing  white  heat),  then  a  yellowish  white,  then  a  greenish 
white,  and  lastly,  a  bluish  white,  intensely  dazzling  light  {Bright,  full,  or 
dazzling  white  heat ;  Incandescence,  properly  so  called). 

When  the  combustible  body  is  in  the  gaseous  form— -either  originally, 
or  in  consequence  of  the  heat  required  to  cause  it  to  burn — ^the  heat  is 
developed  at  the  boundary  between  the  oxygen  and  the  combustible  gas, 
accumulating  both  in  the  new  compound  and  in  the  contiguous  portions  of 
uncombincd  oxygen  and  combustible  gas;  and  the  glowing  of  these  elastic 
fluids  exhibits  itself  in  the  form  of  Flame.  The  heat  of  flame  often  greatly 
exceeds  the  ordinary  white  heat ;  for,  according  to  Sir  H.  Davy,  a  fine 
platinnm  wire  held  at  the  twentieth  of  an  inch  from  an  alcohol  flame  still 
appears  incandescent.  Flame  consists  of  an  inner,  dark,  and  less  heated 
space  filled  with  the  combustible  gas,  and  of  a  glowing  envelope  which 
marks  the  boundary  at  which  the  combustible  body  and  the  oxygen  come 
in  contact  and  unite,  with  evolution  of  light  and  heat.  (Symm.) — A  piece 
of  phosphorus  placed  on  the  wick  of  a  spirit  lamp  will  not  bum  till  it  is 
pushed  outwaros.  If  a  piece  of  phosphorus  be  placed  on  a  wooden  sup- 
port in  the  middle  of  a  bajBin  filled  wita  alcohol,  and  the  alcohol  be  set  on 

*  This  term  Incandescence  is  commonlj  ased  in  a  general  sense  to  denote  luminosity 
produced  by  elevation  of  temperature.  It  would,  however,  be  better  to  restrict  the 
word  to  its  proper  etymological  signification,  viz.,  the  state  of  white-heat.  The  shorter 
word  Glow,  identical  with  the  German,  GlUh^en,  is  much  better  adapted  to  express 
luminosity  in  the  more  extended  sense.    [W.] 


COMBUSTION.  29 

fire,  the  pbosphorns  melts,  but  does  not  take  fire  till  the  alcohol  is  borut 
away  or  extinguished,  or  till  the  flame  is  blown  on  one  side,  or  air 
directed  upon  the  phosphorus  by  means  of  the  blowpipe.  In  a  similar 
manner,  a  lighted  candle  will  go  out  when  placed  in  the  midst  of  an 
alcohol  flame.     (Davies,  Ann.  FnU.  25,  447.) 

The  Brightness  or  Illuminating  Power  of  Flame  depends,  not  only  on 
the  degree  of  heat,  but  likewise  on  the  presence  or  absence  of  solid  parti- 
cles which  may  act  as  radiate  points.  A  flame  containing  no  such 
particles  emits  put  a  feeble  light,  even  if  its  temperature  is  the  highest 
possible — ^the  flame  of  hydrogen  gas,  for  example.  But  in  flames  which 
do  contain  solid  particles,  the  brightness  increases  with  the  temperature  to 
which  these  particles  are  raised.  Solid  particles  in  a  flame  sometimes 
arise  from  the  combination  of  the  combustible  body  with  oxygen,  e.  g. 
phosphoric  acid  or  oxide  of  zinc  in  the  combustion  of  phosphorus  or  zinc; 
sometimes,  when  the  burning  body  is  an  organic  hydro-carbon  in  the 
gaseous  state,  they  consist  of  particles  of  carbon  in  the  form  of  soot  sepa- 
rated in  the  interior  of  the  flame  by  the  heat  of  the  burning  envelope.  A 
dull  flame  becomes  brighter  by  the  introduction  of  a  solid  body  in  a  finely 
divided  state. 

Supposing  that  light  and  heat  consist  of  the  same  substance  endued 
with  difierent  rates  of  motion,  it  would  appear  that  this  substance,  to 
cause  it  to  acquire  the  higher  degree  of  velocity  necessary  to  produce  the 
effect  of  light,  requires  the  presence  of  solid  bodies  which  may  act  as 
Badiating  Centres. 

^  The  following  substances  give  a  Dull  Flame :  hydrogen  gas,  carbonic 
oxide  gas,  sulphur,  selenium,  arsenic,  alcohol— and  likewise  coal-gas  when 
it  is  mixed  with  a  suflicient  quantity  of  air  to  cause  it  to  bum  without 
deposition  of  soot :  phosphorus  also  burns  with  a  dull  flame  in  chlorine 
gas,  because  the  chloride  of  phosphorus,  which  is  the  product  of  the  com- 
bustion, remains  in  the  gaseous  state.  (H.  Davy.)  When  a  spiral  of 
platinum  wire  or  a  piece  of  asbestos  is  held  in  either  of  these  flames,  or 
some  powdered  oxide  of  zinc  thrown  into  it,  the  solid  matter  immediately 
becomes  white-hot,  and  emits  a  vivid  light.  (H.  Davy.)  Paper  soaked  in 
solution  of  chloride  of  calcium  and  burnt  in  the  flame  of  a  spirit  lamp 
leaves  a  white  network  of  ashes,  which,  when  held  in  the  feeblest  alcohol 
flame,  emits  a  brilliant  light     (Talbot,  Fhil.  Afag,  J.  3,  114.) 

DrummoncTs  Light.  Upon  a  ball  of  burnt  chalk  (quicklime),  having 
a  stem  by  which  it  is  fastened  to  a  wire,  alcohol  is  proiected  from  one  set 
of  tubes,  while  oxygen  gas  is  blown  upon  it  from  another  set.  The  alco- 
hol burning  in  the  oxygen  gas  heats  the  ball  to  the  most  dazzling  white- 
ness ;  so  thai  the  light,  when  reflected  by  a  concave  mirror  placed  behind 
it,  is  plainly  visible  at  the  distance  of  68  English  miles.  Zirconia  gives 
a  light  somewhat  less  powerful  than  that  of  lime ;  that  produced  by 
magnesia  is  only  half  as  strong.  (Drummond,  Ed.  J,  of  Sc.  5,  319;  also 
Schw.  48,  431  ;  also  Fogg.  9,  170.)  By  the  oxy-hydrogen  blowpipe  (vid. 
Hydrogen)  burnt  chalk  is  rendered  much  more  ori^htly  luminous  than  by 
alcohol  and  oxygen  gas.  Supposing  the  intensity  of  light  of  a  wax 
candle  =  1,  that  emitted  by  a  cylinder  of  lime  whose  circumference  is 
one-fifth  of  that  of  the  flame  of  the  candle,  is  equal  to  153  when  it  is 
ignited  by  the  oxy-hydrogen  flame ;  to  76,  in  the  flame  of  ether  and  oxy- 
gen ;  to  69,  in  that  of  alcohol  and  oxygen ;  and  to  19,  in  that  of  coal-gas 
and  oxygen.  Unbumt  chalk,  white  clay,  and  magnesia,  give  much  less 
light  than  burnt  chalk.     (Pfaff,  Fogg.  40,  547.)— For  experiments  with 


30  OXYGEN. 

tbe  flame  of  an  oil  lamp  fed  with  oxygeu^  also  with  oil-gas  and  oil  of  tur- 
pentine, vid.  Pleischl  {Zeitschr.  Phys,  Math,  1,  390);  Gandin  {Compt. 
rend.  6,  861 ;  also  J.  pr,  Chem,  16,  54). 

Detonating  gas,  enclosed  in  a  strong  and  perfectly  dry  glass  globe, 
gives  out  a  dazzling  light  when  exploded,  just  like  that  of  phosphorus 
bumiug  in  oxygen  gas;  if  the  density  be  doubled,  the  light  is  still 
brighter ;  but  when  the  stop-cock  is  open,  or  the  inner  surface  of  the  globe 
damp,  the  light  is  but  feeble.  (Dbbereiner,  Schw,  62,  87.)  Probably  the 
sides  of  the  vessel  become  red-hot.    (6m.) 

A  Briffht  Flarne  is  produced  by  the  following  bodies : — 

1.  Those  which  in  combination  with  oxygen  form  a  solid  compound: 
phosphorus^  potassium,  antimony,  bismuth,  zinc,  and  most  other  metals. 
(Davy.) 

2.  Compounds  containing  carbon,  from  which  a  portion  of  the  carbon 
is  separated  in  the  form  of  soot,  by  the  heat  produced  at  the  part  where 
the  combustion  actually  takes  place ;  the  separated  carbon  being  first 
brought  to  a  state  of  vivid  incandescence,  and  subsequently  burnt  when 
it  comes  in  contact  with  oxygen.  This  is  the  case  with  marsh-gas,  defi- 
ant gas,  ether,  volatile  oils,  fats,  resins,  &c.  (H.  Davy.)  The  fiame  of 
alcohol  may  likewise  be  rendered  bright  by  the  presence  of  any  substance 
which  causes  the  carbon  to  separate  from  it.  Thus,  chlorine  gas  mixed 
"#ith  the  flame  of  alcohol  increases  its  luminosity,  because,  by  combining 
with  the  hydrogen  it  causes  a  deposition  of  solid  carbon.  Vapour  of 
binoxide  of  osmium  likewise  gives  luminosity  to  the  flame  of  alcohol,  by 
giving  up  osmium  and  separating  carbon  from  the  alcohol.  To  produce 
this  efl'ect,  a  piece  of  osmium  is  laid  on  the  edge  of  a  piece  of  platinum- 
foil,  and  the  foil  held  over  the  alcohol  flame,  so  that  the  osmium  may 
bum,  and  the  vapours  of  the  binoxide  may  mix  with  the  vapour  of  alco- 
hol (Berzelius).  The  more  slowly  a  carbonaceous  substance  of  this  kind 
is  burned,  the  greater  is  the  quantity  of  carbon  separated  from  it ;  the 
brightness  of  the  fiame  is,  however,  diminished  in  the  same  proportion, 
because  the  particles  of  carbon  are  less  strongly  heated.  On  the  contrary, 
the  quicker  the  combustion, the  smaller  is  the  quantity  of  carbon  separated; 
but  the  temperature  to  which  it  is  raised  is  so  much  the  higher,  and  con- 
sequently it  emits  a  brighter  light.     (Payen,  J.  Ch,  Med.  3,  177.) 

The  flame  of  these  highly  carbonized  substances,  e.  g.  that  of  a  candle, 
consists  of  three  parts  :  (a)  The  innermost  part  consists  of  gaseous 
matter  produced  by  the  decomposition  of  the  tallow  :  this  is  at  a  tem- 
perature below  redness,  (h)  The  innermost  cone  is  surrounded  by  a  highly 
luminous  envelope  of  finely  divided  carbon  at  a  white  heat,  (c)  This 
envelope  is  surrounded  by  a  very  pale  blue  flame,  most  plainly  seen  at 
the  bottom.  This  pale  flame  marks  the  place  where  the  combination  of 
the  oxygen  supplied  from  without  with  the  combustible  matter  evolved 
from  the  interior  takes  place ;  consequently  this  is  by  far  the  hottest  part 
of  the  flame.  (Symm.  Porret,  Ann,  Phil.  8,  221;  9,  337;  compare 
Longmire,  Ann.  Phil.  11,  176  ;  Blackaddcr,  N.  Ed.  Phil.  J.  1,  52  and 
224;  Waldie,  PhU.  Mag.  J.  13,  86;  also  J.  pr.  Chem.  15,  223.) 

The  Size  of  the  Flame  is  greater  in  proportion  as  a  greater  quantity  of 
oxygen  gas  is  required  to  consume  a  given  volume  of  the  rising  com- 
bustible gas,  and  also  as  the  surrounding  oxygen  is  mixed  or  combined  to 
a  greater  extent  with  foreign  gases  ;  for  in  this  case,  the  combustible  gas 
must  present  a  larger  circumference  and  a  greater  number  of  points  of 
contact  to  the  oxygen,  in  order  that  the  latter  may  be  consumed  aa  £a.st  as 
it  is  supplied. 


COMBUSTION.  31 

When  different  combnstible  gases  are  made  to  flow  from  a  jet  in 
streams  of  given  strength  into  oxygen  gas  and  mixtures  containing  it,  the 
following  effects  are  observed  :  Hydrogen  gas  gives  a  much  smaller  flame 
than  oletiant  gas  (1  volume  of  hydrogen  requires  half  a  volume  of  oxygen, 
and  1  volume  of  defiant  gas  requires  3  volumes  of  oxygen  to  bum  it). 
Hydrogen  gas  mixed  with  nitrogen  gives  a  still  smaller  flame  than  pure 
hydrogen.  The  flame  of  hydrogen  gas  in  oxygen  is  smaller  than  that  of 
the  same  gas  in  air ;  but  there  is  this  anomaly  observed,  that  hydrogen 
gives  a  smaller  flame  in  air  than  it  does  in  chlorine  or  nitrons  oxide  gas, — 
although  1  volume  of  hydrogen  gas  requires  2*4  volumes  of  air  and  only 
one  volume  of  chlorine  or  of  nitrons  oxide  gas.  This  peculiarity  is  pro- 
bably due  to  the  different  degrees  of  diffusibility  of  the  gases  through 
each  other.     (Waldie.) 

Tfie  Colour  of  the  Flame  depends  partly  on  its  temperature,  partly  on 
the  nature  of  the  substances  contained  in  it. 

Cold  carbonic  oxide  gas  gives  a  blue  flame  in  burning;  but  if  it  has 
previously  been  heated,  it  gives  a  yellowish  red  flame.  Hydrogen  and 
other  gases  which  in  burning  evolve  more  heat  than  is  evolved  by  car- 
bonic oxide^  exhibit  a  yellowish  red  flame  even  when  set  on  fire  in  the 
cold.  But  when  hydrogen  gas  issues  from  a  fine  jet  (as  in  Marsh's 
apparatus)  against  a  porcelain  slab  held  close  in  front  of  it,  a  pale  green 
flame  is  produced, — possibly  in  consequence  of  the  cooling  action  of  the 
porcelain.  The  blue  flame  at  the  lower  part  of  the  flame  of  a  candle 
likewise  indicates  a  comparatively  low  temperature.  It  is  remarkable 
that  in  the  glowing  combustion  of  solid  bodies  the  colours  exhibit  exactly 
the  opposite  relation  (p.  28). 

The  addition  of  boracic  acid,  or  of  a  metallic  chloride  and  oil  of  vitriol 
to  alcohol,  gives  the  flame  a  green  colour — or,  when  it  is  more  strongly 
heated,  turns  it  yellow.  Chloride  of  strontium  or  chloride  of  calcium 
colours  the  flame  of  alcohol  red;  chloride  of  barium,  or  common  salt, 
colours  it  yellow ;  proto-chloride  of  copper  gives  it  a  bright  red  colour, 
with  green  and  blue  edges.  Copper  covered  with  oxide  or  sulphide  (but 
not  clean  copper)  held  in  the  flame  of  alcohol,  colours  it  green.  (Mulder, 
jr.  Br,  Arch,  2,  145.)  The  flames  of  other  burning  bodies  undergo 
similar  alterations.  Chloride  of  strontium  reddens  the  flame  of  hydrogen, 
marsh-gas,  and  defiant  gas,  as  also  that  of  a  candle — but  only  so  long  as 
the  salt  itself  remains  moist ;  on  the  flame  of  sulphur  it  has  no  effect. 
(Hiinefeld,  Schw.  60,  383;  J.  pr,  Chem.  7,  234.^  In  all  these  cases,  a 
portion  of  the  added  substance  undoubtedly  volatilizes :  but  whether  it 
volatilizes  nndecomposed,  so  that  the  colour  of  the  flame  is  altered  merely 
by  the  presence  of  boracic  acid,  chloride  of  strontium,  chloride  of  copper, 
&c.,  or  whether  decomposition  takes  place,  so  that  boron,  strontium, 
calcium,  barium,  or  copper  is  introduced  into  the  flame  in  the  reduced 
state — is  there  burnt — and  thereby  produces  a  different  colour — is  a 
question  not  yet  decided.     Sir  H.  Davy  suggested  the  latter  explanation. 

In  ordinary  flames,  the  combustible  gas  occupies  the  interior,  and  is 
surrounded  with  atmospheric  air  or  oxygen  gas.  But  the  combustion 
may  likewise  be  sustained  by  directing  a  stream  of  oxygen  gas,  air,  &c. 
into  a  vessel  filled  with  the  combustible  gas.  The  interior  dark  part  of 
the  flame  then  consists  of  oxygen  gas ;  and  this  gas  seems,  as  it  were,  to. 
burn  in  the  combustible  gas.  In  this  manner,  oxygen  gas  (and  also 
chlorine)   may  be  made  to  burn  in  hydrogen;   likewise,  oxygen  gas, 


32  OXYGEN. 

common  air,  vapour  of  byponitric  acid  (or  chlorine  gas,  with  hirge  depo- 
sition of  soot)  in  defiant  gas.  To  produce  this  effect,  a  stoppered  bell-jar 
standing  over  water  is  filled  with  defiant  gas — the  stopper  removed — ^the 
gas  set  on  fire — and  the  oxygen  tube,  which  is  fitted  into  a  cork,  plunged 
into  the  defiant  gas— the  cork  serving  to  close  the  aperture.     Or  a 

anantity  of  chlorate  of  potash  contained  in  a  small  basin  suspended  from 
le  cork  may  be  heated  till  it  evolves  oxygen  gas,  and  then  plunged  into 
the  defiant  gas  previously  set  on  fire  at  the  mouth  of  the  jar :  the  com- 
bustion then  goes  on,  producing  a  beautiful  light,  the  colour  of  which 
may  be  variously  modified  by  the  addition  of  nitrate  of  soda,  strontia,  or 
copper  (Kemp, «/.  Pharm.  20,  413;  also  J,  pr,  Ckem.  3,  44). 

The  flame  of  oxygen  in  hydrogen  gas  is  green,  even  when  both  gases 
are  qnite  pure :  that  of  oxygen  in  marsh-gas  is  yellow.  The  first-men- 
tioned flame  is  much  larger  than  the  other,  because  a  measure  of  oxygen 
gas  requires  two  measures  of  hydrogen,  and  only  half  a  measure  of  marsh 
gas  (Hess,  Pogg.  44,  336;  also  J.  pr.  Chem,  13,  516). 

The  flame  is  smaller  when  oxygen  or  nitrous  oxide  gas,  or  vapour  of 
hyponitric  acid  (or  chlorine  ^as)  is  made  to  pass  into  hydrogen  gas,  than 
in  the  contrary  case :  accordmg  to  what  was  said  on  page  30,  the  con- 
trary might  have  been  expected.  A  much  smaller  flame  is  produced 
when  oxygen  passes  into  defiant  gas  than  when  it  passes  into  hydrogen. 
With  defiant  gas,  the  flame  is  dark  within, — then  follows  a  brilliant 
envelope,  hot  enough  to  melt  platinum, — then,  towards  the  outside,  a 
dark  yellow  flame,  lengthening  above  and  containing  soot,  the  greater 
part  of  which  remains  unburnt.  When  oxygen  gas  is  blown  into  boiling 
sulphur,  a  yellow  flame  is  produced,  dark  within,  red  on  the  outside  and 
at  the  apex :  air  gives  a  smaller  flame  than  oxygen,  dark  within,  blue 
without,  and  red  at  the  apex  (Waldie,  Phil,  Mag,  J,  1 3,  86). 

The  Blovhpipe  Flame  must  also  be  mentioned  in  this  place,  inasmuch 
as  the  air  is  blown  into  the  middle  of  the  ascending  combustible  vapour. 
The  strongest  heat  exists  at  that  part  of  the  flame  where  the  dark  cone 
of  injected  air  terminates  in  a  bluish  vertex,  and  the  burning  envelope 
which  snrronnds  it  concentrates  itself  npon  a  single  point. 

When  the  slow  or  rapid  combination  of  a  body  with  oxygen  has  once 
been  set  up  by  elevation  of  temperature,  the  continuance  of  this  combina- 
tion, after  the  supply  of  heat  from  without  has  been  withdrawn,  depends 
in  general  on  the  following  condition; — whether  the  quantity  of  heat 
which  the  body  in  combining  with  oxygen  evolves  in  a  given  time,  is 
equal  to  that  wuich,  in  the  same  time,  is  carried  away  by  surrounding 
bodies;  and  consequently,  whether  the  body  remains  at  the  temperature 
necessary  for  combustion; — ^and  in  particular:  1.  On  the  difference 
between  the  temperature  at  which  the  body  will  combine  with  oxygen, 
tapidly  or  slowly,  and  the  external  temperature ;  2.  On  the  quantity  of 
heat  which  it  evolves  in  burning;  3.  On  the  rarefiekction  or  condensation 
of  the  oxygen  gas;  4.  On  the  greater  or  smaller  admixture  of  foreign 
gaseous  bodies  not  contributing  towards  the  combustion;  5.  On  the 
presence  of  liquid  or  solid  heat-conducting  bodies. 

1'*.  Iron  and  diamond  require  a  wliite  heat  to  make  them  bum 
rapidly  :  hence,  when  heated  in  the  air  till  they  begin  to  bum,  the  com- 
bustion ceases  as  soon  as  the  access  of  heat  from  without  is  discontinued ; 
whereas  sulphur  and  other  easily  inflammable  bodies  continue  to  burn. 

*  The  accented  numbers  at  the  head  of  this  and  the  four  following  paragraphs  refer 
to  the  numbers  in  the  preceding  paragraph. 


COMBUSTION.  33 

2'.  Carbonic  oxide  esa,  which  is  as  easily  inflammable  as  hydrogen, 
does  not  exhibit  lapid  combustion  after  it  has  been  rarefied  to  about 
one-fonrth  of  its  ordinary  density,  because  it  eyolyes  less  heat  during 
combustion.     (H.  Davy,  vwfo  p.  292,  Vol.  T.) 

3^  A  certain  degree  of  rarefaction  preyents  the  continuance  of 
combustion;  because  combination,  and  therefore,  also,  deyelopment  of 
heat,  is  retarded  by  it.  Detonating  gas,  (a  mixture  of  two  measures  of 
hydrogen  gas  and  one  of  oxygen,)  when  rarefied  to  -^  of  its  ordinary 
density,  no  longer  explodes  by  the  electric  spark.  (H.  Davy.)  Hydro- 
gen gaS;  mixed  with  air  in  the  right  proportion,  will  not  take  fire  under 
an  external  pressure  of  5  inches.  (Grotthuss.)  Hydrogen  gas  issuing 
from  a  jet  into  the  air  exhibits  rapid  combustion  under  a  fourfold  rare- 
auction  of  the  air,  burning  even  with  a  larger  flame  than  before,  but  is 
extinguished  when  the  density  is  reduced  to  between  -^  and  \  of  its 
ordinary  amount. 

The  burning  yapour  of  alcohol,  ether,  or  wax,  is  extinguished, 
under  these  circumstances,  by  a  fiye  or  sixfold  rarefaction,  sulphuretted 
hydrogen  by  a  seyenfold  rarefaction  of  the  air.  Sulphur  continues  to 
exhibit  rapid  combustion,  even  when  the  air  is  rarefied  15  times; 
phosphorus,  when  the  density  is  reduced  to  -^  ;  while  the  easily  inflam- 
mable yariety  of  phosphnretted  hydrogen  gas  produces  a  flashing  light, 
even  in  the  best  vacuum  that  can  be  made  with  the  air-pump.  Vapour 
of  ether  in  air  rarefied  80  times,  still  produces  a  feeble  flame  on  the 
introduction  of  a  red-hot  iron.  Slow  combustion  on  the  surface  of 
platinum  is  exhibited  by  marsh-gas,  down  to  a  fourfold  rarefaction  of 
the  air ;  by  carbonic  oxide,  to  sixfold;  by  vapour  of  alcohol,  ether,  or 
wax,  to  eightfold ;  by  defiant  gas,  to  ten  or  elevenfold ;  by  hydrogen 
gas,  to  thirteenfold ;  and  by  vapour  of  sulphur,  down  to  twentyfold 
rarefaction  of  the  air.  By  elevation  of  temperature,  the  limits  of 
inflammability  are  still  further  extended ;  so  that  detonating  gas 
rarefied  18  times  and  heated  to  redness,  exhibits  a  light,  as  if  from 
combustion,  on  the  passage  of  an  electric  spark.  (H.  Davy. )  According 
to  Grotthuss,  on  the  contrary,  inflammability  is  diminishea  by  heating, 
provided  the  heat  can  produce  expansion  ;  bo  that,  for  example,  a 
mixture  of  hydrogen  gaa  and  air  expanded  in  the  Torricellian  vacuum, 
to  such  a  degree  only  that  it  would  be  inflammable  by  the  electric 
spark  at  ordinary  temperatures,  loses  its  inflammability  when  still 
further  expanded  by  heat.  Grotthuss  therefore  concludes  that  when 
expansion  can  take  place  freely,  heat  possesses  the  power  (1)  of  expand- 
ing the  body  and  therebjr  diminishing  its  inflammability ;  ^2)  of  inducing 
it  to  take  fire.  He  also  infers  that  the  expansion  takes  place  according 
to  an  arithmetical,  the  increase  of  inflammability  according  to  a  geome- 
trical progression  ;  and  that,  consequently,  at  a  certain  degree  of  heat, 
which,  howeyer,  when  the  gaseous  mixture  has  been  previously  expanded 
in  the  Torricellian  vacuum,  must  be  very  considerable,  the  latter  must 
gain  the  victory.  Davy,  on  the  contrary,  found  that  detonating  gas 
standing  over  mercury,  and  gradually  heated  till  it  was  expanded  to  2^ 
times  its  original  volume,  was  inflamed  as  the  temperature  ultimately 
reached  a  red  heat:  he  supposes  that  in  Grotthuss'  experiment  the 
combustion  was  prevented  by  the  presence  of  aqueous  or  mercurial 
vapour. 

4'.  Foreign  gaseous  bodies,  which  contribute  nothing  to  combustion, 
absorb  a  portion  of  the  heat  generated  by  the  combination,  and  reduce 
the  temperature  below  the  burning  point,  the  rapidity  of  their  action 
VOL.  n.  » 


34  OXTOBN. 

being  proportional  to  their  qaantityi  mobility,  and  oapadtj  for  heat 
Not  only  do  bodies  in  general  bum  more  rapidly  in  oxygen  gas  than  in 
atmospheric  air,  which  contains  only  one  volume  of  oxygen  to  four  of 
nitrogen ;  but  iron  and  diamond,  which,  when  once  set  on  fire,  continue 
to  bum  in  oxygen  gas,  are  immediately  extinguished  in  atmospheric 
air.  In  air  four  or  five  times  compressed — which,  therefore,  contains  ono 
Tolume  of  oxygen  gas — candles,  hydrogen  gas,  sulphur,  charcoal,  and 
iron,  do  not,  in  consequence  of  the  abstraction  of  heat  by  the  nitrogen, 
burn  more  rapidly  than  they  would  in  uncompreeeed  air,  to  which  |-  of  a 
volume  of  oxygen  had  been  ailded.  One  volume  of  detonating  gas  losee 
its  power  of  taking  firo  by  the  electric  spark,  if  there  be  added  to  it 
^  a  volume  of  olefiant  gas,  f  of  a  volume  of  fluoride  of  silicium,  1  volume 
of  marsh-gas,  ?.  volumes  of  hydrosulphuric  or  hydrochloric  acid  gas,  8 
volumes  of  hydrogen  in  excess,  9  volumes  of  oxygen  in  excess,  or  1 1 
volumes  of  nitrous  oxide :  5  measures  of  aqueous  vapour  do  not  destroy  the 
inflammability  of  1  measure  of  detonating  gas.  (H.  Davy.)  According 
to  Humboldt  and  Gay-Lussac  (Gilh,  20,  49),  the  inflammability  of  one 
volume  of  detonating  gas  is  destroyed  by  the  admixture  of  5  volumes  of 
oxyeen,  or  4 '7  volumes  of  hydrogen  gas.  Marsh-gas  is  no  longer  inflam- 
mable by  the  electric  spark,  when  it  is  mixed  with  11  measures  of 
oxygen  instead  of  the  2  measnree  which  it  actually  requires  to  combine 
with  it.  (H.  Davy.)  OmiI  gas  bums  continuously  in  a  mixture  of  1 
measure  of  oxygen  and  7  of  nitrogen,  bat  is  extinguished  when  the 
quantity  of  the  latter  amounts  to  8  measures ;  it  bums  in  a  mixture  of 
I  measure  of  oxygen,  with  3,  but  not  with  4  measures  of  hvdrochlorte 
acid  gas  ;  with  2^,  but  not  with  ^  measures  of  carbonic  aciti ;  with  2, 
but  not  with  2|  measures  of  fluoride  of  siliciam.  The  greater  the  density 
of  the  inactive  gas,  the  smaller  is  the  quantity  which  suffices  to  stop 
the  combustion  ;  because  the  combustible  gas  difi*uses  itself  more  readily 
through  a  heav^  than  through  a  light  gas,  and  therefore  cools  down  the 
faster.  (Waldie.)  A  lighted  candle  is  extinguished  in  air  to  which  ^ 
of  its  volume  of  hydrochloric  acid  gas,  or  -^  of  fluoride  of  silicium  haa 
been  added.  When  eombustible  bodies  burn  in  a  confined  space,  the 
relative  quantity  of  nitrogen,  Sec  becomes  increased,  partly  by  consump- 
tion of  oxygen,  partly  by  formation  of  gaseous  products  of  combustion, 
such  as  carbonic  acid,  sulphurous  acid,  &c. ;  and  thus  the  combustion  is 
brought  to  an  end.  In  one  and  the  same  limited  space,  a  candle  goes 
out  first,  then  hvdrogen  gas,  then  sulphur;  while  the  slow  combustion  of 
phoephoras  will  go  on  as  long  as  the  smallest  quantity  of  oxygen 
remains.     (H,  Davy.) 

5^.  Solid  burning  bodies  are  extinguished  when  laid  on  good-eon - 
ducting  supports,  e.  ff,  glowing  coals  on  considerable  masses  of  metal. — 
A  mixture  of  combustible  gases  and  oxygen  will  not  take  fire  in  very 
narrow  tubes,  because  their  sides  cool  down  too  quickly  (this  is  the 
principle  of  Newman*6  oxy-hydrogen  Mow-pipe).  From  the  same  cause, 
the  flame  of  a  mixture  of  combustible  gases  and  common  air  i»  often 
unable  to  pass  through  the  meshes  of  wire-ga«Ke  :  the  passage  of  the 
flame  takes  place,  however,  with  greater  facility,  the  lower  the  temper- 
a-ture  at  which  the  gas  takes  fire,  the  greater  tiie  heat  evolved  hj  its 
combustion,  the  more  quickly  it  is  foixwd  through  the  apertures  by  ]^!es- 
sore  or  draught,  the  wider  the  meshes,  the  smaller  the  mass  and  specific 
heat  of  the  metal  of  which  the  gauze  is  made,  and  the  higher  its  tem- 
perature. Above  a  certain  temperature,  all  flames  pass  through  it. — On 
this  impenetrability  of  wire-gause  by  the  flame  of  light  ^mrburetted  . 


COMBUSTION.  9i 

by^gen  gM  oc^arring  id  ooftl-'miDe*,  is  hued  the  Sqfetp4atnp  of  Sir  H. 
Mivjr  (Ann.  Phil.  25,  Ui).^1\xp  flame  of  a  eotton  thread  may  be  ex* 
tinguisbed  bj  holding  over  it,  even  at  some  dietaooe,  a  v'vag  of  line  iron 
wire  or  a  thicker  ring  of  glaas.    (H.  Davy.) 

According  to  McKeever  {Ann.  Phil.  20,  344 ;  also  Schw,  48,  42),  9t 
WKJL  or  tallow  caudle  bums  oat  more  quickly  in  the  dark  than  in  £<in- 
shine,  although  under  the  latter  circumstances  the  temperature  is  much 
higher. 

Motion  of  the  air  produced  by  draught  or  by  the  bellows  accelerates 
combustion,  and  thereby  increases  the  intensity  of  the  heat, — inasmacii 
as  it  continually  brings  fresh  portions  of  air  in  contact  with  the  burping 
body, 

Windr-furnace;  Blaat-fumace,  Sefstr5m's  blast-furnace  (Pogg,  15, 
(112),  altered  by  Mohr  for  operations  on  the  small  scale  {Ann,  Pharm* 
27j  229),  is  peculiarly  well  adapted  for  chemical  pur])o6es. 

For  burning  any  substance  in  a  confined  space  with  continual  renewal 
of  air,  and  collecting  the  product  of  the  combustion,  Brunner^s  Aspirator 
(Pogg.  38,  264) — an  apparatus  which  is  applicable  to  a  variety  of  pur- 
poses— may  be  conveniently  employed.  It  consists  generally  of  a  vessel 
filled  with  water.  The  water  is  let  out  at  the  bottom  ;  and  as  it  escapes, 
air  enters  at  the  upper  part,  having  been  previously  made  to  pass  over 
the  substance  which  is  to  be  submitted  to  its  action  (A  pp.  SO).  When 
all  the  water  has  run  out,  the  vessel  must  be  refilled  by  the  middle  tube. 
Modifications  of  the  apparatus  have  been  made  by  Abendroth  (Pogg* 
53,  617),  and  Bolley  (Ann,  Pkarm.  41,  322). 

Very  rapid  motion  of  the  air  may  extinguish  a  burning  body,— 
either  by  cooling,  if  the  quantity  of  air  supplied  in  a  given  time  is  such 
that  the  burning  body  cannot  in  that  time  consume  the  whole  of  its 
pxygen  ;  e.  g.  in  the  case  of  red-hot  coke  ;  or  by  blowing  the  burning 
vapour  away  from  its  source,  so  that  the  flame  can  no  longer  com- 
municate  with  the  fresh  matter  which  issues :  e.  g,  the  extinction  of  i^ 
taper. 

Fire-extinguikfivng  substances  act  either  by  cooling,  as  water  dees,"— 
or  by  covering  the  burning  borly,  and  thereby  impeding  the  fl^^cw  9f 
9ir  :  e.  g.  saline  solutions,  loam-water^  ^c. 

By  the  most  exact  experiments,  first  instituted  by  Lavoisier,  i^  has 
been  established,  that  in  combustion  the  whole  of  t^  ponderable  matter 
in  the  oxygen  gas  combines  with  the  whole  of  the  ponderable  matter  ia 
the  burning  body;  so  that  the  new  substajaoe  produced  by  the  «oiii- 
biistion — the  burnt  body — weighs  exactly  as  much  as  tlie  oxygen  g«« 
eonsumed  and  the  combustible  body  consumed  taken  together.  This  if 
the  Antiphlogistic  Theory  of  Combustion. 

The  establishment  of  this  theory  overthrew  the  Pklogitiie  Docirine 
of  Stahl  and  others,  according  to  which  it  was  assumed  that  every  com- 
bustible body  is  composed  of  Phlogiston — a  peculiar,  imponderable 
principle  of  combustibility,  common  to  all  bodies — and  an  acid  or  earthy 
substance  (e.  g.  phosphorus,  of  phlogiston  and  phosphoric  acid  ;  lead  of 
phlogiston  and  lead-earth  or  calx  of  lead,  the  substance  now  called  oxide 
of  lead^  ;  that,  when  combustion  takes  place,  the  phlo//iston  escapes  and 
the  suostanoe  with  which  it  was  combined  remains  in  the  form  of  the 
earthy  matter ;  that,  on  heating  the  burnt  body  in  contact  with  char- 
coal, a  body  very  rich  in  phlogiston,  the  burnt  body  again  takes  phlo^ 
giston  from  the  charcoal  and  is  restored  to  the  state  4>f  a  eombtt8tibk» 

b  2 


.ie  OXYGKK. 

body.  In  short,  wherever  the  present  theory  asserts  that  a  body  takes 
np  oxygen,  the  former  theory  assumed  that  it  parts  with  phlogiston ; 
and  wherever,  according  to  the  present  view,  oxygen  is  taken  from  a 
body,  it  was  supposed,  according  to  the  former  view,  that  phlogiston 
16  added  to  it.  If  the  phlogistic  doctrine  were  true,  the  body  which 
remains  after  combustion  ought  to  weigh  less  than  the  combustible  body — 
which  is  contrary  to  fact.* 

It  now  only  remains  to  investigate  the  cause  of  the  development  of 
light  and  heat  in  combustion. 

1.  Lavoisier  attributed  it  to  the  latent  heat  which  imparts  the  gaseous 
form  to  the  ponderable  part  of  oxygen  gas — ^the  oxygen,  properly  so 
called — and  is  separated  during  the  combination  of  the  oxygen  with 
other  bodies.  That  this  assumption  is  inadmissible,  is  evident  from  what 
was  said  on  page  297,  b,  Vol.  I. 

2.  It  is  supposed  that  simple  substances  contain,  independently  of  the 
heat  of  fluidity  which  may  belong  to  them,  another  and  larger  quantity 
of  heat  still  more  intimately  combined ;  and  that  this  latter  Quantity  is 
set  free  when  they  enter  into  combination  with  ponderable  boaies.  This 
view  of  the  matter  resolves  itself  into  three  others. 

a.  The  oxygen  alone  contains  heat  thus  intimately  combined,  and  gives 
it  up  on  combining  with  combustible  bodies.  Brugnatelli  makes  a  dis* 
tinction  between  oxygen  properly  so  called — the  ponderable  body  in  fact— 
and  therm^xygen,  or  oxygen  containing  intimately  combined  heat  or  fire. 
Oxygen  gas  he  supposes  to  be  therm-oxygen  combined  with  heat  of  fluidity, 
which  gives  it  the  gaseous  form.  In  nitre,  chlorate  of  potash,  &c.,  the 
the  therm-oxygen  is  supposed  to  have  parted  with  its  heat  of  fluidity,  but 
to  have  retained  this  more  intimately  combined  heat ;  but  when  oxygen 
is  transferred  from  these  compounds  to  carbon,  phosphorus,  sulphur, 
metals,  &c.,  the  intimately  combined  heat  is  set  free,  and  consequently 
the  compounds  formed  by  the  combustion  of  these  substances  contain 
merely  the  oxygen,  separated  from  all  the  heat  with  which  it  was  asso- 
ciated. In  support  of  this  theory,  we  might  adduce  the  observation  of 
Welter  (I.  294),  viz.  that  a  pound  of  oxygen  evolves  the  same  quantity 
of  heat  whether  it  combines  with  the  equivalent  quantity  of  hydrogen  or 
of  carbon.  Since,  however,  in  the  combination  of  oxygen  with  other 
combustible  bodies,  different  quantities  of  heat  are  evolved,  Brugnatelii's 
theory  cannot  be  true, — excepting  on  the  supposition  that,  in  the  combi- 
nation of  oxyfi^en  with  various  combustible  bodies,  the  heat  which  be- 
longs to  it  (independently  of  the  heat  of  fluidity)  is  sometimes  more,  some- 
times less  completely  set  at  liberty;  and  consequently,  a  quantity  of  it, 
variable  according  to  the  nature  of  the  combustible  body,  remains  behind 
in  the  new  compound. 

b.  The  intimately  combined  heat  exists  only  in  the  combustible  body, 

*  The  advocates  of  the  phlogistic  theory  endeavoured  to  get  over  this  difficulty  by 
ascribing  to  phlogiston  a  principle  of  absolute  Levity.  Now,  however  improbable  such 
a  supposition  may  be,  it  by  no  means  involves  an  absurdity :  for  this  suppoBcA  principle 
^f  levity  would  simply  amount  to  a  tendency  to  recede  fipom  the  earth,  instead  of  ap- 
proaching it  as  ponderable  bodies  do;  and  no  one  can  say  that  the  existence  of  a  body 
having  such  a  tendency  is  an  impossibility.  The  real  superiority  of  the  antiphlogistic 
theory  consists  in  this :  that  it  ascribes  the  observed  increase  of  weight  to  the  addition 
of  a  real,  tangible  substance,  which  can  actually  be  separated,  colIe<^ed,  and  weighed ; 
whereas,  the  phlogistic  theory  was  obliged  to  rest  its  conclusions  on  the  existence  of  a 
substance  purely  hypothetical.   [W.] 


DEVELOPMENT  OP  LIGHT  AND  HEAT.  S? 

and  is  set  free  wben  that  body  combines  with  oxygen.  This  was  the  idea 
of  Wiegler,  who  thereby^  to  a  certain  extent,  endeaToured  to  rescue  the 
notion  of  phlogiston,  by  supposing  it  to  be  the  same  as  intimately  com- 
bined heat. 

c.  The  intimately  combined  heat  exists  in  all  elementair  bodies, 
both  combustibles  and  supporters  of  combustion.  In  the  act  of  combus- 
tion, both  the  heat  thus  combined  with  the  oxygen  and  that  combined 
with  the  combustible  body  is  set  free.  This  theory  has  much  probability 
in  its  favour. 

3.  EUctro-<ikemic(d  Theory  of  Combustion,  Oxygen  contains  one  kind 
of  electricity  in  a  state  of  combination  ;  the  combustible  body,  the  other 
kind.  In  the  act  of  combustion,  the  two  electricities  unite  and  form 
heat.  Views  of  this  kind  were  first  enunciated  by  Wilkie  {Crell.  Ann. 
1788,  1,  414),  afterwards  by  Grotthuss  (Ann.  Ckim.  63,  34). 

a.  Oxygen  contains  negative  electricity  in  combination;  the  com- 
bustible body,  positive  electricity.     (Berzelius.) 

b.  Oxygen  contains  positive,  the  combustible  body,  negative  elec- 
tricity. This  is  the  hypothesis  adopted  in  the  present  work  (I.,  157,  342, 
431);  it  does  not,  however,  preclude  the  idea  of  the  simultaneous  libera- 
tion of  heat  or  caloric  previously  existing  in  the  body  in  a  state  of  inti- 
mate combination,  as  described  in  2,  c. 

The  following  less  tenable  theories  of  combustion,  some  phlogistic, 
others  antiphlogistic,  have  also  been  advanced. 

1.  Gren  and  Wiegler  :  The  combustible  body  consists  of  the  substance 
which  remains  behind  after  combustion,  and  another  substance.  Phlo- 
giston, possessing  actual  levity.  When  the  body  bums,  this  phlogiston 
escapes,  and  combines  with  the  oxygen  gas  or  dephlogisticated  air,  pro- 
ducing nitrogen  gas  or  phlogisticated  air,  less  both  in  weight  and  volume 
than  the  oxygen.  In  tne  combustion  of  bodies  in  pure  oxygen  gas,  no 
nitrogen  remains  behind. 

2.  Kirwan  :  Combustible  bodies  consist  of  a  substratum  and  phlogis- 
ton, which  latter  is  identical  with  inflammable  air  (hydrogen  gas).  In 
the  act  of  combustion,  the  phlogiston  combines  with  the  oxygen  gas,  from 
which  it  drives  out  the  fire,  and  forms  carbonic  acid,-^r,  at  higher  tem- 
peratures, water.  These  products  are  sometimes  set  free;  sometimes 
they  combine  with  the  substratum,  and  thus  produce  the  various  kinds  of 
burnt  bodies.     This  theory  is  directly  contradicted  by  £Eu;ts. 

3.  Van  Mons :  Combustible  bodies  consist  of  a  substratum  and 
hydrogen.  In  combustion,  the  hydrogen  combines  with  the  oxygen, 
forming  water ;  and  the  water,  uniting  with  the  substratum,  produces  the 
burnt  body :  so  that  the  combustible  is  substratum  -H  hydrogen  ;  the 
burnt  body,  substratum -{- water,  or  combustible -{-oxygen. 

4.  Scheele  :  The  phlogiston  of  combustible  bodies  has  but  little  weight. 
Oxygen  gas  or  fire-gas  consists  of  a  saline  matter  having  but  little  weight, 
together  with  water  and  a  small  quantity  of  phlogiston.  In  the  act  of 
combustion,  the  phlogiston  of  the  combustible  Dody  combines  in  various 
proportions  with  the  saline  matter  of  the  fire-gas,  producing  light  and  heat ; 
and  the  water  of  the  fire-gas  is  transferred  to  the  substratum  of  the  com- 
bustible body.  But  the  burnt  body  weighs  exactly  lu  much  as  the  com- 
bustible body  consumed  and  the  oxyeen  taken  together. 

5.  Richter  :  The  imponderable  phlogiston  of  combustible  bodies  enters 
into  combination  with  the  heat  of  fluidity  of  the  oxygen  gas,  and  produces 
light,  while  the  ponderable  port  of  the  oxygen  combines  with  the  ponder- 
able part  of  the  combustible  body. 


tS  OXTGBK. 

6.  Q'diiVmg :  Plilogiston  is  identieal  with  light :  and  it  partly  com* 
bines  with  the  principU  of  fire  contained  in  oxygen  gas  (I.,  167)i  and 
forms  heat. 


CompoundB  of  Oxifgen, 

The  act  of  combination  of  oxygen  with  other  bodies  is  called 
Oxygenation  {ComftvMion) ;  also  Acidification,  when  the  resulting  com* 
pound  is  of  an  acid  nature ;  Oxidatinn,  in  the  contrary  case.  The 
oxygen  is  the  Oxygenizing  hody  {Suppoiter  of  Combustion))  also  accx>rding 
to  circumstances — the  Acidifying  or  the  Oxidizing  body.  The  body 
which  combines  with  it  is  the  Oxygenizabie  {combustible)  body  ;  also  the 
Acidijiable  or  Oxidable  body,  as  the  case  may  be.  The  new  compound  is 
the  Oxygenized  (burnt)  body ;  the  Acidified  body  in  the  one  case,  the 
Oxidized  or  Oxidated  body  in  the  other.  The  separation  of  oxygen  from 
another  body  is  called  Deoxygenation,  Deacidification,  Deoxidation^  Re- 
duct  on,  or  RentorcUion* 

The  combination  of  oxygen  with  other  bodies  takes  place  according 
\jb  the  following  atomic  proportions : 


2  :  1 

1    :   1 

1   :  2 

1    !   3 

1  t  4 

1  :  5 

1  J  7 

Cs«0 

HO 

co« 

CrO« 

NO* 

PO» 

Clot 

2  :  3 

2  :  9 

3  :  4 

8  1  5 

4  :  5 

Fe«Q» 

8<0« 

MniO* 

S»0» 

6*0» 

Most  substances  are  capable  of  uniting  with  oxygen  in  more  than 
one  proportion  ;  they  have  several  Degrees  of  Oxidation. 

Oxygen  forms  about  1 36  inorganic  compounds :  they  are  as  follows : 

1.  Of  acid  nature:  Oxyqen-acidi^y  Oxacids,  These  bodies  exhibit 
the  properties  of  acids  (p.  3)  in  very  different  degrees.  When  the 
same  radical  forms  several  acids  with  different  quantities  of  oxygen,  that 
which  ccmtains  the  largest  quantity  of  oxygen  is  invariably  the  strongest 
acid.  Acids  are  named  by  affixiug  the  terminations  ic  and  oi/«*  to  the 
name  of  the  radical,  sometimes  immediately,  sometimes  after  removing 
the  last  syllable.  When  a  body  forms  but  one  acid  with  oxygen,  the 
name  of  that  acid  ends  in  ic :  tnus  carbon  forms  carbon-ic  acid  :  when 
two  acids  are  formed,  the  one  which  contains  the  larger  quantity  of 
oxygen  is  distinguished  by  the  termination  ic,  the  other  by  the  ter- 
mination Otis  :  e.  g.  SIO*  =  antimonious  acid  ;  SbO*=  antimonic  acid. 
When  more  than  two  acids  are  formed,  the  two  most  important  are 
designated  in  the  manner  just  described  :  e.  g.  SO*  =  sulphurous  acid, 
SO^  =  sulphuric  acid)  and  the  others  are  further  distinguished  by  the 
prefixes  f/ypo  for  the  lower  degrees  of  oxidation,  Hyper  lor  the  higher  : 
examples  will  bo  seen  in  the  following  paragraphs.  The  combination 
of  oxygen-acids  with  salifiable  bases  produces  the  Oxygen-salts  or  Oxi- 
sdlts  (p.  5). 

The  Oxyffen-acids  are  divided  into  : 

a.  Non'metalli-  Oxygen-acids:  Carbonic  acid,  CO*  ; — boracic  acid, BO': 
— hypophosphorous  acid,  PO.— phosphorous  acid,  PO',— phosphoric  acia 

*  This  and  the  following  paragraphs  reUtiing  to  the  nomenclature  of  ozygen-oom* 
pounds  are  not  translations  of  the  corresponding  paragnphs  in  the  original,  bat  contain 
an  ^lanatlon  of  the  English  nomendatnre  given  in  the  same  ord«r  as  Uiat  in  whish 
Hie  aathor  describes  the  German  nomendatore.     [W.] 


COMPOUNDS  OF  OXYGEN.  89 

PO' ; — hjpoeulphuroQs  aeid,  SO, — sulphurous  aoid,  SO', — sulpburic  acid, 
60*, — ^pentatliionio  aoid,  S^O^— tetrathionic  acid,  S^O^ — tritbionic  acid, 
S*0*, — hyposulphuric  aoid,S'0^; — seletiious  acid,  SeO', — selenic  acid,  SeO'j 
iodic  acid,  IO^-^periodic  or  by  per  iodic  acid,  10^  j — brfmiio  acid,  BrO'; 
— hypochlorous  acid,  CIO, —  chlorous  acid,  C10^-*chloric  acid,  GIO', 
—perchloric  or  byperoblorio  acid,  CIO' ; — ^nitrous  acid,  NO*, — hypo- 
nitric  acid,   NO^ — uitrio  acid,  N0\  , 

b.  Metallic  Oxypen-^^idi :  (Silicic  acid,  SiO')  ;*— (titanic  acid; 
TiO»)  ;— tautalous  acid,  TaO',— tantalio  acid  TaO» ;  niobic  acid,  NbO*(t); 
— pelopic  acid,  PeO*(?); — ^tungstic  acid,  WO*; — molybdio  acid,  MoO' ; — 
▼anadio  acid,  VO*  ;— chromic  acid  CrO*  ; — manganic  acid  MuO*, — 
permanganic  or  bjrpermanganio  acid,  Mn*0* ; — arsenious  acid,  AsO'; — 
arsenic  acid,  AsO^ ; — antimoni«ius  acid,  SbO', — antimonio  acid,  SbO^ ; — 
^tellurous  acid,  TeO'), --tell uric  acid,  TeO'  ;— ^stannic  acid,  SnO') ; — 
ferric  acid,  FeO*  ;— cobaltic  acid,  CoO'(?)  ;— ^rutheuio  acid,  RuO*; — 
and  osmic  acid,  OsO^. 

2.  Compounds  not  of  acid  nature  :  Oxide$.  When  a  metal,  by  com- 
bining with  different  quantities  of  oxygen,  forms  two  oxides  belonging 
to  the  same  class,  these  compounds  are  sometimes  distinguished  in  the 
same  way  as  acids,  vie.  by  adjectives  ending  in  ou$  and  is ;  but  more 
frequently  they  are  named  according  to  the  relative  numbers  of  atoms 
of  metal  and  oxygen  which  they  contain  :  thus,  one  atom  of  metal  with 
one  atom  of  oxygen  forms  a  Protoxide-,  1  At  metal  with  8  At.  oxygen, 
a  Bi-oxide,  Binoxide  or  Deutoxide;  1  At  metal  with  3  At  oxygen,  a 
Teroxide;  1  At  metal  with  4  at  oxygen ;  a  Quadroxide;  2  At  metal 
with  8  At  oxygen,  a  Seiquiroxide ;  2  At.  metal  with  1  At  oxygen,  a 
Di-oxide  or  Dinoxide, 

Oxides  may  be  divided  into  three  classes,  as  follows : — • 

a.  Salifiahle  Oxidee:  Oxides  having  the  character  of  salifiable  bases. 
These  are : 

a.  Alkalis  (p.  4).  Potnssa  or  potash,  KO; — soda,  NaO; — lithia, 
LO; — baryta,  BaO; — strontia,  SrO;— lime,  CaO;— oxide  of  ammonium, 
NHH),  may  also  be  placed  in  this  gronp. 

p.  Earths  (p.  4).  Magnesia,  MgO;-^lanthana  or  protoxide  of 
lanthanum,  LaO; — oxide  of  didymium,  DiO(?);*— -protoxide  of  cerium  or 
cerous  oxide,  CeO, — sesquioxide  of  cerium  or  cerio  oxide,  Ce'O'; — 
yttria,  YO; — glucina,  GO; — alumina,  AlW;— thorina,  ThO; — xirconia, 
ZrO;— (silica,  SiO»). 

y,  Basic  Heavy  Metallic  Oxides:  Protoxide  of  titanium  or  titanous 
oxiae,  TeO  (?),— (bi-oxide  of  titanium  or  titanic  oxide,  TiO*); — protoxide 
of  molybdenum  or  molybdous  oxide,  MoO, — ^bi-oxide  of  molybaenum  or 
molybJlic  oxide,  MoO';— bi-oxide  of  vanadium  or  vanadic  oxide, 
VO*; — ^protoxide  of  chromium  or  chromous  oxide,  CrO, — sesqui-oxide 
of  chromium  or  chromic  oxide,  Cr'O'; — protoxide  of  uranium  or 
-uranons  oxide,  UO; — sesqui-oxide  of  uranium  or  uraaic  oxide,  U*0*; 
-^-protoxide  of  manganese  or  manganous  oxide,  MnO,— sesqui-oxide 
of  manganese  or  manganic  oxide,  MnK)*; — teroxide  of  antimony  or 
antimonic  oxide,  SbO^; — (bi-oxide  of  tellurium  or  telluric  oxide,  TeO*); 
— sesqui-oxide  of  bismuth,  Bi'O';— oxide  of  zinc,  ZnO;— oxide  of  cadmium, 
CdO; — protoxide  of  tin  or  stannous  oxide,  SnO, — (bi-oxide  of  tin  or  stannic 
oxide,  SnO');— protoxide  of  lead  or  plumbic  oxide,  PbO; — protoxide  of 

*  Adds  and  bases  whose  names  are  enclosed  within  brackets  are  amphoteric  bodies, 
that  is  to  say,  they  have  a  very  weak  add,  and  likewise  a  very  feeble  banc  character,  and 
wiU,  therefore,  be  again  mentioned  among  the  salifiable  bases. 


40  OXYGEN. 

iron  or  ferrous  oxide,  FeO, — sesqui-oxide  of  iron  or  ferric  oxide,  FeK)*; 
— protoxide  of  cobalt  or  cobaltous  oxide,  CoO, — sesqui-oxide  of  cobalt  or 
cobaltic  oxide,  Co*0'; — protoxide  of  nickel,  NiO;— di-oxide  of  cop]«er 
or  cuprous  oxide,  Cu*0, — ^protoxide  of  copper  or  cnpric  oxide,  CuO; — 
di-oxide  of  mercury  or  mercnrious  oxide,  Hg'O, — protoxide  of  mercury 
or  mercuric  oxide,  H^O; — di-oxide  of  silver  or  argentons  oxide,  Ag'O,  (lj, 
— protoxide  of  silver  or  argentic  oxide,  AeO; — ^ter-oxide  of  gold  or  auric 
oxide,  AuO'; — protoxide  of  platinum  or  platinous  oxide,  PtO, — bi-oxide 
of  platinum  or  platinic  oxide,  PtO'; — ^protoxide  of  palladium  or  palladions 
oxide,  PdO, — bi-oxide  of  palladium  or  palladic  oxide,  PdO*; — ^protoxide 
of  rhodium  or  rfaodious  oxide,  RO, — sesqui-oxide  of  rhodium  or  rhodic 
oxide,  R'O'; — ^protoxide  of  iridium  or  iridious  oxide,  IrO, — sesqui-oxide  of 
iridium,  Ir'O'', — ^bi-oxide  of  iridium  or  iridic  oxide,  IrO', — ^ter-oxide  of 
iridium,  IrO^; — ^protoxide  of  ruthenium  or  ruthenious  oxide,  HuO, — ses- 

Sui-oxide  of  ruthenium,Ru'0', — bi-oxide  of  ruthenium  or  ruthenic  oxide, 
,u0'; — protoxide  of  osmium  or  osmious  oxide,  OsO, — sesqui-oxide  of 
O8raium,08'0', — ^bi-oxide  of  osmium  or  osmic  oxide,  OsO', — ter-oxide  of 
osmium,  OsO'. 

b.  Oxides  which  are  either  wholly  incapable  of  combining  with  other 
bodies,  or  form  a  few  very  unstable  compounds,  and  possess  neither  acid 
nor  basic  properties,  because  they  contain  too  little  oxygen :  by  taking  up 
more  oxygen,  they  are  converted  either  into  acids  or  bases. — Suboxides, 

a.  ^' on-metallic  Suboxides:  These,  by  taking  up  more  oxygen,  are  con- 
verted into  acids :  carbonic  oxide,  CO ;— -oxide  of  phosphorus  or  phos- 
phoric oxide,  PO;— oxide  of  selenium  or  selenic  oxide,  SeO  (?); — 
protoxide  of  nitrogen  or  nitrous  oxide,  NO; — ^bi-oxide  of  nitrogen  or 
nitric  oxide,  NO'. 

j8.  Metallic  Suboxides. — These,  by  addition  of  oxyg>en,  are  rarely  con- 
verted into  acids,  more  frequently  into  bases.  Those  with  a  note  of  inter- 
rogation after  them  are  doubtful,  probably  mere  mixtures  of  metal  with  a 
higher  oxide:  suboxide  of  potassium  (1), — suboxide  of  sodium  (?); — 
tungstous  suboxide,  WO*, — ^tungstic  suboxide,  WO'; — suboxide  of  vana- 
dium, VO; — suboxide  of  arsenic; — suboxide  of  antimony  (?); — suboxide  of 
bismuth  (9); — aureus  suboxide,  AuO, — auric  suboxide. 

c.  Oxides  which  form  scarcely  any  compounds,  because  they  contain 
too  much  oxygen  to  form  bases,  and  too  little  to  form  acids.  By  taking 
up  a  larger  quantity  of  oxygen,  some  of  them  are  converted  into  acids. 
Peroxides  or  HyperoxidesJ* 

a.  Non-metallic  Peroxide :  Peroxide  of  hydrogen,  (sometimes  also 
deroxide  of  nitrogen,  NO*). 

/3.  Metallic  Peroxides:  Peroxide  of  potassium;^-of  sodium;— of  lithium; 
—of  barium,  BaO';— of  strontium;— -of  calcium; — of  manganese,  MnO*; — 
of  bismuth; — plumbous  peroxide  (red  lead),  Pb'O*, — ^plumbic  peroxide, 
PbO'; — ^peroxide  of  nickel,  Ni'O'; — peroxide  of  silver. 

d.  Water  stands  apart  from  all  these  oxides.  In  some  of  its  com- 
pounds, it  plays  the  part  of  an  acid ;  in  others,  that  of  a  base :  but  it  can- 
not be  said  to  belong  to  either  class  in  particular. 

*  The  term  Peroxide  is  often  used  in  English  nomenclature  to  denote  merely  the 
highest  degree  of  oxidation  of  a  metal,  irrespectiTe  of  basic  or  nod-basic  properties;  but 
it  would  be  as  well  if  this  use  of  it  were  abandoned.     [  W.] 


HYDROGBN.  41 

Chapter  II. 

HYDROGEN. 


Compotitian  of  Water, 

Scheele.     CrelL  Ann.  1785,  2,  229,  and  291. 

Cavendish.     Crell,  Ann.  1765,  1,  324. 

Watt.     CreU.  Ann.  1788,  1,  23,  and  136. 

Meusnier  &  Lavoisier.     CreU.  Ann.  1788,  1,  354,  441,  and  528. 

Lavoisier.    System  der-antiphloffUtischen  Chemie;  libera,  von  Hermbst. 

S.  123. 
■  Apparent  conversion  of  Water  into  Earth.  CreU.  Chem.  J, 

3,  151. 
Berzelius  &  Dulong.    Ann.  Chim.  Phye.  15,  386. 
Dumas.     Comptes  rendua.  14,  537. 

Oxy-hydrogen  Blowpipe. 

Hare.    Ann.  Chim.  45,  113;  abstr.  GiU>.  55,  43 

FhU.  Mag.  50, 106 ;  also  Scker.  Ann.  3,  250. 

Brooke.    Ann.  FhU.  7,  367. 

Newman.  Quart.  J.  of  Se.  1,  65;  2,  379;  also  Schw.  18,  225,  and 
333;  also  Gilh.  55,  1.  and  7. 

Clarke.  Quart.  J.  of  Se.  2,  104;  also  Sekw.  18,  228.— ^nn.  PhU.  8, 
313,  and  357;  9,  89,  162,  194,  and  326;  10,  133,  and 
373;  17,  419;  partly  also  in  Sekw.  21,  382;  also  Qilb. 
62,  247,  and  339;  also  Seker.  Ann.  3,  221. 

Faraday.     Quart.  J.  of  Se.  2,  461;  also  Sohw.  18,  337. 

Larapadius.    Schw.  19,  319. 

Ridolfi.    Schw.  20,  218. 

Pfaff.    Schw.  22,  385. 

Gaj-Lnssac    Ann.  Chim.  Phys.  14,  302. 

Chodkiewioz.    Scher.  Ann.  3,  248. 

Cooper.     Scher.  Ann.  5,  245. 

Hiibenthal.     Scher.  Ann.  244. 

Parrot.  Scher.  Ann.  3,  239;  7,  280. — Pander  BeUr.  tur  Naturgeach. 
1,50. 

Skidmore.    SiU.  Am.  J.  5,  347;  also  Sekw.  39,  359. 

Holme,  Edwards,  Beale,  Cbirke,  Gray,  Booth,  Osbrey,  Barohard,  and 
others.  Ann.  PhU.  8,  470;  9, 167,  252,  253, 402,  481, 
and  483;  10,  66,  67,  and  366;  abstr.  Gilb.  62,  270.— 
Watt  Ann.  PhU.  11,  386.— Leeson.  Ann.  PhU.  14, 
234. 

Schmidt.     GUb.  66,  84. 

Herrmann  &  Bischof.    Schw.  56,  123. 

Rntter.    PhU., Mag.  J.  I,  470. 

Hemming.    PhU.  Mag.  J.  1,  32. 

Bischof.    J.  pr.  Chem.  14,  129. 

Daniell.    PhU.  Mag.  J.  2,  57;  abstr.  Pogg.  25,  635. 

Excitement  of  Cmbuition  by  PloHnumf-^B^  the   papers   cited  on 
page  19. 


4f  HYDROGEN. 

WcUer  offfydratian  and  Crystallization, 

BeTzelius.     GUh.  40,  246. 

Graham.    PhU,  Mag.  J.  6, 327;  also  Pogg,  38, 123;  also  J.pr.  Chem. 

5,  90  —Ann.  Pharm.  29,  i.— Elements,  169. 
Fremy.    J.  Pharm.  11,  169;    abstr.   Ann.  Pharm.  64,  223;  also 

Q.  Joum.  Chem.  Soc.  1,  380. 

Ahsorption  of  Gases  by  Water. 

Priestley.  Americ.  Trans.  5,  21;  Crell.  Ann.  1798,  1,40;  and  in  Exp. 
and  Obs.  on  Air.  2,  263.— Cavendish.  Phil.  Trans.  5^,  161.— 
Berger.  J.  Phys.  57,  5;  also  Gilb.  20,  168.  Dalton.  Manchester 
Memoirs,  See.  Ser.  1,  284:  5,  11;  N.  Syst.  1,219;  Attn.  PhU.  7,  215; 
also  Schw.  17, 160.— W.  Henry.  Phil.  Trans  93,  29,  and  274;  partly 
also  in  Gilb.  20,  147. — Von  Humboldt  and  Gay  Lussac.  J.  Phys  60, 
129;  also  Gilb.  20,  129.— Berthnllet.  Ann.  Chxm.  53,  239;  also  GiUb. 
20,  166— De  Marty.  Ann.  Chim.  61,  271;  also  Gilb.  28,  417;  also 
JV.  Geld.  4,  141. — Carradori.  Annali  di  Storia  naturale  di  Pavia,  5, 
12,  and  15;  J.  Phys.  62,  473;  also  Gilb.  28,  413:  Brugn.  Giom.  6, 
333.— Theod.  de  Saussare.  i5i&/.  Crit.;  also  Gilb.  47, 163.— Thomson, 
Systime  de  Chimie  trad,  par  Riffatdt  sur  la  5"*  edition,  3,  61.— Gra- 
ham, Ann.  Phil.  28,  69. — Baumgartner.  Zeitsekr.  Phys.  Math.  8,  9. 

Aqueous  Solutions. 

Oay-Lassao.  Ann.  Chim.  82,  171;  also  Gilb.  42, 117.  Ann.  Chxm.  Phys, 
11,  296;  also  Schw.  27,  364;  also  N.  Tr.  4,  2,  296.— Karsten, 
Sehriften  d.  Serl.  Akad.  1841.— Persoz,  Ann.  Chim.  Phys.  68,  273; 
also  Ann.  Pharm.  33,  80. — Kopp,  Ann.  Pharm.  34,  260. 

Peroxide  of  Hydrogen, 
Th^nard.  Ann.  Chim.  Phys.  8,  306;  9,  51,  94,  314,  and  441;  10, 114,  and 
335;  11,  85,  208;  50,  80;  partly  also  in  Schw.  24,  257;  65,  439; 
also  N.  Tr.  3,  1,  60,  72,  and  80;  3,  2,  373,  and  378;  4,  2,  37,  and 
40;  also  GUb.  64, 1. — ^Compare  also  Th^nard,  TraiU  de  Chimie,  ed.  4, 
t.  2,  41. 

Basis  of  Water,  Hydrogkne^  llydrogenium,  Wasserstoff ;  and  in  the 
state  of  gas  :  Ht/drogen  gas.  Inflammable  Air,  Gas  hydrogine,  Gas 
hydrogenium,  Wasserstof-gas. 

History.  Water  was  lon^i^  regarded  as  an  elementary  substance.  It 
was  for  some  tinie  supposed  that  by  repeated  distillation  it  could  be 
oonyerted  into  an  earth ;  till  Lavoisier  showed  that  the  earthy  deposit 
in  the  tflass  distilling  vessels  proceeded  from  the  glass  itself.  The  in- 
flammable air  which  is  evolved  during  the  solution  of  certain  metals  in 
dilute  acids  had  been  known  for  some  time ;  and  in  1781,  Cavendish 
and  Watt  first  showed  that  in  the  combination  of  this  eas  with  oxygen, 
which  takes  place  when  it  is  burnt,  water  is  produced.  Subsequently, 
Lavoisier  decomposed  water  into  its  elements.  Von  Humboldt  and  Gay- 
Lussac  showed  that  one  volume  of  oxygen  gaa  combines  with  exactly 
two  volumes  of  hydrogen  gas  to  form  water ;  whereas  Laroisier  and 
Meusnier  had  found  the  ratio  to  be  12:  23;  Fourcroy,  Vauquelin  and 
Seguin,  100:  205;  and  NiokoUon  and  Carliale,  72  :  148.— In  1818, 
Th^nard  discovered  the  peroxide  of  hydrogen. 


RTDROGBN.  48 

Sources,  Hydrogen  is  nerer  found  in  the  free  state^  The  compound 
which  contains  it  in  the  greatest  abundance  is  water,  of  which  it  forms 
one-ninth.  It  occurs  in  smaller  quanties  in  combination  with  phosphorus, 
sulphur,  iodine,  bromine,  carbon,  and  nitroffen ;  and  finally,  in  almost 
all  organic  compounds.  -  The  gas  which  exists  in  a  highly  compressed 
state  in  the  decrepitating  rock-salt  of  Wieliczka,  and  is  set  free  with 
a  decrepitating  noise  when  the  salt  is  dissolved  in  water,  appears  to 
be  a  mixture  of  hydrogen,  carbonic  oxide,  and  marsh-gas.  (H.  Rose, 
Pogg.  48,  Z5B\  oomp.  Dumas,  Ann.  Chim.  Phy;  48,  316  ;  also  Fogg,  18, 
601 ;  also  Sckw.  69,  486). 

Preparation.     Always  by  decomposition  of  water. 

1.  It  is  obtained  in  the  state  of  greatest  purity  by  electric  action  : 
(a  )  Berzelins  conducts  two  brass  wires  connected  with  the  poles  of  a 
▼oltaic  battery,  into  water  the  conducting  power  of  which  has  been  in- 
creased by  the  addition  of  a  little  common  salt. — (b.)  A  platinum  wire 
is  sealed  into  a  glass  tube,  filled  with  water— to  which  a  small  quantity 
of  some  salt  is  aidded  to  make  it  a  better  conductor, — and  inverted  in  a 
glass  filled  with  the  same  liquid,  into  which  the  positive  pole  of  a  voltaic 
battery  is  made  to  dip,  while  the  negative  pole  is  connected  with  the 
wire  fused  into  the  tube. — (c.)  Fuchs  {Schw.  15,  494)  inverts  a  platinum 
crucible  in  dilute  hydrochloric  acid,  and  places  a  zinc  plate  in  connexion 
with  its  base  :  a  considerable  quantity  of  hydrogen  gas  tben  collects  in 
the  crucible. — (d.)  Dbbereiner  (GiW,  6S,  55)  puts  a  quantity  of  solution 
of  sal  ammoniac  into  a  tube  closed  with  a  bladder  at  bottom  and  fitted 
with  a  gas-delivery  tube  at  top  ;  dtps  a  platinum  wire  into  the  solution  ; 
immerses  the  whole  in  a  vessel  containing  dilute  sulphuric  acid  and  a 
piece  of  zinc ;  and  coonecte  the  zinc  with  the  platinum  wire. 

2.  Amalgam  of  potassium  is  placed,  together  with  water,  in  a  gas- 
generating  vessel.  The  gas  thus  obtained  is  scentless  ;  but  it  acquires 
the  same  odour  as  that  evolved  by  zinc,  if  a  little  acid  be  added  to  the 
water.   (Berzelins,  J^ehrb.  1,  147.) 

3.  Vapour  of  water  is  passed  over  finely-divided  iron  contained  in  a 

rin-barreJ  beated  to  bright  redness.  Tfae  middle  part  of  the  gun-barrel 
{^pp.  42)  contains  iron  nails  or  wire  (filings  alone  would  st<ip  pp  the 
tube).  When  it  is  red  hot,  the  water  contained  in  the  retort  a  is  made 
to  boil.  The  iron  is  converted  into  Fe'O*,  but  a  great  part  of  the  water 
passes  over  nndecomposed.    (I.,  1 25.) 

4.  Zinc  or  iron  is  dissolved  in  1^  parts  of  oil  of  vitriol  previously 
diluted  with  an  eightfold  quantity  of  water, — or  in  2  parts  of  hydrochloric 
acid  diluted  with  4  parts  of  water.     (Scheme  17.) 

The  gas  obtained  by  the  use  of  zinc  may  contain  the  following  im- 
purities :  1.  Sulphurous  acid,  if  this  acid  were  present  in  the  oil  of  vitriol 
employed. --2.  Nitrous  oxide  or  nitric  oxide  gas,  if  the  oil  of  vitriol 
contains  nitric  oxide,  nitrous  acid,  or  nitric  acid.  *  3.  Carbonic  acid,  found 
by  Donovan  and  also  by  the  author,  with  a  particular  kind  of  zinc,  but 
not  in  any  other  case.— 4.  Hydrosulphuric  acid  gas,  if  the  zinc  ountains 
sulphide  of  zinc,  or  the  oil  of  vitriol  contains  sulphurous  acid,  or  if  fresh 
oil  of  vitriol  be  added  to  the  dilute  acid  already  acting  on  the  zinc  and 
rising  in  temperature,  without  mixing  it  well  with  the  rest  of  the  liquid 
(Fordos  and  Gelis,  •^.  Pharm,  27,  730). — 5.  Phosphuretted  hydrogen  gas, 
if  the  zinc  contains  phosphorus. — 6.  Arseniuretted  hydrogen,  if  the 
vine  oontains  arsenic,  or  the  oil  of  vitriol  is  contaminated  with  arsenious 
atid.--Th«ee  impuritiet  givt  the  gaa  an  nnpleaoaat  odour.    To  obtain  il 


44  HYDROGEN. 

free  from  this  odonr^  it  is  necessarj  to  use  oil  of  vitriol  not  containing 
any  compound  of  oxygen  and  nitrogen,  and  to  pass  the  hydrogen  through 
liquids  which  will  absorb  or  decompose  the  adventitious  gases. — Donovan 
(Ann.  Chim.  Phy%,  2,  375 ;  also  N,  Tr,  1,  2,  295)  removes  the  carbonic 
acid  and  hydrosulphuric  acid  (and  likewise  the  sulphurous  acid)  by 
means  of  aqueous  solution  of  ammonia  (or  potassa),  decomposes  the  phos- 
phide and  arsenide  of  hydrogen,  which  give  rise  to  the  phosphoric  odour 
and  cause  the  gas  to  bum  with  a  green  lame,  by  means  of  fuming  nitric 
acid  (on  the  evaporation  of  which,  phosphoric  and  arsenic  acid  are  ob- 
tained), and  finally  removes  the  nitric  oxide  gas  which  results  from 
decomposition  of  the  nitric  acid,  by  oil  of  vitriol. — Berzelius  {Lekrb. 
1,  1 85)  passes  the  hydrogen  ffsus  through  two  long  tubes,  the  first  con- 
taining linen  saturated  with  solution  of  sal-ammoniac,  which  retains  the 
arseniuretted  hydrogen  (likewise  the  phosphuretted  hydrot^n)  ; — the 
second,  fragments  of  hydrate  of  potassa,  which  takes  up  the  hydrosulphuric 
acid  (aJso  the  sulphurous  and  carbonic  acids).  According  to  Berzelius, 
the  mere  passing  of  the  gas  through  solution  of  potassa  or  through  a  tube 
filled  with  fragments  of  hydrate  of  potassa  renders  it  perfectly  inodorous, 
while  the  potassa  acquires  a  sharp,  repulsive  odour. — Dumas  (Cbmp^  rend, 
1 4,  540)  conducts  the  hydrogen  gas  through  two  U-tubes,  each  about 
three  feet  long,  and  filled  with  broken  glass.  The  glass  in  the  first  tube 
is  moistened  with  solution  of  nitrate  of  lead,  which  removes  the  Iwdro- 
sulphuric  acid  j  that  in  the  second  with  sulphate  of  silver,  by  which  the 
arseniuretted  hydrogen  is  separated*;  then  follows  a  third  U-tube  filled 
with  fragments  of  pumicenstone  saturated  with  strong  solution  of  potassa. 
Finally,  to  render  the  gas  anhydrous,  it  is  passed  through  a  tube  filled 
with  fragments  of  hydrate  of  potassa ;  then  through  another  containing 
oil  of  vitriol  or  anhydrous  phosphoric  acid. 

Hydrogen  gas  obtained  by  means  of  iron  may  contain  the  same  impu- 
rities as  that  obtained  by  the  use  of  zinc.  But  besides  these  it  contains  : 
1.  Ferruretted  hydrogen  gas  {vid.  Iron),  to  be  removed  by  fuming  nitric 
acid  or  solution  of  corrosive  sublimate  (Dupasquier,  Compt,  rend,  14, 
511).  2.  The  yapour  of  an  oily  hydro-carbon,  which  is  produced  in 
greater  abundance  in  proportion  as  the  iron  contains  more  carbon,  and 
communicates  a  peculiar  repulsive  odour  to  the  gas.  This  oil  may  be 
removed  by  passmg  the  gas  through  alcohol,  and  the  alcohol  afterwards 
separated  by  water.     (Berzelius.) 

The  gas  obtained  by  the  use  either  of  zinc  or  of  iron  may  be  deprived 
of  all  odour  in  four  and  twenty  hours,  by  means  of  moistened  charcoal 
powder.     (Dobereiner,  Sckw,  3,  377.) 

5.  By  dissolving  zinc  in  contact  with  iron,  in  caustic  potassa.  The 
gas  thus  obtained  is  perfectly  inodaroiu,    (Runge,  Pogg,  16,  130.) 

In  whatever  manner  the  gas  may  be  prepared,  it  always,  according  to 
Bischof  (Kustn,  Arch.  1,  179),  contains  a  small  quantity  of  atmospheric 
air, — ^the  chief  cause  of  which  impurity  is,  most  probably,  that  the  liquids 
used  in  its  preparation  contain  air  in  solution.  The  nitrogen  cannot  be 
removed ;  but,  according  to  Dobereiner  (^Schw.  42,  62),  the  oxygen  may 
be  separated  by  leaving  the  gas  for  a  while  in  contact  with  spongy  plati- 
num, which  causes  the  oxygen  to  combine  with  a  portion  of  the  hydrogen 
and  jform  water. 

Properties.  Colourless  gas.— Sp.  gr.  (I.,  279).  According  to  the  latest 
determination  b^  Dumas  &  Boussingault,  it  is  between  0*691  and  0*695. — 
Hydrogen  gas  is  therefore  14^  times  lighter  than  air ;  hence  it  may  be 


WATXr.  45 

ased  for  inflating  air-balloons.  Soap-bnbblee  filled  with  it  rise  rapidly  ini 
the  air.  It  escapes  rapidly  out  of  vessels  with  their  mouths  turned 
upwards^  but  slowly  out  of  those  which  have  their  mouths  placed  in  the 
reverse  position.  [For  its  refracting  power,  see  Vol.  I.,  p.  05.]  Very 
inflammable,  but  does  not  support  the  combustion  of  other  bodies.  Ino* 
dorous,  in  the  pure  state  ;  but  as  commonly  obtained,  it  has  a  disagreeable 
smell.  Small  animals  introduced  into  this  gas  die  instantly.  In  man,  the 
pure  gas  excites,  after  two  inspirations,  disagreeable  sensations  and  loss  of 
muscular  power ;  when  mixed  with  air,  it  majr  be  breathed  for  a  longer 
time  (Scheele,  Fontana,  H.  Dav^).  Its  injurious  action  is  merely  nega- 
tive ;  that  is  to  say,  so  long  as  it  is  inhaled,  oxygen  gas,  which  is  essen- 
tial to  life,  is  prevented  from  entering  the  lungs.  The  violent  symptoms 
experienced  by  Cardone  (Q%taH.  J.  of  Se.  20,  393)  must  have  proceeded 
from  impurities  in  the  gas. 

Combinations.  The  combination  of  hydrogen  with  other  bodies  is  not 
attended  with  development  of  light  and  heat,  excepting  when  it  combines 
with  oxygen  and  chlorine,  that  is  to  say,  with  the  most  highly  electro- 
negative of  all  known  substances. 

,  Hydrogen  and  Oxtoen. 

A.    Water.    HO. 

Sources,  Difl^used  through  the  atmosphere  in  the  form  of  vapour; 
also  as  rain,  snow,  spring-water,  river -water,  sea-water ;  as  water  of  crys- 
tallisation in  many  minerals ;  as  a  constituent  of  organic  bodies. 

Formation,  The  ponderable  matter  contained  in  one  volume  of  oxy- 
gen gas  is  exactly  sufficient  to  convert  into  water  the  ponderable  matter 
in  2  volumes  of  hydrogen  gas.  The  two  gases  may  be  mixed  at  ordinary 
temperatures,  so  as  to  produce  detonating  gas;  but  the  oxygen  and  hydro- 
gen will  not,  under  these  circumstances,  combine  together  in  the  form  of 
water.  The  combination  may  be  brought  about,  slowly  or  rapidly,  in  the 
following  ways : — 1.  By  elevation  of  temperature. — 2.  By  the  electric 
spark. — 3.  By  sudden  pressure. — 4.  By  platinum  and  other  solid  bodies. 
— 5.  By  contact  with  organic  bodies  in  a  state  of  slow  oombnstion.-*6. 
By  contact  with  water  (?). 

1'.  Not  only  the  flame  of  a  burning  body,  but  likewise  the  heat  of  a 
red-hot  iron  wire,  or  a  coal,  hot  enough  to  exhibit  a  visible  glow  by  day- 
light, is  sufficient  to  induce  the  rapid  combination. 

2'.  The  smallest  possible  electric  spark  is  sufficient  to  cause  the  mix- 
ture to  take  fire. — Vavendish's  Apparatus.  The  electric  spark  excites 
combustion  only  in  those  parts  of  the  mixture  which  it  actually  touches ; 
but  the  heat  excited  by  this  combustion  raises  the  temperature  of  the  con- 
tiguous particles,  and  thus  the  combustion  is  propafifated  through  the  whole 
mass.  But  when  the  detonating  gas  is  mixed  with  other  gases  which  oool 
it  down  (p.  34^,  combination  is  limited  to  the  small  quantities  of  gas  on 
which  the  spark  exerts  its  direct  action.  Hence,  1  volume  of  detonating 
gas  no  longer  takes  fire  by  the  influence  of  the  spark  when  it  is  mixed 
with  ^  a  volume  of  olefiant  gas,  1  volume  of  marsh -gas,  2  volumes  of 
hydrochloric  acid,  8  of  hydrogen,  9  of  oxvgen,  or  II  of  nitrous  oxide  gas 
(H.  Davy) ;  similarly,  when  it  is  mixed  with  1^  volume  of  cyanogen, 
2  volumes  of  ammoniacal  gas,  3  of  carbonic  acid,  4  of  carbonic  oxide,  or  6 
of  nitrogen  (W.  Henry,  Ann,  PhU,  25,  426).    One  volume  of  detonating 


46  HYDIOOBN. 

gas  mixed  with  ^  of  a  rolvm^  of  ^^rbonio  ozid^  may  be  exploded  bj  tlie 
•park  of  a  powerfol  Leydeo  jar,  but  not  when  it  i«  mixed  with  4  &  Tolnme 
of  the  same  gas.  Similarly,  of  the  following  pairs  of  iiumbers,  the  first 
denotes  the  number  of  volumes,  which,  when  added  to  1  volume  of  detor 
natinii?  gas,  still  allows  the  explosion  to  take  pleuse  ;  the  seeond,  the  nunw 
ber  of  volumes  which  prevents  it.  Hydrosulphuricaoid,  ^  and  ^  ;  oleiiant 
gas,  ^  and  1 ;  ammoniacal  gas,  ^  and  1 ;  sulphurous  acid,  1  and  2  ;  car* 
bonie  acid,  2  and  3  ;  carWiic  oxide  or  hydrochloric  aeid,  3  and  4 ; 
hydrogen  or  nitrous  oxide,  7  and  9  ;  air,  10  and  12  ;  oxygen,  12  and  14. 
The  abstraction  of  heat  cannot  be  the  only  cause  which  prevents  the  ex- 
plosion ;  since  the  quantities  required  to  prevent  it  are  not  in  the  inverse 
ratios  of  the  specific  beats  of  the  gases.  (Turner.     £d.  Phil.  J.  12,  31 1.) 

o'.  On  rapidly  compressing  a  quantity  of  detonating  gas  in  an  iron 
tube,  combination  took  place,  and  the  tube  burst  (Biot.  A.  Gekl.  6,  95  ; 
also  GilO.  20,  09).  If,  on  the  other  hand,  detonating  gas  contained  in  a 
tube  sealed  at  the  top  and  closed  with  mercury  at  the  bottom,  be  sunk  in 
the  sea  to  the  depth  of  540  metres  (295  fathoms),  where  the  gaseoits 
mixture  is  subjected  to  a  pressure  of  50  atmospheres,  no  combination  takes 
place  (Dc  la  Roche,  Scliw.  I,  172). — If  two  platinum  wires  are  sealed 
into  a  strong  glass  tube,  the  tube  filled  with  water  acidulated  with  sulphu- 
ric acid,  a  manometer  introduced  to  determine  the  pressure,  then  the  tube 
sealed  at  the  other  end,  an<l  the  water  decomposed  by  the  electric  cusrent, 
the  detonating  gas  at  length  attains  a  tension  of  150  atmospheres,  and  is 
therefore  compressed  into  ytz  ^*^  ^^  ordinary  bulk, — and  yet  no  recombi- 
nation takes  place.   (Degen,  Poffg  38,  454.) 

4'.  Platinum. — If  a  platinum  wire  wound  into  a  spiral  form,  and 
placed  at  the  opening  of  a  glass  tabe  from  which  hydrogen  gas  is  flowing, 
be  gently  heated,  it  will  become  red-hot  and  set  the  hydrogen  on  fire. 
On  blowing  out  the  flame  so  that  tlie  wire  may  o(»ol  down  below  redness,  it 
soon  becomes  red  hot  again,  and  rekindles  the  gas  with  a  slight  detonation. 
(Palladium  acts  in  a  similar  manner,  but  less  strongly  ;  whereas  wires  of 
gold,  silver,  copper,  iron,  and  sine  produce  no  effect  of  the  kind.)  H.  L'avy. 

Fiue  plaiioum  wire  wouud  into  a  spiral  sets  detonating  gas  on  fire  at 
a  temperature  even  as  low  as  50^  or  51^  (Erman).  When  a  wire  of  this 
description  has  been  used  io  the  lamp  without  flame  (vid.  Alcohol),  it  is 
found  to  be  corroded  at  the  part  where  it  was  red  hoi,  appearing  dull  and 
of  a  blackish  grey,  and  consisting  of  a  net- work  of  thin  fibres  ;  such  a  wti^ 
placed  in  a  mixture  of  air  and  hydrogen  gas  at  temperatures  iietween  ;37'' 
aad  $0''  (99^  and  122°  F.)  becomes  red  hot  at  die  corroded  part. 
(Pleischl.) — Platinum  wire  Vt  ^^  *  millimetre  in  thickness,  and  wound 
into  a  spiral  of  100  coils,  requires,  when  new,  a  temperature  of  300**  to 
make  it  exert  the  peculiar  water-forming  action ;  but  after  several  igni- 
tions, it  acts  aA  low  as  50°  or  €0°.  After  being  immersed  in  nitric  acid, 
either  hot  or  cold,  and  then  dried  at  200^,  it  acts  even  at  the  ordinary 
temperature  of  the  air,  and  becomes  red-hot  when  a  sufficiently  strong 
enrrent  of  mixed  air  and  hydrogen  is  directed  upon  it.  Sulphuric  acid 
exerts  an  action  similar  to  that  of  nitric  acid,  but  weaker;  hydrochloric 
acid,  still  weaker.  This  property  imparted  by  acids  is  retained  by  the 
platianm  wire  for  a  few  hours  only,  when  it  is  exposed  to  the  air  ;  bi^t  if 
the  wire  be  kept  in  a  vessel,  no  matter  of  what  description,  it  retains  the 
same  property  for  upwards  of  24  honrs.  The  wire  loses  this  property  if 
it  be  insulated  by  inserting  it  into  a  stick  of  sealing-wax,  and  immersing 
it  for  ^y^  minutes  in  inflated  mercury,  or  if  it  be  exposed  for  the  same 

I  to  a  cnireoi  of  dry  air,  or  of  dry  oxygen,  hydrogen,  or  carbonic  acid. 


FORMAnON  or  WATER.  47 

AnuDOiiia^  pota«8a»  or  foda,  on  the  oomtmry,  does  not  deprire  the  wire  of 
ite  peculiar  power.    (Dulong  &  Th^nard.) 

TUtinam  filinp  of  medium  size  exhibit,  when  auite  freshly  prepared, 
the  power  of  caosmg  the  formation  of  water,  and  become  heated,  thongh 
not  quite  to  redness,  when  plaoed  in  detonating  giu.  They  lose  the 
power,  however,  in  the  course  of  an  hour  or  two ;  out  it  may  be  restored 
by  ignition  and  gradual  cooling,  or  to  a  still  greater  degree  by  nitric  or 
hydrochloric  acid :  in  the  latter  caae,  the  filings,  if  kept  in  a  close  vessel, 
retain  their  power  for  several  days.  When  exposed  to  a  current  of  air 
they  lose  their  power,  bnt  not  so  quickly  as  the  wire.  Insuhition  has  uo 
eifect  on  them.  Platinum  filings  prepared  under  water  exert  no  action 
at  ordinary  temperaturen.     (Dulong  &  Tht  nard.) 

Extremely  fine  platinum  foil  newly  beaten  out,  iind  crumpled  together 
like  the  wadding  of  a  charge  (not  smooth,  or  wound  round  a  glass  rod) 
explodes  detonating  gas  at  ordinary  temperatures.  It  loses  tbis  property, 
however,  by  exposure  to  the  air  for  a  few  minutes,  bat  recovers  it  by 
ignition  in  a  covered  platinum  crucible.  If  kept  in  a  close  vessel,  it 
retains  its  power  for  twenty-four  hours.  But  if  it  be  merely  taken  out, 
unfolded,  and  crumpled  together  again,  its  power  of  causing  explosion  is 
flooe;  and  it  afterwards — like  thicker  platinum  foil — requires  to  be 
heated  to  between  200^  and  dOO*',  before  it  will  iudace  the  formation  of 
watec;  and  even  then,  the  combination  takes  place  without  explosion. 
(Dulong  k  Thenard.) 

In  order  that  a  plate  of  platinum  may  effect  the  combination  of 
detonating  gas,  its  surface  must  be  free  from  all  impurities.  J^repared 
platinum  plate$  for  this  purpose  may  be  obtained  by  the  following 
process,  (a.)  Two  plates  of  platinum  are  used  as  the  electrodes  of  a 
powerful  battery,  and  made  to  decompose  dilute  sulphuric  acid  of  specific 
gravity  1*836,  for  the  space  of  five  minutes.  The  plate  which  forms  the 
cathode  exhibits  but  feeble  action  on  detonating  gas;  and  if  the  solphurie 
acid  is  contaminate  with  metal  or  other  impurities  which  deposit  them- 
selves on  the  negative  electrode,  it  exerts  no  action  whatever.  But  the 
plate  which  has  conducted  the  positive  electricity  into  the  sulphuric  acid 
acts  very  eneigeticaily.  If  then  the  two  electrodes  be  fused  into  the 
upper  part  of  a  glass  tube  filled  with  dilute  sulphuric  add,  and  inverted 
in  that  liquid — so  that  the  detonating  gas  evolved  from  the  liquid  may 
surround  the  nlatinum  plates— it  will,  when  tlie  action  of  the  current 
ceases,  gradually  disappear.  If  the  positive  plate  be  taken  out  of  the 
acid,  washed  with  water,  and  immersed  in  detonating  gas,  it  induces  the 
combination  of  the  oxygen  and  hydrogen,  first  slowly,  then  with  con- 
tinually  increasing  quickness,  often  Mcoming  heated  to  redness,  and 
(after  from  thirteen  to  forty  minutes)  eansinff  the  gas  to  explode.  If  no 
explosion  takes  place,  and  the  gas  is  renewed  as  fast  as  it  condenses,  the 
action  oootinnally  diminiehes,  and  finally  ceases:  it  continues  longer, 
however,  in  proportion  to  the  purity  of  the  oxygen  and  hydrogen  gas3s 
employed — ^longest,  therefore,  when  the  detonating  gas  has  been  obtained 
by  electrolysis.  Mere  washing  with  water  does  not  render  the  plate  so 
active  as  immersion  in  water  &r  a  quarter  of  an  hour;  for  by  the  latter 
treatment,  the  sulphuric  acid  still  aahering  to  the  plate  is  more  effectually 
removed.  If  the  plate  be  washed  with  water,  then  dried  with  linen,  and 
then  the  washing  and  drying  repeated,  it  will  act  in  detonating  gai*  with 
still  greater  quickness,  in  consequence  of  its  dryness.  If,  after  drying,  it 
be  heated  to  redness  in  the  flame  of  a  spirit-lamp,  it  will  act  equally  well; 
but  after  stronger  ignition  in  the  flame  of  alcohol,  urged  by  the  blow- 


48  HYDROGEN. 

pipe,  its  action  is  weaker :  its  power  is  likewise  diminished  if  the  alcohol 
contains  any  impurities,  snch  as  salts,  or  if  it  deposits  soot.  The  pre* 
pared  plate,  if  exposed  to  the  air,  loses  its  power  in  twelve  honrs  at  the 
ntmost,  but  retains  it  for  a  week  if  kept  in  a  sealed  glass  tube,  for  a 
still  longer  time  if  immersed  in  sulphuric  acid  or  solution  of  potash,  and 
for  fifty-three  days  when  kept  in  pure  water;  whereas,  if  the  water  has 
been  left  to  stand  in  wooden  ressels,  the  power  is  destroyed  in  forty 
hours.  Moreover,  a  platinum  plate  which  has  been  used  as  the  anode  in 
sulphuric  acid  of  a  greater  or  less  degree  of  concentration  than  1*836,  or 
in  aqueous  solution  of  nitric,  oxalic,  tartaric,  citric,  or  acetic  acid,  or  of 
phosphate,  chlorate,  or  nitrate  of  potassa,  sulphate  of  soda,  or  sulphate  of 
copper,  exhibits  equal  activity.  In  hydrochloric  acid  it  acquires  less 
power,  stil]  less  in  carbonate  of  potassa  or  soda,  and  none  at  all  in  caustic 
potassa.     (Faraday.) 

(&.)  A  degree  ot  activity  equal  to  that  produced  by  the  electric  method 
may  be  imparted  to  the  plate  by  rubbing  it  while  held  in  the  alcohol 
flame  with  a  piece  of  hydrate  of  potassa,  keeping  the  fused  deposit  in  the 
liquid  state  for  two  minutes,  then  holding  the  plate  in  water,  and  waving 
it  about  for  five  minutes,  afterwards  dipping  it  for  one  minute  into  hot 
oil  of  vitriol,  and  finally  washing  it  for  a  quarter  of  an  hour  in  pure  water. 
Borax  or  carbonate  of  soda  may  likewise  be  used  instead  of  hydrate  of 
potassa.  The  following  methods  may  also  be  used,  but  they  are  less 
efficacious.  Fusion  of  borax  or  carbonate  of  soda  on  the  plate,  and  wash- 
ing with  water,  makes  it  moderately  active.  Merely  heatmg  the  plate  for 
a  minute  in  oil  of  vitriol  and  then  washing  it  with  water  makes  it  very 
active ;  but  if  the  sulphuric  acid  be  removed  by  ignition  instead  of  by 
washing,  it  becomes  inactive,  because  the  acid  leaves  impurities  behind  it. 
Boiling  with  nitric  acid,  especially  the  concentrated  acid,  and  then  wash- 
ing with  water,  produces  a  very  active  plate.  Heating  with  dilute  sul- 
phuric, tartaric,  or  acetic  acid  is  only  occasionally  efficacious,  according  to 
the  nature  of  the  impurities.  Boilmg  in  solution  of  potassa  sometimes 
produces  a  very  active  plate,  at  other  times,  has  no  effect  whatever,  the 
result  depending  on  the  kind  of  impurities  to  be  removed.  A  plate  which 
is  not  rendered  active  by  this  method  becomes  so  after  subsequent  scour- 
ing with  emery  and  solution  of  potassa.  Many  plates  become  active  by 
ignition  in  the  flame  of  a  spirit>lamp ;  others,  not.  Some  which  have 
been  rendered  active  in  the  ordinary  alcohol  flame  lose  their  power  by 
ignition  in  the  same  flame  urged  by  the  blow-pipe ;  either  because  many 
of  the  impurities  present  become  more  firmly  fixed  by  strong  ignition,  or 
because  impurities  are  introduced  from  the  flame  itself,  perhaps  even 
carbide  of  platinum  formed.  Rubbing  with  emery  and  dilute  sulphuric 
acid  or  solution  of  potassa,  by  means  of  a  cork,  makes  the  plate  tolerably 
active  ;  rubbing  with  wood-ash,  with  water  and  cork,  with  chalk  and  water, 
charcoal  and  water,  or  satin-paper  and  water,  is  less  efficacious.  (Faraday.) 

Plates  of  platinum  prepared  according  to  the  methods  described  in 
a  and  6,  rub  together  in  a  peculiar  way,  and  even  after  ignition  are  easily 
and  uniformly  wetted  by  pure  water ;  when  used  as  electrodes,  they  evolve 
gas  at  all  points  of  their  sur£suse,  none  of  which  properties  are  possessed  by 
ordinary  platinum.  By  exposure  to  the  air  for  four  and  twenty  hours, 
the  platinum  loses  these  properties,  but  regains  them  after  being  gently 
heated.  (Rock-crystal  and  obsidian,  likewise,  cannot  be  wetted  uniformly 
till  they  have  been  treated  with  oil  of  vitriol  and  water,  and  then,  after 
drying,  with  water  again  ;  they  also  lose  this  property  after  exposure  to 
the  air  for  24  hours,  or  wiping  with  the  cleanest  linen.)     Faraday. 


FORMATION  OF  WATER.  49 

Spongy  Platinum,  that  is,  platinum  in  the  loosely  coherent  state  in 
which  it  is  obtained  by  gentle  ignition  of  the  ammonio-chloride  (NH*C1, 
PtCP),  indnces,  at  ordinary  temperatures,  the  combustion  of  hydrogen 
mixed  with  oxygen  or  atmospheric  air — first  the  slow,  then,  when  it 
attains  a  red  heat,  the  rapid  combustion.  At  or  near  0%  the  ignition  of 
the  platinum  takes  place  more  slowly  than  at  higher  temperatures.  And 
even  when  a  gaseous  mixture  contains  hydrogen  ^as  mixed  with  an 
extremely  small  quantity  of  oxygen,  or  oxygen  mixed  with  an  extremely 
small  quantity  of  nydrogen,  the  presence  of  spongy  platinum  will  cause 
the  slow  formation  of  water  to  go  on,  till  the  whole  of  the  gas  which  is 
present  in  the  smaller  quantity  is  conyerted  into  water.     (Dobereiner.) 

To  obtain  spougy  platinum  of  the  greatest  possible  degree  of  efficiency, 
it  is  necessary  to  use  very  pure  platinum.  The  foil  or  filings  used  (more 
particularly  the  latter)  is  first  free<l  by  concentrated  hydrochloric  acid 
from  any  iron  which  may  be  adhering  to  it  (as  the  iron  would  otherwise 
be  precipitated  together  with  the  ammonio-chloride  of  platinum,  and 
weaken  the  igniting  power),  then  boiled  in  strong  nitric  acid,  and  after- 
wards dissolved  in  aqua  regia.  The  solution  thus  obtained  is  evaporated 
to  the  consistence  of  syrup, — ^mixed  with  strong  nitric  acid, — ^poured  oif 
from  any  insoluble  matter  that  may  remain — ^mixed  in  the  cold  with  a 
small  quantity  of  distilled  water — ^precipitated  by  a  concentrated  solution 
of  sublimed  sal-ammoniac  in  pure  water,  which  may  be  previously  mixed 
with  a  little  alcohol — the  liquid  poured  off  from  the  precipitated  ammonio- 
chloride  of  platinum — and  the  precipitate  repeatedly  washed  with  cold  dis- 
tilled water :  if  it  be  not  thoroughly  washed,  the  spongy  platinum  obtained 
by  igniting  it  is  not  of  a  whitish  but  of  a  blackish  grey  colour,  and  has 
but  little  power  of  inflaming  the  gas.  It  is  likewise  advants^eous  to 
give  the  precipitate  one  strong  ignition  after  saturating  it  with  alcohol  of 
80  per  cent.,  and  then  wash  it  four  times  with  water.  Lastly,  the  precipi- 
tate is  to  be  moistened  with  a  small  quantity  of  ammonia  and  then  ignited 
again.  Spongy  platinum  thus  prepared  is  capable,  even  after  the  lapse  of 
12  days,  of  inflaming  detonating  gas  at  a  temperature  of  2*5^.  (R.  Bottger, 
Schw.  63,  370 ;  QB,  390.^  The  sal-ammoniac  used  for  precipitating  the 
platinum  solution  must  be  sublimed,  because  that  which  has  not  been 
thus  treated  often  contains  fixed  salts.  It  is  better  to  wash  the  spongy- 
platinum  immediately  after  ic^iting  the  ammonio-chloride  than  to  wash 
the  latter  before  ispition.  (Mohr.)  Spongy  platinum,  which  has  been 
too  stronffly  ignited,  is  incapable  of  producing  explosion,  but  still  induces 
slow  combustion.  (Dulong  k  Th^nard.)  For  making  the  platinum  balls 
already  mentioned  (p.  26)  meersdMum,  either  natural  or  artificial,  is  pre- 
ferable to  clay.  This  substance  is  rubbed  up  with  water  into  a  stiff  pasty 
mass,  then  mixed  with  ammonio-chloride  of  platinum,  and  the  mixture 
formed  into  balls,  small  cups,  &c.,  which  are  slowly  dried  and  then  ignited* 
(Dobereiner,  J.  pr.  Ckem,  17,  158.) 

Spongy  platinum,  when  exposed  to  the  air,  loses  its  power  of  inflaming 
detonating  gas,  sometimes  in  a  few  hours,  sometimes  not  for  several  days 
(Dbbereiner^;  not  so  quickly,  however,  as  platinum  foil  or  filings;  more 
quickly  in  damp  than  in  dry  air;  although  moistening  it  with  water,  or 
passing  aqueous  yapour  over  it,  does  not  sensibly  diminish  its  power. 
(Dulong  &  Th^nard.)  When  spongy  platinum  has  been  thus  exposed 
to  the  air,  and  a  stream  of  hydrogen  mixed  with  air  is  directed  upon 
it,  the  heat  of  the  hand  is  often  sufficient  to  excite  the  combustiou.  Even 
spongy  platinum  moistened  with  water  or  alcohol,  (not  that  which  has 
been  moistened  with  nitrate  of  ammonia  or  caustic  ammonia,)  excites, 

TOL.   II.  B 


50  HYDROGEN. 

when  iniroduoed  into  detonating  gM,  a  slow  formation  of  water,  which 
sometimes  goes  on  for  several  hours.  (D&bereiner.)  The  lost  power  is 
restored  by  ignition  and  oooling  (Dobereiner) ;  likewise  by  moistening 
with  nitric  acid,  and  drying  at  200^  :  the  power  restored  by  the  latter 
method  is  not  destroyed  by  the  action  of  potassa  or  soda.  (Dulong  St 
Thenard.) 

Ammoniacal  gas  destroys  the  inflaming  power;  even  a  drop  of 
solution  of  ammonia  evaporating  in  the  room  is  sufficient  to  produce  this 
effect :  hence,  also,  the  neighbourhood  of  stables  from  which  ammonia  is 
disengaged,  renders  spongy  platinum  inactive.  (Bdttger.)  Nitric  acid 
vapour  or  chlorine  restores  the  power  which  has  been  taken  «way  by 
ammonia;  and  the  spongy  platinum,  before  it  sets  fire  to  the  mixture  of 
air  and  hydrogen,  evolves  fumes  of  the  ammoniacal  salt  produced. 
Hydrosulphurio  acid  gas,  the  vapour  of  sulphide  of  ammonium,  and  more 
especially  ihat  of  sulphide  of  carbon,  destroy  the  inflaming  power;  and 
when  thus  destroyed,  it  cannot  be  restored  by  the  action  of  nitric  acid  or 
chlorine,  but  only  by  the  application  of  heat  considerably  below  redness. 
(Schweigfler,  Sokw.,  63,  875.)  Since  hydrosulphurio  acid  gas  is  some- 
times evolved  during  the  solution  of  zinc  in  sulphuric  acid,  its  accidental 
presence  in  the  detonating  gas  may  destroy  the  power  of  the  spongy 
platinum;  ignition  will,  however,  restore  its  activity.  (Artns,  J.  pr, 
Chem,  6,  176.)  Immersion  for  a  time  in  carbonic  or  hydrochloric  acid 
ffas  rather  heightens  the  inflaming  power  of  spongy  platinum. 
(Ddbereiner.) 

A  platinum  ball  kept  over  mercury  becomes  inactive  in  four-and« 
twent^r  hours.  Immersed  in  a  vessel  filled  with  oxygen,  hydrogen, 
carbonic  aoid  gas,  or  air,  it  remains  active :  if  left  for  five  minutes  in 
hydrochloric  acid  gas,  it  loses  part  of  its  power ;  still  more  in  defiant  gas^ 
or  coal  gas;  and  if  immersed  for  the  same  time  in  sulphurous  acid, 
hydrosulphurio  acid,  or  ammoniacal  gas,  it  becomes  completely  inactive. 
If  moistened  with  water,  its  action  on  detonating  gas  is  very  feeble  at 
first,  but  gradually  increases  as  the  water  evaporates.  A  ball  moistened 
with  sulphuric,  nitric,  or  hydrochloric  acid,  has  no  action  on  detonating 
gas.  One  that  has  been  moistened  with  alcohol  or  ether  acts  slowly  at 
first,  but  the  action  increases  more  rapidly  than  in  the  case  of  the  ball 
moistened  with  water.     (Turner.) 

The  spongy  platinum  used  in  Ddbereiner's  In»tantaneou$  Light 
Machine  loses  its  power  from  the  following  causes  :  1.  Fine  particles  of 
dust  in  the  air  leave  their  ashes  upon  it  as  they  bum.  2.  Sulphate  of 
zinc  carried  forward  by  the  hydrogen,  forms  on  the  spongy  metal  an 
alloy  of  line  and  platinum,  by  reduction  of  the  sine  during  the  action  of 
the  Wrning  hydrocen,  whereby  the  spongy  platinum  becomes  hard  and 
somewhat  malleable,  and  loses  all  its  activity.  The  power  may  however 
be  restored  by  heating  the  metal  with  oil  of  vitriol  in  a  porcelain  capsule, 
for  a  onarter  of  an  hour,  till  the  aoid  begins  to  evaporate,  then  boiling 
it  well  in  water  six  times,  till  it  no  longer  reddens  litmus  paper.  Driving 
off  the  sulphuric  acid  by  ignition  destroys  the  power  of  the  platinum; 
because  the  alkali,  which  the  acid  has  taken  up  from  the  dish,  remains 
on  the  metal  in  the  form  of  a  thin  film.     (Mohr,  Ann.  Pharm.  18,  SS,) 

Flaiinumrpaptr-iuh.  White  bibulous  paper  saturated  three  times 
with  solution  of  ammonio-chloride  of  platinum,  and  then  burnt,  leaves  a 
delicate  and  finely  divided  residue  of  platinum  of  the  form  of  the  paper, 
which  sets  fiie  to  a  mixture  of  air  and  hydrogen  gas,  even  more  quiddy 
than  spongy  platinum.    (Pleischl.)    Platinum  thus  prepared  is  very 


FORMATION  OF  WATBR.  51 

totire^  and  tb«  more  bo,  the  ffraaier  its  purity.  If  pB/pet,  three  timee 
iaturated  with  solution  of  ohloride  of  platinum  be  bumt^  the  ash  will 
exhibit  its  power  at  temperatures  nearly  as  low  as  —  20°  (  ^  4""  F.)  :  at 
this  temperature,  howerer,  its  action  ceases  altogetheri  but  immediately 
recommences  when  the  cooling  b  diminished.  The  ash  retains  its  power 
after  exposure  to  the  air  for  a  considerable  time.  If  it  should  not 
exhibit  its  full  power,  it  may  be  restored  to  its  former  state  by  boiling 
in  nitric  acid,  and  subsequent  ignition  at  a  tolerably  high  temperature. 
On  surrounding  a  thermometer  bulb  with  this  ash,  placing  it  in  a  perfect 
vacuum,  and  allowing  a  stream  of  hydrogen  gas  to  flow  upon  it,  no 
rise  of  temperature  ensues;  but  if  air  he  allowed  to  enter  till  the 
tension  becomes  equiyalent  to  1^  inch  of  mercury,  the  ash  becomes  red* 
hot  when  the  hydrogen  is  directed  upon  it;  although,  in  this  case,  the 
oxygen  gas  is  18  times  more  expanded  than  in  common  air.  (De  la 
Riv^  &  Marcet,  Ann,  Ghim,  Pkys.,  39,  828.) 

Platinum  redtvced  to  Lamina.  A  mixture  of  the  aqueous  solutions  of 
chloride  of  platinum  and  tartrate  of  soda  is  heated  in  a  glass  tube,  80 
inches  long  and  }  of  an  inch  wide,  till  it  begins  to  grow  turbid,  and  then 
exposed  to  sunshine  for  sereral  days.  The  mater  part  of  the  platinum 
ie  then  reduced  and  deposited  on  the  sides  of  the  tube  in  thin  dark-grey 
lamins.  The  tube  with  the  liquid  is  inverted  in  a  reseel  containing 
water,  and  then  filled  with  hydrogen  gas :  by  this  treatment,  the  pla- 
tinum acquires  a  silvery  whiteness,  and  becomes  easily  separable  from  the 
tube  by  mechanical  means.  It  possesses  considerable  inflaming  power. 
(Dbbereiner,  Sckw,  47,  133.) 

Flatinum-black,  This  name  is  given  to  pktinum  reduced  from  an 
aqueous  solution  in  a  very  finely  divided,  perhaps  amorphous  state,  and  in 
the  form  of  a  delicate  black  powder.  [For  the  several  modes  of  preparing 
it,  vid.  Platinum.]  It  instantly  sets  fire  to  a  mixture  of  air  and  h  vorogen 
gas;  but  passes,  in  consequence  of  the  ignition  which  it  sufiers  at  the  same 
time,  into  a  state  resemoling  spongy  platinum.  Platinum-black  when 
newly  prepared  absorbs  with  avidity  a  large  quantity  of  oxygen  gas  from 
the  air,  but  little  or  no  nitrogen.  Consequently,  when  introduced  into 
pure  hydrogen  gas  standing  over  mercury,  it  converts  a  considerable  qnan« 
tity  of  that  gas  into  water,  by  causing  it  to  combine  with  the  oxygen  which 
it  has  itself  absorbed.  On  being  subsequently  exposed  to  the  air,  it 
becomes  charged — ^provided  its  state  of  aggregation  has  not  been  too  muck 
altered  by  the  previous  ignition-^with  about  as  much  oxygen  gas  as  it 
contained  before,  and  thereby  regains  the  power  of  burning  hydrogen : 
and  thus  the  action  ma^  be  several  times  repeated.  10  grains  of  platinum- 
black  prepared  with  amc  condense  0*42  cub.  in.  of  hydrogen  gas;  conse- 
quently must  have  absorbed  0*21  cub.  in.  of  oxygen;  10  grains  prepared 
with  sugar  condense  0*75  cub.  in.,  and  10  grains  prepar^  by  E.  Davy's 
process  condense  1  *10  cub.  in.  of  hydrogen,  and  therefore  the  latter  must 
have  absorbed  0*55  cub.  in.  of  oxygen  gas.  Estimating  the  specific  gravity 
of  platinum-black  at  16*000,  it  will  follow  that  1  volume  of  platinum- 
black  prepared  by  zinc  absorbs  97  volumes;  1  volume  of  the  same  pre- 
pared oy  sugar  absorbs  173  volumes;  and  1  volume  of  that  prepared  by 
E.  Davy*8  process  absorbs  253  volumes  of  oxy^n  gas.  It  appears  then 
that  platinum-black  absorbs  oxygen  and  carries  it  oyer  to  combustible 
bodies.  (D5bereiner,  J.  pr.  Ohm.  1,  114.— Jnn.  Pharm.  14,  10.)  10 
grains  of  platinum-black  introduced  into  hydrogen  gas  standing  over  mer- 
euiy  convert  0*98  cub.  in.  of  it  into  water;  must  therefore  have  absorbed 
0-40  enb.  in.  of  oxygen.    (W.  Henry,  PhU.  Mag.  J.  6,  364.)    When 

e2 


52  HTDROGEN. 

platinmn-black  is  digested  in  dilnte  hydrochloric  acid,  the  oxygen  which 
]t  holds  combines  with  the  hydrogen  of  the  fM;id,  and  there  results,  partly 
bichloride  of  platinum,  which  remains  dissolved,  partly  protochloride  of 

Slatinnm,  which  sticks  about  the  substance  and  destroys  its  igniting  power; 
tgestion  in  caastic  potassa  will  however  render  it  active  again.  Ammo- 
niacal  gas  instantly  destroys  the  power  of  platinum-black;  but  it  may  be 
restored  to  its  former  state  by  the  application  of  a  gentle  heat,  or  by  lightly 
blowing  hydrochloric  acid  gas  upon  it.  (Dobereiner,  Ann.  Fharm.l,  29.) 
Iridium. — Spongy  Iridium,  obtained  by  ignition  of  the  ammonio-chlo- 
ride,  becomes  strongly  heated  in  detonating  gas  and  produces  water,  the 
action  not  being  attended  with  explosion.  (Dulong  k  Thenard.)  It 
possesses  greater  igniting  power  than  spongy  platinum,  and  does  not  lose 
it  so  readily  on  exposure  to  the  air :  its  power  is  however  destroyed  by 
ammonia.  (Dobereiner.) — Iridium-black,  prepared  by  exposing  a  mixture 
of  sulphate  of  iridium  and  alcohol  to  sunshine,  thoroughly  washing  the 
precipitate  thus  obtained  with  nearly  boiling  water,  and  then  drying  it  at 
100°,  instantly  sets  fire  to  detonating  gas.  (Dobereiner,  Schw.  63,  465.) 

Spongy  Osmium  induces  the  formation  of  water  at  temperatures  between 
40''  and  50\  and  spongy  Khodium  at  240"".  (Dulonff  &  Thenard.) 

Palladium  in  the  state  of  foil  or  filings  behaves  like  platinum.  Spongy 
palladium  ignites  detonating  gas  at  ordinary  temperatures.  (Dulong  k 
Thenard.)  Palladium  foil  may  be  prepared  in  the  same  manner  as  plati- 
num, either  by  the  electric  current  in  dilute  sulphuric  acid,  or  by  heating 
in  oil  of  vitriol  (pp.  47,  48) ;  in  either  case,  however,  the  action  of  the 
acid  must  not  be  continued  too  long,  or  it  may  dissolve  some  of  the  palla* 
dium.  (Faraday.)  Pulverulent  palladium  obtained  by  ignition  of  the 
cyanide,  becomes  heated  to  redness  in  a  stream  of  hydrogen  gas  and  com- 
mon air,  and  causes  detonation:  its  action  is  however  less  powerful  than 
that  of  spongy  platinum;  strongest  when  the  palladium  is  placed  in  a  hole 
in  a  piece  of  charcoal,  and  the  hydrogen  directed  upon  it.  (Pleischl.) 
Palladium-paper-ash  acts  almost  as  strongly  as  platinnm-paper-ash  (p.  50), 
the  more  so  in  proportion  to  the  purity  of  the  palladium:  it  does  not  lose 
its  power  by  exposure  to  the  air,  even  for  a  considerable  time.  (De  la  Rivd 
k  Marcet.) 

Odd  in  thin  leaves  acts  on  detonating  gas  at  260^ — in  somewhat 
thicker  leaves,  at  280°.  Gold-dust  precipitated  from  solution  by  zinc, 
and  dried  at  a  low  temperature,  does  not  act  below  120°;  but  after  ignition 
it  acts  at  55"^.  (Dulong  &  Thenard.)  Gold  leaf  may  also  be  made  active 
by  electricity,  or  by  heating  in  oil  of  vitriol.  (Faraday.)  Gold-paper-ash 
does  not  act  below  50°.  (De  la  Rive  &  Marcet.) 

Silver-leaf  BctB  less  powerfully  than  gold-leaf,  but  at  temperatures 
below  the  boiling  point  of  mercury.  Silver  in  the  pulverulent  state,  as 
precipitated  from  its  solutions  by  zmc  and  ignited,  acts  at  150°.  (Dulong 
&  Th^nard.^  Silver  cannot  be  prenared  by  the  action  of  the  electric 
current  in  dilute  sulphuric  acid,  or  by  heating  it  in  oil  of  vitriol.  (Faraday.) 
Silver-paper-ash  becomes  red-hot  in  detonating  gas  at  temperatures  between 
120''  and  150°.  (De  la  Rive  &  Marcet.)  Silver  reduced  from  its  oxide 
by  heating  in  an  atmosphere  of  hydrogen,  also  requires  an  elevated  tem- 
perature to  make  it  act.  (W.  Ch.  Henry.) 

Copper  reduced  from  the  oxide  of  hydrogen,  and  heated  in  the  air  to 
264°,  while  a  stream  of  hydrogen  gas  is  directed  upon  it,  does  not  set  fire  to 
the  gas,  but  merely  becomes  oxidated.  At  a  higher  temperature  it  becomes 
heated  to  redness,  inasmuch  as  it  continually  gives  np  to  the  hydrogen  the 
oxygen  which  it  has  previously  absorbed,  and  takes  up  a  fresh  quantity  of 


FORMATION  OP  WATER.  53 

oxyj3^cu ;  and  the  state  of  ijBmition  continues^  even  after  the  supply  of  heat 
from  without  has  been  discontinued.  Similar  effects  are  exnibited  bj 
nickel  and  cobalt.  Iron  reduced  from  its  oxide  by  hydrogen  gas  likewise 
induces  the  rapid  combustion  of  the  gas  at  the  temperature  at  which  the 
reduction  takes  place.  Lead  reduced  by  hydrogen  has  no  action.  Turn- 
ings of  copper  or  iron,  zinc  foil,  and  charcoal,  do  not  act  upon  detonating 
gas  below  the  boiliug  point  of  mercunr.  (W.  C.  Henry.)  Cobalt  and 
nickel  in  mass  act  at  300''.  ^Dulon^  <k  Th^nard.) 

Charcoal  (Sir  H.  Davy  found  that  a  feebly  glowing  coal  induces  slow 
combination),  pumice-stone,  porcelain,  rock-crystal,  and  glass  (compare  the 
observation  of  Grotthuss  and  Davy,  mentioned  on  page  25),  act  below 
350^:  the  action  of  fluor-spar  is  very  weak.  Angular  pieces  of  glass-  cause 
the  formation  of  twice  as  much  water  in  a  given  time  as  rounded  pieces  of 
equal  surface.  Mercury  heated  nearly  to  the  boiling  point  does  not  appear 
to  induce  the  formation  of  water.  (Dulong  &  Th^nard.) 

Other  gases  mixed  with  the  detonating  gas  hinder  or  completely  stop 
the  action  of  platinum  and  the  other  metab  above  named. 

When  one  volume  of  detonating  gas  is  mixed  with  different  quantities 
of  the  following  gases,  and  spongy  platinum  introduced  into  the  mixture, 
the  metal  is  found  to  produce  its  effect  in  the  presence  of  10  volumes  of 
oxvgen,  hydrogen,  nitrogen,  or  marsh-gas,  and  of  6  volumes  of  hydro- 
chloric acid  gas :  on  the  contrary,  the  action  is  either  prevented  or  very 
much  retarded  by  11  volumes  of  nitrous  oxide,  3  volumes  of  carbonic 
acid,  1  ^  volume  of  defiant  gas,  1  volume  of  cyanogen,  or  ^  a  volume  of 
carbonic  oxide.  (W.  Henry,  Ann,  Phil,  25,  426.) 

In  a  mixture  of  1  volume  of  detonating  gas  with  1  volume  of  carbonic 
oxide,  hydrosulphuric  acid,  or  defiant  gas,  in  which  spongy  platinum  is 
inactive,  Liebig  s  platinum-black  instantly  becomes  red-hot,  and  produces 
rapid  combustion.     (W.  Henry,  PhU.  Mag.  J.  6,  364.) 

In  a  mixture  of  1  or  2  measures  of  detonating  gas  and  1  measure  of 
carbonic  oxide,  spongy  platinum  produces  slow  condensation.  A  mixture 
of  1  volume  of  hydrogen  gas  with  nearly  1  volume  of  carbonic  oxide  and 
1  volume  of  oxygen  is  slowly  but  completely  burnt  by  the  action  of  a 
ball  of  platinum,  and  spongy  platinum  often  causes  it  to  explode.  A 
mixture  of  5  volumes  of  hydrogen  gas,  1  volume  of  carbonic  oxide,  and 
3  volumes  of  oxygen,  is  condensed  more  slowly  than  a  mixture  containing 
less  hydrogen.  In  all  these  slow  combustions,  carbonic  acid  and  water 
are  produced  together.  When  the  mixture  contains  1  volume  of  deto- 
nating gas  and  1  volume  of  carbonic  oxide,  •{-  of  the  oxygen  combines 
with  the  carbonic  oxide,  and  \  with  the  hydrogen.  The  greater  the 
quantity  of  carbonic  oxide  in  the  mixture,  the  greater  is  the  quantity  of 
carbonic  acid  produced ;  and  the  greater  the  quantity  of  hyorogen,  the 
greater  is  the  quantity  of  water  produced. 

In  a  mixture  of  equal  volumes  of  detonating  gas  and  defiant  gas,  a 
platinum  ball  first  condenses  the  detonating  gas  alone  j  with  a  larger 
proportion  of  detonating  gas,  more  carbonic  acid  is  produced,  from  com-* 
bustion  of  the  defiant  gas.  In  a  mixture  of  hydrogen,  carbonic  oxide, 
olefiant,  and  oxygen  gases,  the  hydrogen  and  carbonic  oxide  are  oxidized 
by  preference ;  and  if  the  quantity  of  hydrogen  be  small,  and  that  of 
oxygen  insufficient,  the  olefiant  gas  is  scarcely  acted  upon.  In  a  mixture 
of  1  volume  of  detonating  gas  with  from  |  to  10  volumes  of  marsh-gas,  a 
platinum  ball  condenses  the  first  only;  it  is  onl^  when  the  quantity  of  deto- 
nating gas  amounts  to  rather  more  than  five  times  that  of  the  marsh-gas, 
that  a  small  quantity  of  carbonic  acid  is  produced ;— the  carbonic  add  is 


54  HYDROGEN. 

prodaoed  in  greater  quantity  when  a  larger  proportion  of  oxygen  i« 
present,  in  which  case  the  formation  of  carbonic  acid  may  take  plaee 
when  the  quantity  of  detonating  gas  is  more  than  four  times  as  great  as 
that  of  the  marsh-gas.     (W.  Henry.) 

The  action  of  a  ball  of  platinum  on  detonating  gas  is  not  prevented 
by  the  addition  of  the  largest  quantities  of  hjjrdrogen,  oxygen^  carbonic 
acid,  nitrous  oxide,  or  atmospheric  air  j  in  a  mixture  of  -f  of  a  volume  of 
carbonic  oxide  with  I  volume  of  detonating  gas  it  is  tolerably  good;  with 
•)•  of  carbonic  oxide,  very  weak  in  the  cold,  good  when  the  temperature  is 
raised;  and  with  \  of  carbonic  oxide,  it  is  nothing  in  the  cold,  and  very 
feeble  even  on  the  application  of  heat;  with  7V  of  a  volume  of  sulphurous 
acid  gas,  the  action  is  rapid  at  first,  but  ceases  before  the  whole  of  the 
detonating  gas  is  consumed ;  also  with  from  tV  ^  iV  ^^  sulphurous  acid, 
the  platinum  acts  quickly  at  first,  but  soon  becomes  inactive ;  when  the 
quantity  of  sulphurous  acid  amounts  to  -^^  no  action  takes  place,  not 
even  on  warming.  With  ^  of  a  volume  of  hvdrosulphuric  acid  gas,  the 
action  is  rapid  at  first,  but  ceases  before  the  whole  is  consumed ;  with  ^ 
of  a  volume  of  the  same  gas  there  is  a  very  slow,  imperfect  action ;  and 
with  ^,  no  action  at  all,  not  even  on  heating.  With  ^  of  a  volume  of 
hydrochloric  acid  gas,  rapid,  perfect  action ;  with  3  volumes,  slow,  but 
still  perfect  action ;  with  5  volumes,  very  slight.  With  -^  of  a  volume  of 
ammoniacal  gas,  rapid  action;  with  -1^,  slow^  but  perfect;  with  ^,  none  in 
the  cold,  strong  at  higher  temperatures.  In  those  cases  in  which  the 
platinum  was  heated,  it  was  brought  to  such  a  temperature  as  just  to 
bum  the  hand.     (Turner,  Ed.  J.  of  Sc,  12,  311.) 

Prepared  platinum  foil  acts  as  follows  on  one  volume  of  detonating 
ffas  with  various  other  gases.  The  smallest  retarding  action  is  exerted 
by  nitrons  oxide;  then  follows  hydrogen,  then  nitro^ren;  then  air  and 
oxygen  gas :  in  these  cases,  4  measures  of  the  gases  just  mentioned  were 
mixed  with  1  measure  of  detonating  gas.  Combination  likewise  takes 
place  rapidly  in  presence  of  4  measures  of  carbonic  acid  gas.  Carbonic 
oxide  in  the  proportion  of  from  \  a  volume  to  4  volumes  interrupts  the 
action;  the  platinum  plate,  when  taken  out  of  the  mixture,  is  found  to 
act  perfectly  in  pure  detonating  gas.  In  a  mixture  of  33  measures  of 
detonating  gas,  2  of  carbonio  oxide  and  1  of  oxygen,  the  action  is  slow  at 
first,  but  afterwards  increases,  and  after  40  minutes,  explosion  takes  place. 
Sulphuretted  or  phosphuretted  hydrogen  in  the  proportion  of  from  -^  to 
i^B^  of  a  volume  stops  the  action  completely;  and  the  platinum  is  after* 
wards  inactive,  even  in  pure  detonating  gas.  Vapour  of  sulphide  of 
carbon  likewise  stops  the  action,  without  however  depriving  the  platinum 
of  its  igniting  power.  In  a  mixture  of  one  volume  of  detonating  gas  with 
^  of  a  volume  of  olefiant  gas,  slight  action  takes  pUce  after  50  minutes, 
and  explosion  after  85  minutes.  When  -^oi^^  volume  of  olefiant  gas  is 
present,  explosion  takes  place  in  two  hours;  but  in  a  mixture  of  1  volume 
of  detonating  gas^  ^  of  olefiant  gas,  and  ^  of  oxygen,  no  action  is 
perceptible,  even  in  45  hours.  Ether  vapour  interrupts  the  action, 
though  not  completely;  the  vapour  of  volatile  oils  exerts  a  still  greater 
retardation.  In  these  cases,  tibe  hydrogen  alone  is  slowly  burnt;  tha 
ether  and  Otis  remain  unconsumed.  The  action  of  spongy  platinum  is 
Similar  to  that  of  platinum  foil.     (Faraday.) 

When  hydrogen  nixed  with  various  other  gases  is  directed  in  a  stream 
tkrongh  the  air  on  spongy  platinum,  the  following  results  are  obtained: 
A  nixtore  of  1  Tolume  of  hydroffen  and  6  volumes  of  carbonio  acid 
makes  the  metal  red  hot^  although  the  aame  mixture  does  not  take  fir^  oq 


FORMATION  OF  WATER.  55 

the  application  of  an  ordinary  flame.  A  mixture  of  eoual  volames  of 
hydrogen  and  nitrogen  causes  the  metal  to  glow.  8  volumes  of  hydro- 
gen with  I  volume  of  carbonic  oxide  or  defiant  gas  produce  no  ignition. 
Hydrogen  gas,  charged  with  vapour  of  ether  or  volatile  oils,  makes  the 
platinum  red  hot.  Hydrogen  gai  produced  from  the  decomposition  of 
water  by  red-hot  iron  (p.  43,  3),  even  after  it  has  stood  over  water  for  a 
week  and  has  lost  all  its  disagreeable  odour,  is  not  affected  by  either 
spongy  platinum  or  prepared  platinum  foil ;  even  a  mixture  of  this  gas 
with  8  measures  of  ordinary  hydrogen  fas  and  2  measures  of  oxygen,  is 
not  affected  by  prepared  platinum  foil;  possibly  in  consequence  of  the 
presence  of  carbonic  oxide.  (Faraday,  Eaoperimenial  Re9$arcke$  in  Elee^ 
trieity,  Series  6,  p.  190;  also  Fogg.  3d,  149.) 

It  is  only  impure  defiant  gas  that  prevents  the  action  of  spongy  pla- 
tinum, not  the  pure  gas  which  has  been  well  washed  with  potash.  On  a 
mixture  of  detonating  gas  with  a  large  quantity  of  defiant  gas,  spongy 
platinum  acts  in  a  few  minutes,  but  condenses  only  the  hydrogen  ;  so  that 
in  this  manner  defiant  gas  and  hydroffen  may  be  separated.  Also  the 
vapour  of  ether,  rock-oil,  and  other  volatile  oils  does  not  interfere  with 
the  action  of  spongy  platinum  on  detonating  gas  :  on  the  contrary,  when 
ether  is  present,  the  spongy  metal  becomes  so  strongly  heated  that  a  small 
portion  of  the  ether  is  burnt  at  the  same  time^  and  produces  carbonic  acid. 
(Graham,  N.  Qu.  J.  of  8c,  6,  354^. 

In  a  mixture  of  1  volume  of  detonating  gas  and  from  Vv  ^  tV  ^^  ^^~ 
bonic  oxide,  prepared  platinum  foil  produces  a  slight  diminution  of  volume 
in  the  course  of  24  hours ;  spouffy  platinum  causes  a  trifling  diminution  in 
five  minutes,  and  a  considerable  decrease  in  two  hours.  When  the  mixture 
contains  ^  of  its  volume  of  carbonic  oxide,  the  condensation  is  slower, 
amounting  to  only  -^  in  a  day  :  in  this  action  there  is  always  produced, 
together  with  a  small  quantity  of  water,  a  proportionally  large  quantity 
of  carbonic  acid.  When  1  volume  of  oxysen  is  mixed  with  2  volumes  of 
hydrogen  and  2  volumes  of  carbonic  oxide,  the  latter  takes  up  8  or  10 
times  as  much  oxygen  as  the  former.  Consequently,  carbonic  oxide  does 
not  prevent  the  action  of  platinum,  but  only  retards  it,  perhaps  because  it 
appropriates  the  oxygen  to  itself.  On  a  mixture  of  1  volume  of  detouatinf 
gns  and  -^  of  a  volume  of  defiant  gas  purified  by  potash,  the  prepared 

Slatinum  plate  acts  in  the  first  minute;  in  10  minutes,  \  of  the  gas  is  con- 
ensed ;  in  15  minutes,  ^  ;  the  plate  becomes  heated  &f  above  the  boiling 
point  of  water,  and  only  -^  of  the  mixture  remains  uncondensed.  Even 
when  the  defiant  gas  amounts  to  -^,  the  action  is  perceptible  in  the  first 
quarter  of  an  hour,  and  complete  in  two  days.  The  action  of  spongy 
platinum  is  not  at  all  retarded,  even  by  ^  a  volume  of  defiant  gas.  In  a 
mixture  of  equal  volumes  of  olefiant  gas  and  detonating  gas,  spon^  pla- 
tinum acts  instantaneously,  but  condenses  only  half  of  the  gee  ;  and  none 
of  the  residual  gas  is  absorbed  by  potash.  With  three  measures  of  defiant 
gae,  spongy  platinum  produces  no  condensation  till  after  some  hours.  A 
mixture  of  1  volume  of  detonating  gas,  and  even  20  volumes  of  defiant 
gas  is  condensed  by  Liebig's  platinum-black.  In  some  of  these  cases,  a 
very  small  quantity  of  Gar£>nic  acid  is  produced ;  in  others,  none  at  alL 
All  gases  which  retard  or  prevent  the  action  of  platinum,  have  themselres 
flome  degree  of  afllnity  for  oxygen.     (W.  Ch.  Henry.) 

Of  the  various  explanations  which  have  been  offered  of  this  remarkable 
property  of  platinum  and  ether  metals,  the  following  by  De  la  Rive  is  by 
M  the  most  probable.  Platinum  in  the  air  or  in  o^ffm  gM  becomei 
covered,  even  at  ordinary  temperatures,  with  a  very  thin  film  of  platinous 


56  HYDROGEN. 

or  platinic  oxide  :  at  the  same  time,  the  hydrogen  acting  upon  this  oxide, 
even  in  the  cold,  reduces  the  platinum  to  the  metallic  state  again,  and 
forms  water.  Hence  when  oxygen  and  hydrogen  act  simultaneously  on 
platinum,  a  continued  series  of  oxidations  and  reductions  takes  place,  as 
individual  points  of  the  metal  come  in  contact,  first  with  oxygen,  and  then 
with  hydrogen.  The  platinum  acts  therefore  as  the  carrier  of  the  oxygen 
to  the  hydrogen,  which  gases  cannot  of  themselves,  by  reason  of  their 
gaseous  condition,  act  upon  each  other  at  ordinary  temperatures.  The 
rise  of  temperature  which  accompanies  this  transference  accelerates  the 
alternate  oxidation  and  reduction  of  the  platinum ;  and  the  metal  ulti- 
mately becomes  heated  to  redness,  at  which  temperature  it  is  capable  of 
inducmg  the  direct  combination  of  the  oxygen  and  hydrogen.  This  theory 
is  supported  by  the  following  considerations.  De  la  Rive  has  shown 
(I.,  446,  447),  that  a  platinum  plate  actine  as  anode  in  the  decom- 
position of  water,  oxidates  on  the  surface :  also  that  the  plate  oxidates 
when  exposed  to  the  air ;  inasmuch  as,  when  subsequently  used  as  the 
cathode,  it  evolves  less  hydrogen  at  first  than  afterwards.  Moreover,  that 
when  the  current  is  made  to  pass  through  the  water  alternately  in  opposite 
directions,  both  platinum  electrodes  become  covered  with  a  fine  dust  of 
platinum,  produced  by  repeated  oxidation  and  reduction.  The  same  phe- 
nomenon is  apparent  when  combustion  takes  place  on  the  surface  of  pla- 
tinum. A  spiral  of  platinum  wire  fixed  at  the  end  of  a  glass  tube  from 
which  hydrogen  gas  issues  into  the  air — so  that  the  wire  constantly 
remains  at  a  red  heat — ^becomes  corroded  and  covered  with  a  powder, 
which  is  first  grey  and  afterwards  black.  The  same  effect  is  produced, 
but  with  greater  rapidity,  even  in  48  hours,  in  the  lamp  without  flame 
(vid.  Alcohol).  In  consequence  of  the  greater  surface  of  platinum  thus 
formed,  the  platinum  acts  more  strongly,  glows  throughout  a  greater 
length,  and  much  more  brightly — as  was  first  observed  by  Pleischl,  and 
afterwards  confirmed  by  De  la  Rive.  The  activity  of  platinum  increases 
as  its  sur&ce  is  more  finely  divided,  because  a  more  rapid  oxidation  is 
thereby  brought  about.  Hence  spongy  platinum  acts  more  strongly  than 
platinum  foil,  and  platinum-black  most  strongly  of  all.  With  the  last, 
Dobereiner  has  actually  observed  a  rapid  absorption  of  oxygen  to  take 
place  (p.  51).  The  behaviour  of  platinnm-black  with  hydrogen  gas  and 
dilute  hydrochloric  acid  leads  to  the  same  conclusion.  It  is  true,  on  the 
other  hand,  ^that  Matteucci  and  W.  C.  Henry  observed  that  platinum  foil 
and  spongy  platinum  absorbed  a  small  quantity  of  hydrogen  gM  and  no 
oxygen ;  bnt  the  experiment  was  made  with  platinum  already  a  little  oxi- 
dated in  the  air,  so  that  the  oxide  formed  upon  it  condensed  the  hydrofi;en. 
Platinum  foil  prepared  according  to  Faraday's  method  absorbs,  according 
to  De  la  Rive,  no  hydrogen  gas  but  only  oxygen.  The  oxygen  does  not 
adhere  loosely  to  the  platinum,  but  combines  with  it  and  forms  an  oxide; 
for,  according  to  De  la  Rive,  it  cannot  be  removed  by  gentle  rubbing  with 
linen,  but  only  by  brisker  rubbing  or  by  boiling  with  an  acid  which  dis- 
solves the  oxide.  Superficial  impurities  in  the  platinum  are  injurious, 
because  they  render  it  less  oxidable  or  less  reducible.  Platinum  is  more 
active  than  other  metals,  because,  on  the  one  hand,  it  has  a  greater  ten- 
dency than  gold,  &c.,  to  become  covered  with  a  film  of  oxide  at  ordinary 
temperatures— and  on  the  other  hand,  the  oxide  of  platinum  gives  up  its 
oxygen  to  hydrosren  and  other  combustible  gases  at  lower  temperatures 
than  are  required  for  the  reduction  of  the  more  oxidable  metals :  conse- 
quently these  latter  require  a  higher  temperature  to  make  them  act 


FORMATION  OF  WATBR.  5? 

(p.  52).  This  explanation  is  not  indeed  applicable  to  the  ease  of  non- 
metallic  bodies;  but  these  do  not  act  till  heated  above  300°. 

Other  JSxpkmations : — 1.  Platinum^  by  yirtae  of  strong  adhesive 
power,  condenses  oxygen  and  hydrogen  gases  on  its  sarfEuse  (I.,  26),  and 
m  this  condensed  state  they  are  capable  of  combining.  (Faraday  and 
others.)  As  the  temperature  of  the  platinum  rises,  the  condensation  of 
the  gases  on  its  surface  ought  to  diminish ;  whereas,  in  reality,  the  action 
increases  in  intensity  as  the  temperature  rises.  2.  Platinum  condenses 
the  combustible  gas  on  its  surface  in  the  form  of  an  envelope ;  and  in  this 
condensed  state,  the  gas  is  capable  of  combining  with  the  surrounding 
oxyeen  at  ordinary  temperatures.  (Fusinieri^  Giom.  di  Fisica,  1825,  8, 
259^  3.  Dulong  &  Tb^nard  discover  a  sort  of  connexion  and  opposi> 
tion  between  die  power  of  metals  to  induce  combination,  and  that  which 
they  also  possess  when  red-hot  of  decomposing  ammonia.  In  platinum^ 
which  possesses  the  former  power  in  the  highest  degree,  the  latter  is  least 
developed ;  iron,  on  the  contrary,  exhibits  the  first-mentioned  faculty  in 
the  smallest,  and  the  last  in  the  greatest  degree.  4.  D5bereiner  and 
Schweig^r  seek  to  explain  the  phenomena  in  various  ways  by  reference 
to  electrical  relations. 

Platinum  Instantaneous  Light  Apparatus,  or  Dobereiner^s  Imtantaneaus 
Light  Apparatus. — Hydrogen  ^as  is  generated  in  a  glass  vessel  by  means 
of  zinc  and  dilute  sulphuric  acid^  and,  by  opening  a  cock,  made  to  flow  in 
a  fine  stream  on  spongy  platinum,  which  immediately  becomes  red  hot 
and  sets  fire  to  the  gas.  (Ddbereiner,  Schw.  38,  326  ;  39,  159  ;  63,  468. 
— Pfaff,  Schw.  40,  1.— Bottger,  Schw.  68,  390.— Mohr,  Ann.  Phai^.  23, 
228.) 

5f,  Various  organic  substances  in  the  act  of  spontaneous  decomjiosi- 
tion  give  rise,  under  particular  circumstances,  to  the  combination  of 
oxygen  and  hydrogen.  Such  are  peas  and  spelt^oms  kept  under  water 
out  of  contact  of  air  till  they  have  evolved  gas, — ^peat-earth,  and  decayed 
wood  (fermenting  ^pe-juice  produces  no  effect).  These  substances  must 
be  used  in  the  moist  state.  If  they  come  into  immediate  contact  with 
detonating  ^as,  they  leave  the  hydrogen  unaltered,  and  merely  convert  a 
portion  of  the  oxygen  into  carbonic  acid.  If,  on  the  contrary,  they  are 
placed  beneath  a  layer  of  water  above  which  the  detonating  gas  is  confined, 
OT  if  they  are  tied  up  in  damp  linen  or  silk-gauze  and  suspended  in  the 
detonating  gas,  they  induce,  at  temperatures  near  22"^  (72°  %),  a  gradual 
condensation  of  that  gaa— or  of  a  mixture  of  four  measures  of  air  and  one 
of  hydrogen — and  consequent  formation  of  water.  At  the  same  time,  how- 
ever, part  of  the  oxygen  is  consumed  in  the  formation  of  carbonic  acid. 
Silk-stuff  thoroughly  boiled  in  water  and  wrapped  up  in  gauze  while  wet, 
does  not  begin  to  condense  detonating  gas  for  a  fortnight,  after  which 
interval,  its  decomposition  be/^ns ;  cotton  enclosed  in  muslin  acts  still 
more  slowly.  If  the  putrefaction  of  these  substances  be  prevented  by  the 
use  of  antiseptics — for  example,  if  peat- earth  be  moistened  with  solution 
of  common  salt, — ^the  power  of  condensing  detonating  gas  is  destroyed. 
The  above-mentioned  fermenting  substances  likewise  condense  detonating 
gas  mixed  with  three  times  its  volume  of  oxygen,  hydrogen,  nitrogen,  or 
nitrous  oxide  gas ;  and  in  the  case  of  the  last-mentioned  gas,  they  like- 
wise set  free  a  quantity  of  nitrogen.  One-fourth  of  a  volume  of  carbonic 
acid  gas  added  to  the  detonating  gas  prevents  the  condensation,  although 
carbonic  acid  introduced  into  pure  detonating  gas  by  the  fermentation  of 
the  organic  substances  has  no  such  effect.  A  mixture  of  1  volume  of  deto- 
nating gas  with  ^  of  carbonic  oxide  and  ^  of  defiant  gas  suffers  no  con- 


58  HTDROOBN. 

denaation ;  but  in  s  miztim  of  1  Yolutna  of  detonatiii^  g$B,  ^  of  a  rolumo 
of  olefiant  ga«>  and  ^  a  volnmo  of  marsh  gas,  condensation  takes  plaoe. 
Detonating  gas  formed  by  mixing  ozjgen  widi  hydrogen  produoed  from 
the  deoomposition  of  water  by  red-hot  iron  suffers  no  condensation  ;  and 
the  same  is  the  case  even  with  detonating  gas  in  which  the  hydrogen  thus 
obtained  is  mixed  in  the  proportion  of  1  to  4  with  hydrogen  produced 
by  the  action  of  sine.  It  appears,  then,  that  these  mixtures  behaye  with 
fermenting  substances  in  the  same  manner  as  with  platinum;  carbonic  acid 
alone  forms  an  exception,  probably  because  it  interferes  with  putrefaction. 
This  condensation  of  hydrogen  gas  by  bodies  in  a  state  of  fermentation 
explains  why  the  air  contains  no  hydrogen,  or  at  most  x^^nf  ^^  ^^  although 
this  gas  is  often  evolved  in  the  decomposition  of  organic  substances, 
and  the  action  of  lightning  does  not  appear  sufficient  to  effect  its  com- 
plete remoyal.  (Saussure,  If.  Bibk  univ.  IS,  880 ;  also  J,  pr.  Chm. 
14, 152.) 

tf .  Water  placed  in  contact  with  detonating  g^  at  ordinary  tempera- 
tures, brings  about  its  conversion  into  water,  in  the  course  of  a  few 
months,  possibly  because  the  oxygen  and  hydrogen  are  absorbed  by  the 
water,  and  thus  enabled  to  act  freely  on  one  another.  (Hooke  and  Orkney, 
OUb.  20,  143 ;  N.  W.  Fischer,  Seher.  Ann.  3,  123.)  Water  saturated 
with  oxygen  gas  takes  more  hydrogen,  and  water  saturated  with  hydrogen 
gas  takes  up  more  oxygen  than  ordinary  water.  (De  Marty.)— Saussure, 
on  the  contrary,  observed  no  diminution  of  volume  in  detonating  fas  left 
in  contact  with  water,  when  the  water  had  once  taken  up  as  much  deto* 
nating  gas  as  was  necessary  to  saturate  it  (5*25  measures  of  the  gas  to 
100  of  water). 

The  rapid  combination  of  oxygen  and  hydrogen  is  accompanied  by  a 
feeble  light  and  great  development  of  heat,  and  may  serve  to  produce 
extremely  high  temperatures.  When  one  of  the  gases  flows  into  the 
other,  merely  a  quiet,  pale,  reddish  flame  is  produwd  where  the  gases 
come  in  contact ;  but  when  they  have  been  previously  mixed,  the  combi- 
natiott  set  up  at  one  part  is  so  rapidly  communicated  to  the  rest,  in 
consequence  of  the  intimate  mixture  of  whi<^  gases  are  capable,  that  it 
appears  to  take  place  at  the  same  instant  throughout  the  entire  mass. 
A  violent  detonation  is  likewise  produced,  in  consequence  of  the  great 
elasticity  of  Jthe  intensely  white-hot  aoueous  yapour;  and  the  containing 
vessel,  unless  possessed  of  more  than  ordinary  strength,  is  broken  to  pieces. 

The  name  of  Lumen  pkiloiophicum  is  given  to  the  noiseless  flame  of 
hydrt^n  gas,  issuing  from  a  tube  into  the  air,  and  there  set  on  fire :  a 
glass  held  over  it  is  ouickly  covered  with  water. 

When  a  glass  bell-jar,  tube,  or  bulb,  open  at  bottom,  and  either  open 
or  closed  at  top,  is  held  over  the  lumsn  pkUotophieum^  a  continuous 
musical  note  is  frequently  heard.  This  is  the  Chemical  ffarmamcoj 
first  described  by  Lampadius  and  Mussin-Pouschkin.  This  sound,  which 
is  produced  even  when  the  tube  is  wrapped  round  with  a  cloth,  and 
likewise  above  100%  at  temperatures  therefore  at  which  the  water 
formed  is  in  the  state  of  vapouiv-^also,  though  not  so  strongly,  by  other 
combustible  gases,  vis.  caruonic  oxide,  olefiant  sas,  marsh-gas,  snlphu* 
retted  hydrogen,  arseniuretted  hydrogen,  and  the  vapours  of  alcohol 
and  ether— is  attributed  by  Faraday  (Ann,  Ckhn,  Pkp9.  8,  363)  to 
this  circumstance,  that  a  strong  current  of  air  is  established  within  the 
tube  (by  which  in  fact  the  flame  is  eloa^^ated),  and  that  small  portions  of  air 
are  thereby  mixed  with  the  hydrogen  in  sndi  a  manner,  as  to  form  small 


FORMATION  OP  WATER.  59 

quantities  of  detonfttiog  gaa,  whioh  when  set  on  fire  produoes  slight 
explosions  succeeding  each  other  qniokly  and  regnlarlj. 

If  a  tuhnlated  glass  jar  be  filled  ander  water  with  hydrogen  gas,  the 
tabulure  opened,  and  the  gas  set  on  fire  there,  it  bums  with  a  faint  quiet 
flame ;  but  on  lifting  the  jar  out  of  the  water,  a  flame  8  inches  high  is 
produced,  and  is  finally  extinguished  with  a  sliffht  detonation,  because 
the  air  which  enters  at  the  bottom  becomes  mixed  with  the  last  .portions 
of  hydrogen,  and  forms  a  detonating  mixtnro.  (Beraelius,  Lehrb,  1, 
195.) 

A  mixture  of  8  yolumes  of  hydrogen  gas  and  5  rolumes  of  atmo^ 
spheric  air,  produces  a  moderate  detonation  when  set  on  fire,  and  bursts 
vessels  which  are  not  very  strong.  On  filling  an  ordinary  phial  three 
parts  full  of  hydrogen,  and  letting  the  rest  of  the  water  run  out,  so  that 
the  quantity  of  air  introduced  may  not  be  suflScient  for  the  complete 
combustion  of  the  hydrogen,  then  holding  the  phial  with  its  mouth  down- 
wards  and  settiuff  fire  to  the  contents,  the  combustion  takes  place  slowly, 
proceeding  from  below  upwards;  and  with  a  suitable  form  of  the  bottle, 
and  a  proper  proportion  of  the  mixed  gases,  a  sound  is  produced  similar 
to  that  of  the  chemical  harmonica.    (Geiger.) 

Detonating  ga9f  or  a  mixture  of  2  rolumes  of  hydrogen  and  1  of 
oxygen,  produces,  when  soap-bubbles,  &c.,  filled  with  it  are  infiamed,  an 
explosion  more  violent  than  that  produced  by  any  other  gaseous  mixture, 
and  when  exploded  in  the  Air-piaioly  propels  the  cork  with  immense 
force.  If  a  pitch-bladder  be  blown  with  detonating  gas  to  the  capacity 
of  20  or  30  cubic  inches  by  means  of  a  common  day-pipe,  then  let  faU 
from  the  pipe  on  a  plate  strewed  with  lycopodium,  and  from  this  slipped 
on  to  the  left  hand,  it  may  be  set  on  fire  with  the  rieht  hand,  without 
shattering  or  in  any  way  injuring  the  hand  by  the  explosion  ;  it  should, 
however,  be  held  at  some  distance  £rom  the  body.  (Bottger,  Ann. 
Pharm.  33,  348.)  When  set  on  fire  in  a  confined  space,  as,  for  instance, 
by  the  electric  spark  in  VoUa^$  JSudiometery  detonating  gas  bums  with- 
out noise,  and  with  a  sudden  flash :  if  the  gases  are  contained  in  a  strong 
glass  globe,  a  dassling  light  is  produced  (p.  30).  A  vessel  is  more 
easily  shattered  by  the  explosion  of  detonating  gas,  when  the  gas  is  set 
on  fire  in  the  middle,  than  when  the  combustion  is  made  to  commence 
near  the  stoppered  opening.     (Ddbeieiner,  Scku.  63,  164.) 

In  Newman*  and  Clarhe*$  Oxp-kydrogen  Blowpipe,  detonating  gas, 
or  a  mixture  of  9  measures  of  hydrogen  and  4  of  oxygen,  is  condei^ed 
to  the  amount  of  several  atmospheres  in  a  metallic  reservoir,  and  made  to 
flow  from  this  through  a  narrow  tube,  at  the  end  of  which  it  is  burnt. 
The  flame  bums  with  a  feeble  light,  but  excites  the  most  intense  heat 
yet  produced  by  any  means  whatever.  According  to  Clarke,  a  mixture 
of  4  volumes  of  oxygen  and  9  of  hydrogen  produces  the  strongest  heat, 
stronger  than  that  obtained  by  the  combustion  of  a  mixture  dF  oxygen 
with  coal  gas  or  oleflant  gas.  Pfaff  recommends  a  mixture  of  1  volume 
of  oxygen  and  2^  of  defiant  gas,  or  of  oxygen  and  coal-gas;  which,  he 
says»  gives  at  least  as  much  heat  as  oxygen  and  hydrogen.  If  the  con- 
densation in  the  reservoir  amounts  to  10  atinos^heres,  the  gas  no  longer 
takes  fire  with  facility,  probably  because  it  is  too  much  cooled  by 
expansion  as  it  flows  out.  (Parrot.)  The  communication  of  the  flame 
to  the  gas  in  the  reservoir  taxes  place  with  so  much  the  less  facility,  as 
the  gas  Issues  with  greater  rapidity,  and  the  tnbe  has  less  width  and 
greaW  eoeling  power  (pw  34).  Bui  since  in  an  experiment  of  some 
doratien,  the  tnbe  beceiMa  eonttauallj  hotter,  and  the  vdociiy  of  efllnz 


60  HYDROGEN. 

of  the  f^  continually  diminisbes^  there  is  considerable  danger  of  the 
flame  nltimately  passing  into  the  receiver,  causing  an  explosion  which 
may  probably  be  attended  with  fatal  consequences.  This  acci- 
dent may  be  prevented,  either  by  oil  or  water  valves,  or,  according 
to  the  plan  of  Hemming  and  Bischof,  by  interposing  between  the  reser- 
voir and  jet  a  brass  tube,  6  inches  long  and  f  of  an  inch  wide,  filled 
with  veiy  fine  wires  of  equal  length  placed  longitudinally,  and  forcibly 
pressed  together  by  means  of  a  strong  conical  wire  rammed  down  the 
middle ;  so  that  the  channels  for  the  gas  are  made  very  narrow,  and 
efifectually  prevent  the  recession  of  the  flame,  however  slowly  the  gas 
may  issue.  This  backward  communication  of  the  flame  is,  according  to 
Pfaff,  easiest  with  hydrogen  gas,  less  easy  with  defiant  gas,  and  least  of 
all  with  coal  gas. 

The  apparatus  invented  by  Hare,  in  which  the  gases  are  contained 
in  separate  vessels,  and  only  brought  together  just  before  they  are  burned, 
is  free  from  danger,  but  less  powerful  than  the  preceding.  The  gases,  as 
they  issue  from  the  two  reservoirs,  are  either  made  to  enter  a  common 
tube,  (which  may  be  filled  with  wire,  according  to  Hemming*s  plan,)  and 
from  this  by  a  fine  jet  into  the  air,  where  they  are  burned  (Hare); 
or  the  oxygen  gas  passes  into  the  air  through  a  narrow  tube,  surrounded 
by  a  brass  cylinder,  of  a  diameter  rather  greater  than  its  own  ;  and  the 
hydrogen  gas  passes  through  the  narrow  space  between  the  inner  and 
outer  tube  (Daniell) ;  or  the  two  tubes  by  which  the  gases  are  conducted 
are  placed  nearly  parallel  with  each  other,  at  an  angle  of  5°,  and  deliver 
the  gases  by  two  apertures  situated  -^  of  an  inch  apart.  (Rutter.)  In 
all  these  cases,  the  stopcocks  of  the  reservoirs  containing  the  oxygen  and 
hydrogen  must  be  so  adjusted  that  the  gases  may  be  delivered  in  the 
right  proportion.  If  the  flame  should  appear  too  large  in  consequence  of 
an  excess  of  hydrogen,  the  flow  of  that  gas  must  be  restricted  till  the 
flame  just  begins  to  contract. 

The  flame  of  the  oxy-hydrogen  blowpipe  is  veiy  pale  in  itself,  but 
difi'uses  a  dazzling  light  as  soon  as  any  solid  body  is  introduced  into  it. 
When  the  jet  of  gas,  after  being  set  on  fire,  is  directed  under  water,  it 
continues  to  bum  below  the  surface  of  the  liquid,  in  the  form  of  a  globe, 
and  fuses  and  burns  wires  held  in  it. 

In  order  to  show  that  the  water  produced  by  the  combination  of 
oxygen  and  hydrogen  gases  weighs  exactly  as  much  as  the  sum  of  the 
quantities  of  the  two  gases  consumed.  Cavendish,  Lavoisier,  Monge, 
Fortin,  Fourcroy,  Vauquelin,  Seguin,  and  others  contrived  the  Gasom^r, 
an  apparatus  in  which  hydrogen  gas  is  made  to  flow  into  a  glass  globe 
filled  with  oxygen,  and  there  set  on  fire,  and  the  combustion  kept  up  by 
constant  renewal  of  the  two  gases.  In  Dobereiner*s  Spongy  Platinum 
Gasometer  (Schw,  42,  62),  a  glass  globe  containing  spongy  platinum  is 
exhausted  of  air,  and  detonating  gas  contained  in  a  reservoir  allowed  to 
enter  in  small  quantities  at  a  time,  by  proper  regulation  of  the  stopcocks : 
a  quantity  of  water  is  thus  formed  in  the  globe. 

Water  produced  by  the  combustion  of  hydrogen  gas  contains  nitric 
acid,  if  the  gas  consumed  contains  nitrogen  ;  and  likewise  (according  to 
Saussure,  Ann.  Chim.  71,  282)  ammonia,  if  the  hydrogen  is  in  excess. 

Freparaiian  of  Pure  Water.  Rain  or  snow-water  (especially  the 
latter)  collected  in  clean  vessels  is  pure,  with  the  exception  of  a  small 
quantity  of  air.  The  water  which  falls  at  the  beginning  of  a  shower 
may  contain  dust  previously  diffused  through  the  atmosphere^  but  not 


WATEIL  61 

tbat  which  fidls  afterwards.  Rain  or  snow-water  collected  in  the 
neighbourhood  of  the  sea,  may  also  contain  hydrochloric  acid.  The 
assertion  of  Hassenfratz  {J,  de  VEcoL  polyt.  Cah.  4,  570),  that  snow- 
water is  richer  in  oxygen  than  water  from  other  sources,  has  been 
disproved  by  Fabroni. 

Careful  distillation  of  spring  or  rain-water  in  metallic  vessels  (it  is 
best  to  use  a  copper  boiler  with  a  head  and  condensing  tube  of  copper  or 
silver)  purifies  the  water  from  fixed  saline  or  earthy  matters,  which  it 
may  contain :  Distilled  Water,  When  the  head  and  condensing  tube  are 
made  of  copper  or  tin,  a  small  quantity  of  metal  may  be  introduced  into 
the  water,  if  the  apparatus  has  been  previously  used  to  distil  an  acid 
liquid.  If  the  copper  is  soldered  with  lead,  pure  water  itself  will  form 
oxide  of  lead  with  it.  From  glass  vessels  water  extracts  alkali,  common 
salt,  &c.  From  water  containing  hydrochlorate  of  magnesia  in  solution, 
hydrochloric  acid  may  distil  over,  unless  the  boiler  likewise  contains 
hydrate  of  lime,  which  may  also  serve  to  retain  the  carbonic  acid  of  the 
water.  If,  however,  the  water  contains  any  ammoniacal  salt,  this  may 
be  decomposed  by  the  lime,  and  then  the  distilled  water  will  be  contami- 
nated with  ammonia,  and  will  require  a  second  distillation  with  a  small 
quantity  of  sulphuric  acid  to  retain  the  ammonia.  Sulphuric  acid  is  also 
useful  when  the  water  contains  any  volatile  salt  of  ammonia,  the  carbo- 
nate, for  instance. 

The  only  mode  of  freeing  water  from  the  greater  part  of  the  air, 
that  is  to  say,  the  oxygen,  nitrogen,  and  carbonic  acid,  which  it  contains, 
is  by  long  continued  boiling:  Thoroughly  boiled  Water,  Water  thus 
treated  must,  while  yet  boiling  hot,  be  passed,  without  coming  into 
contact  with  the  air,  into  vessels  standing  over  mercury  :  this  is  the  only 
way  of  preventing  it  from  again  becoming  saturated  with  air. 

Properties.  Water  solidifies  in  the  form  of  ice  between  0°  and— 10°  C. 
(32°  and  14°  F.)  Ice  belongs  to  the  six-membered  or  hexagonal  crys- 
talline system.  Double  six-sided  pyramid  (Fig.  131),  r:  7**= 80°;  six- 
sided  pnsm,  often  shortened  into  a  tabular  form  (Fig.  135);  the  same 
with  its  ed^es  removed  (Fig.  137);  triangular  prism;  rhombic  prism, 
(Fig.  61),  1?:  tt=:120°.  (Smithsou,  Ann.  Phil.  5,  340;  Hericart  de 
Thury  and  Clarke,  Ann.  Chim.  Phys.  21,  156;  Hessel,  Kastn.  Arch. 
10,  299.)  Ice  has  but  one  axis  of  double  refraction,  and  this  axis 
is  perpendicular  to  the  plates  of  ice  as  they  form;  sometimes  the 
plates  have  rhombohedral  summits  projecting  from  them.  (Brewster, 
Phil.  Mag.  J.  4,  245;  also  Pogg,  32,  329.)  Hailstones  also  are  some- 
times crystalline.  (Grotthuss,  Scher.  Ann.  2,  1 35.)  Snow  exhibits  the 
form  of  regular  hexagonal  tables ;  frequently  six  of  these  tables,  more  or 
less  elongated,  are  united  in  the  form  of  a  star.  In  the  crystals  of  ice 
formed  on  windows,  the  primary  form  is  often  a  six-sided  prism  of  some- 
what greater  thickness.  (Marx.  Schw.  54,  426.)  The  specific  gravity 
of  ice  is  0'950,  according  to  Le  Royer  &  Dumas;  09268,  according  to 
Osann  {Kastn.  Arch.  19,  95^;  0*9180,  according  to  Brunner;  and  0*9184, 
according  to  Playfftir  &  Joule.  Ice  is  colourless  and  transparent,  a 
slow  conductor  of  heat,  a  non-conductor  of  electricity,  and  becomes 
electric  by  friction. 

Ice  melts  and  is  converted  into  water  at  temperatures  above  0°  C, 
0°  R.,  or  +  32°F.  The  specific  gravity  of  water  is  1-000.  One  Paris 
cubic  foot  of  water  at  8°  C.  weighs  70  pounds,  223  grains,  old  French 
weight;  or,  1  cubic  decimetre  (litre),  at  4-44'  C.  weighs  18827*15  grains. 


62  HTDROOEN. 

paids  de  matv,  or  1000  grammes  (Loferre-Gi&Ma);  1  Rhenish  eubie  foot 
at  20""  C.  weighs  64*963  Cologne  pounds  (Schmidt);  1  English  oabie 
foot  at  13*2'' C.  or  55*8'' F.  weighs  99874  ounces  avoirdupoii.  (Robt- 
son.)  1  English  cubic  inch  at  15'$''  C.  or  60""  F.  weighs  252*506  ^ins, 
(Shuckbnrgh,  Sekw,  11,  59.)  1  cubic  centimetre  at  4*  O.  weighs  1 
fftarome.  {Comp.  Weher,  Fogg.  18,608,  Ku^ffer,  J.  pr.  Ckem,y  22,  62.) 
Tables  of  the  density  of  water  at  different  temperatures  have  been 
constructed  by  Hftllstrom  {Ann.  Ohim,  Fhy».,  28,  56),  and  by  Mar- 
kiewis,  (Pogg.  19, 135).  HSee  also  Kopp*s  Table,  Vol.  L,  p.  231.1 
Water  is  at  its  maximum  density  at  a  temperature  of  4°  C.  (I.|  225.) 
Water  is  slightly  compressible,  but  only  under  very  great  pressori. 
Accoiding  to  Perkins  (Oilh,  72,  173;  Ann.  FhU.  17>  135,  and  222; 
Pogg*  9,  554),  the  compression  produced  by  a  pressure  of  826  atmo* 
spheres  amounts  to  0*035,  therefore  by  1  atmosphere,  to  0*000108;  by 
2000  atmospheres,  to  ^\  according  to  Oerstedt  {Ann.  FhU.  20,  236; 
Sckw.  86,  332;  52,  9;  Ann,  Chvm.  Fhys.  22,  192;  Fogg.  9,  603), 
the  compression  produced  by  one  atmosphere  amounts  to  0*000045 ;  and 
up  to  70  atmospheres,  the  compressibility  increases  in  direct  proportiott 
to  the  compressing  power;  according  to  Canton,  a  pressure  of  one 
atmosphere  produces  a  compression  of  0*000044.  {Compare  also  Pfafl^ 
O'dh.  72,  161;  CoILmIou  &  Sturm,  Ann.  Chim.  Phy$.  35,  113;  also 
Pogg.  12,  39,  and  161.)  The  sudden  compression  of  water  is  accom- 
panled  by  a  flash  of  light. 

Water  boils — ^when  the  barometer  stands  at  28  Paris  inches,  or  29*8 
English  inches— at  100''  C,  80''  R.,  212''  F.,  O""  D.,  and  when  converted 
into  rapour,  takes  np  1,700  times  the  space  which  it  occupies  when 
liquid.  [For  the  refractive  power,  tension,  specific  gravity,  and  latent 
heat  of  aqueons  vapour,  see  Vol.  I«,  pp.  95,  262,  263,  279,  283,  285.] 
Water  is  tasteless  and  inodorous. 

CalcoUticm.  Dumas.     Ben.  &  Dulong.  Vol.        Sp.  gr. 

H  ....  1  11-11  IMl  IM  Hydrogen  6m    1  ....  0069S 

O  ..   8  88-88  88-88  88*9  Oxygen Gta ....  0'5  .,..  0*ft»46 

HO .  9  100-00  100-00  1000  Vapourof Water  1      ....  0*6239 

(H*0  B  2  .  6-2398  +  100  «•  112-48.    Beneliua.) 

Decontpodtiona.  1.  By  electricity,  into  oxygen  and  hydrogen  gases. 
(I.,  446—455.) 

2.  The  alkali-metals  at  ordinary  temperatures-carbon,  the  metals  of 
the  earths,  and  likewise  molvbdenum,  chromium,  uranium,  manganese, 
zinc,  tin,  cadmium,  iron,  cobalt,  and  nickel,  at  a  low  red  heat— «nd 
antimony,  bismuth,  lead,  and  copper,  at  a  strong  red  heat — ^take  np  tha 
oxygen  of  water  and  liberate  the  hydrogen  in  the  form  of  sas.  In 
presence  of  various  acids,  this  decomposition  of  water  is  effected  at  ordi* 
nary  temperatures,  or  a  little  above,  by  most  of  the  earth-metals,  as  well 
as  by  manganese,  sine,  cadmium,  tin,  iron,  oobalt,  and  nickel. 

3.  Chlorine,  under  the  influence  of  light,  or  at  a  red  heat,  combines 
with  the  hydrogen  of  water,  and  liberates  the  oxygen  in  the  form  of  gas. 

4.  Both  constituents  of  water  enter  into  new  combinations,  when  tho 
water  is  brought  in  contact  with  phosphorus,  chloride  of  phosphorus, 
phosphide  of  potassium,  &c. 

Combinations.    A.  De/iniU  Oompoundi,  Hydrates  .--^ 
a.     With  Simple  Svhstances.   The  hydrates  of  chlorine  and  bromine, 
containing  10  atoms  of  water. 


WATBR.  63 

b»  WUh  Acids,  m.  The  hydrain  qf  the  oxygsn^ofiids  generally  oon- 
tain  aa  many  atoms  of  water  as  their  normal  salts  contain  atoms  of  base; 
the  water  in  these  hydrates  plays  the  part  of  a  base,  and  must  be  regarded 
as  Batie  Water  or  Water  of  Hydration.  Most  of  the  acid  hydrates  are 
solid ;  those  of  sulphuric  and  nitric  aoid,  liquid ;  the  solid  hydrates  of 
this  class  melt  on  the  application  of  heat,  provided  they  do  not  decompose. 
The  combination,  which  is  often  attended  with  considerable  development 
of  heat,  is  very  intimate,  so  that  most  of  these  hydrates  rather  evaporate 
unaltered  than  part  with  their  water.  To  this  class  belong,  e.  g,  the 
hydrate  of  sulphuric  acid^  or  oil  of  vitriol  (HO,  SO');  the  hydrates  of  the 
three  phosphoric  acids  (HO,  aP0»,-.2H0,  6P0*,  -  3H0,  cPO*).  To 
detect  and  estimate  the  water  in  hydrates  of  this  description,  they  are 
heated  in  contact  with  a  known  weight  of  oxide  of  lead,  lime,  kc,  in 
excess;  these  substances  retain  the  acid,  and  allow  the  water  to  escape. 

^.  0xygen-acid8  containing  Water  of  Cryetalligation,  Many  acids 
combine  with  a  larger  quantity  of  water  than  is  necessary  for  the  forma- 
tion of  hydrates,  and  form  OTystalline  compounds  in  which  one  part  of 
the  water  exists  as  Basic  Water,  the  rest,  in  a  state  of  less  intimate 
combination,  as  Water  of  CrystaUiaation  or  Ice  of  Cryitalligation.  Crystal- 
lised sulphuric  acid  is  SO',  2H0,  or  more  correctly,  perhaps,  HO,  SO' + HO, 
that  is  to  say,  a  compound  of  the  hydrate  witu  water  of  crystallization. 
On  the  application  of  heat,  the  water  of  crystallization  evaporates  first, 
then  the  undecomposed  hydrate.  Besides  the  hydrate  and  the  crystal- 
liied  acid,  sulphuric  acid  likewise  forms  other  definite  compounds  with 
water. 

c.  With  Salifiable  Bases.  ».  The  hydrates  of  the  Salifiable  Bases  gene- 
rally contain  a  number  of  atoms  of  water  equal  to  the  number  of  atoms 
of  acid  required  to  form  a  normal  salt,  so  that  the  water  in  these  com« 
pounds  plays  the  part  of  an  acid.  All  hydrates  of  bases  are  solid,  and 
fusible  at  a  red  heat,  provided,  they  are  not  decomposed.  These  combi- 
nations also  are  very  intimate;  their  formation  is  sometimes  accompanied 
by  development  of  light  and  heat;  and  many  of  them  are  undecomposible 
at  a  red  heat.  The  combination  of  water  with  barfta  and  lime  is 
attended  with  great  development  of  heat;  hydrate  of  lime  (CaO,HO) 
parts  with  its  water  at  a  red  heat;  hydrate  of  baryta  ^BaO,HO)  remains 
undecomposed  even  at  a  strong  red  heat;  hydrate  oi  potassa,  or  lapis 
causticus  (KO,HO),  vaporizes  undecomposed  at  a  red  heat.  To  determine 
the  water  in  these  compounds,  they  are  heated  to  redness  in  contact  with 
a  weighed  quantity  of  ignited  silicic  or  boraoio  acid  in  excess,  which 
drives  out  the  water. 

0,  SaJjdaUe  Bases  containing  Water  of  Crystallisation,  From  the 
aqueous  solution  of  several  alkalis,  compounds  are  separated  which^ 
beJBides  water  of  hydration,  likewise  contain  a  definite  quantity  of  less 
intimately  combined  water,  or  water  of  crystallisation*  These  crystals 
fuse  at  a  gentle  heat,  evolve  the  water  of  crystallisation,  and  leave  the 
hydrate  behind.  Crystals  of  potassa  are  composed  of  K0,5H0  or 
K0,H0  +  4H0;  crystals  of  baryta,  of  BaO,9HO,  or  BaO,HO  +  8HO. 

d.  With  Simple  and  Double  Salts.  These  compound^  which,  accord- 
ing to  the  nature  of  the  salts  and  to  external  circumstances,  may  contun 
from  I  to  24  atoms  of  water  to  each  atom  of  salt,  are  produced: 
1.  When  the  powdered  anhydrous  salt  is  mixed  with  the  requisite  quan- 
tity of  water.  The  moist  paste,  which  is  a  mechanical  mixture  of  the 
salt  and  water,  hardens  to  a  dry  solid  body  as  the  water  passes  into  the 
state  of  chemical  oombination,  the  change  being  often  accompanied  bj 


61  HYDROGEN. 

perceptible  rise  of  temperatare.  Anhydrous  gypsnm  mixed  with  water 
forms  a  solid  mass;  anhydrous  Olaaber's  salt  becomes  moderately  heated 
when  mixed  with  water ;  in  the  case  of  anhydrous  sulphate  of  copper, 
the  temperature  rises,  according  to  Graham,  to  ISS"^. — 2.  When  the 
anhydrous  salts,  in  the  state  of  powder,  are  exposed  to  the  air  for  a  con- 
siderable time,  they  for  the  most  part  take  from  it  their  full  amount  of 
water  of  crystallization.  Ignited  carbonate  of  soda  placed  in  a  moist 
atmosphere  recovers  the  whole  of  its  10  atoms  of  water  (Hugh  Watson, 
Fkil.  Mag.  J.,  12,  ISO);  sulphate  of  magnesia  and  sulphate  of  zinc  take 
up  7  atoms  of  water;  sulphate  of  nickel,  6  atoms;  pyrophosphate  of  soda 
(2NaO,6PO),  10  atoms;  but  anhydrous  Glauber's  salt  takes  up  no  water 
from  the  air  (Bliicher,  Fogg.  50,  541). — 3.  When  the  salts  are  suf- 
fered to  crystallize  from  their  aqueous  solutions.  The  same  salt  may 
— ^according  to  the  temperature  and  concentration  of  the  solution— <5ry»- 
tallize  either  with  or  without  water,  and  in  the  former  case  with  a  greater 
or  smaller  number  of  atoms  of  water.  The  hotter  and  more  concentrated 
the  solution,  the  less  inclination  has  the  salt  to  take  up  water;  on  the 
other  hand,  the  colder  and  more  dilute  the  solution,  the  greater  is  the 
quantity  of  water  which  the  crystals  take  up.  Addition  of  oil  of  vitriol 
to  the  solution  of  the  salt  may  likewise  cause  it  to  crystallize  in  the 
anhydrous  state,  or  with  a  smaller  qnantity  of  water  than  otherwise. 
But  with  the  different  quantities  of  water,  which  vary,  not  by  a  gradual 
transition,  but  according  to  determinate  numbers  of  atoms,  the  crystalline 
form  and  other  properties  likewise  vary :  thus,  the  hardness  and  density 
of  a  salt  diminish  as  its  quantity  of  water  increases.  Nitrate  of  strontia 
crystallizes  in  regular  octohedrons  not  containing  water,  when  its  aqueous 
solution  is  evaporated  at  a  high  temperature;  but  when  a  more  dilute 
solution  is  left  to  evaporate  in  the  cold,  the  salt  crystallizes  in  oblique 
rhombic  prisms  containing  5  atoms  of  water.  Solution  of  borax  evapo- 
rated at  a  high  temperature  yields  regular  octohedrons  with  5  atoms  of 
water ;  but  when  crystallized  in  the  cold,  it  yields  oblique  rhombic  jprisms 
with  10  atoms  of  water  of  crystallization.  The  water  of  crystallization 
of  salts  must  be  carefully  distinguished  from  their  water  of  decrepitation 
(I.,  14) :  the  former  exists  in  crystals  according  to  a  definite  number  of 
atoms,  and  with  it  the  crystalline  form  and  other  properties  are  essentially 
connected;  the  latter  is  accidentally  enclosed  in  the  crystals  in  irregularly 
varying  quantities;  and  the  salt  retains  the  same  form,  whether  the 
quantity  of  water  thus  enclosed  is  great  or  small. 

Salts  containing  water  of  crystallization  lose  it:  1.  By  heating. 
Most  hydrated  salts,  especially  those  which  contain  large  quantities  of 
water,  dissolve  in  their  water  of  crystallization  either  wholly  or  in  greater 
part  when  strongly  heated;  they  pass  into  the  state  of  Aqueoui  Pusion. 
The  water  then  evaporates  with  ebullition,  and  brings  the  salt,  if  it  be 
viscid,  into  a  spongy  state  (borax,  alum).  Many  salts  thus  de-hydrated 
melt  again  at  a  red  heat ;  and  with  regard  to  these,  the  Igneous  Fusion 
thus  produced  must  be  distinguished  from  the  aqueous  fusion.  Other 
salts  which  contain  less  water,  or  are  less  soluble  in  it  (bicarbonate  of 
potassa,  gypsum),  are  converted  by  heat  into  an  opaque,  friable  mass, 
made  up  of  the  particles  of  the  dry  salt  and  the  interstices  previously 
filled  with  the  water  of  crystallization — ^the  change  proceeoling  from 
without  inwards,  and  not  causing  any  alteration  in  the  external  shape  of 
the  salt.     But  few  hydrated  salts  decrepitate  when  heated  (I.,  14). 

2.  Efflorescent  Salts  part  with  their  water,  even  at  ordinary  tempera- 
tures, when  placed  in  air  of  a  certain  degree  of  dryness,  and  are  thereby 


WATER.  65 

bronght  into  the  opaque  friable  condition  jost  described.  In  this  process, 
the  affioity  between  tne  salt  and  the  water  is  overcome  bj  the  affinity  of 
heat  for  water,  and  by  the  adhesion  of  the  air  to  vapour  of  water.  The 
latter  force  is  greater  in  proportion  as  the  quantity  of  aqueous  vapour 
already  present  in  the  air  is  less.  The  more  strongly  therefore  the  salt 
retains  its  water  of  crystallization,  the  dryer  must  the  air  be  to  cause  it 
to  effloresce.  Hence,  according  to  A.  Vogel  (Schw,  22,  1 60),  crystallized 
sulphate  of  copper,  which  remains  unaltered  in  air  in  its  ordinary  state, 
effloresces  rapidly  in  a  space  filled  with  air,  in  which  oil  of  vitriol,  lime, 
chloride  of  calcium,  or  some  other  substance  having  a  strong  attraction 
for  water  is  placed ;  because,  by  this  means,  the  air  is  continually  kept  in 
a  state  of  perfect  dryness.  Still  more  rapidly  does  the  efflorescence  take 
place  in  a  space  devoid  of  air,  and  containing  some  such  substance  which 
absorbs  vapour  of  water  with  rapidity ;  because,  by  this  absorption  of  the 
vapour  as  fast  as  it  is  formed,  the  pressure  which  that  vapour  would  by 
its  tension  exert  on  the  water  still  contained  in  the  crystal  is  removed. 
When  the  temperature  of  the  air  is  between  6^  and  12°  (42 '8°  and 
53*6®  F.),  and  the  dew-point  (i.  e.  the  temperature  at  which  the  aqueous 
vapour  in  the  air  would  condense)  3"  or  4**  (37 '4**  or  39*2°  F.)  below  this 
temperature,  carbonate  of  soda  with  lO^^ms  of  water  does  not  effloresce. 
In  air  whose  temperature  is  14*4°  (^v1  ^')>  G^lauber's  salt  effloresces 
when  the  dew-point  is  at  9*4*^  (48*9°  F^  and  carbonate  of  soda  when  it  is 
at  8-9°  (48°  F.).  In  air  at  14*4°,  with  the  dew-point  above  10°,  Glauber's 
salt  does  not  effloresce.  (Hugh  Wattson,  Phil.  Mag. ,/.  12,  1 30.)  Many 
salts  effloresce  only  when  their  surface  is  injured,  the  efflorescence  then 
commencing  at  the  place  at  which  the  scratch  is  situated:  carbonate, 
phosphate,  and  sulphate  of  soda  may,  when  uninjured,  be  kept  for  years 
in  an  open  dish  without  efflorescing.     (Faraday,  Pogg,  33,  186.) 

3.  Immersion  of  the  hydrated  crystals  in  liquids  which  do  not  dissolve 
the  salt  but  attract  the  water,  brin^  them  into  the  opaque  effloresced 
condition ;  e.g.  protosulphate  of  iron  immersed  in  oil  of  vitriol  or  in  alcohol. 

When  a  salt  contains  several  atoms  of  water  of  crystallization,  it 
sometimes  happens  that  one  atom  is  retained  with  much  greater  force 
than  the  rest  This  more  intimately  combined  water  is  distinguished 
by  Graham,  under  the  name  of  ComtUuUonal  Water.  Sulphate  of  mag- 
nesia ^MgO,SO'-f7Aq)  loses  6  atoms  of  water  at  132°,  but  the  sevenSi 
not  below  238°.  It  is  probable  that  sulphate  of  magnesia  forms  a  crys- 
talline  compound  with  1  atom  of  water,  and  consequently,  that  this  con* 
stitutional  water  is  to  be  regarded  merely  as  more  intimately  combined 
water  of  crystallization;  just  as  the  5  atoms  of  water  in  octohedral  borax 
are  in  a  state  of  more  intimate  combination  than  the  other  5  atoms  like- 
wise present  in  ordinary  borax.     (6m.) 

[Definite  campoufids  of  water  tnth  organic  8ub9tQ,nces  will  be  described 
under  the  head  of  Organic  Chemistry.'] 

B.  Compounds  in  variable  proportion^  containing  excess  of  footer. 
Aqueous  solutions.  Water  takes  up  several  elementary  substances,  as 
iodine,  bromine,  and  chlorine,  also  the  greater  number  of  acids,  the 
alkalis,  many  salts,  both  simple  and  double,  and  many  organic  compounds, 
into  itself, — forming  solutions  which  are  concentrated  or  dilute,  according 
to  the  relative  proportions  of  the  water  and  the  substance  dissolved. 
Aqueous  solutions  may  be  divided  into  those  in  which  the  dissolved 
substance  is  gaseous,  and  those  in  which  it  is  either  liquid  or  solid. 

a.  Water  absorbs  all  Oases.  Of  some  it  absorbs  a  volume  about  equal 
to  its  own;  of  others  less;  of  others,  again,  a  much  greater  volume. 

TOL,  II.  F 


66 


HTDROOBN. 


Volunui  ofd%f€r4fU  Gam  ahiorh^d  by  1  76hm4  of  WaUr, 

Name  of  Gat. 

Dalton. 

W.Henry. 

"Saossure. 

D.yy. 

Terfluoride  of  boron    ... 
Ammonia                

20 

about  2 

1 

1 

1 
0125 
0125 
0-037 
0-037 
0037 
0-025 
0-0156 
0020 

108 

108 
0-86 

00214 

1-014 

0037 

0050 

00153 

0*0201 

O-0H51 

43-78 

2-53 

1-06 
0.76 
0-155 

0*065 

0-042 
0062 
0046 

670 
480 

30 

0-54 
0025 

010 
0-02 

700.  J.  Davy. 
780.  Thomson. 

Hydrochloric  acid    

Terfluoride  of  silidum... 
Sulphurous  acid  

516.  lliomson. 
263.  J.  DaTy. 
33.  Thomson. 

Oxide  of  chlorine    

Cyanogen     

aboYe  7.  Stadion. 
4-5.  Gay.Lusaac. 

Chlorine  

Hydroselenic  acid    

Hydrosulphuric  add    .... 
Carbonic  add  

above  3.  Berzelius. 

f  3.  Gay-Lussae  & 

1      Thenard. 
116.  CftTendish. 

Nitrous  oxide  

Olefiantgas 

Phosphuretted  hydrogen 
Marsh-Kas    

0*018.  Gengembre. 

Oxygen    

Nitric  oxide 

Nitrogen 

Carbonic  oxide    

Hydrogen     

Id  performing  these  experiments,  it  ia  of  the  utmost  importance  to  free 
the  water  completely  from  air  hj  long-continned  boiling  (p.  G I ) ;  beoanse 
the  gre  iter  the  quantity  of  any  other  gas  previously  oontained  in  the 
water,  the  leas  will  it  take  up  of  the  gas  which  is  the  subject  of  experi- 
ment ;  the  gas  must  also  be  perfectly  pure  and  in  excess. 

Gases  which  may  be  liquefied  by  strong  pressure  (I.,  285)  are  mors 
abundantly  absorbed  by  water  than  those  which  are  not  condensable ;  the 
condensability,  however,  is  not  always  proportional  to  the  capacity  of 
absorption ;  thus,  hydrochloric  acid  is  more  difficult  to  condense,  but  much 
more  readily  absorbed  than  sulphurous  acid.  The  chemical  attraction 
between  the  water  and  the  ponderable  base  of  the  gas  is  therefore  an  ele- 
ment in  the  determination  of  the  result. 

Whatever  may  be  the  external  pressure  to  which  a  gas  slightly  absorh* 
able  by  water  is  subjected,  the  water  always  takes  up  the  same  volume 
of  it  at  the  same  temperature;  consequently,  the  weight  of  gas  absorbed 
will  be  twice  as  great  under  a  pressure  of  two  atmospheres,  and  only  half 
aiS  great  under  a  pressure  of  half  an  atmosphere,  as  it  would  be  under  the 
ordinary  atmospheric  pressure.  (W.  Henry.)  This  law  is  only  approxi- 
mately true :  under  a  pressure  of  7  atmospheres,  water  absorbs  only  5 
times  as  much  carbonic  acid  gas  as  it  does  under  a  pressure  of  one  atmo- 
sphere. (Couerbe,  J.  Pharm.  20,  121.)  With  gases  of  which  water 
absorbs  more  than  one  volume,  the  variation  of  solubility  consequent 
upon  inerease  or  diminution  of  external  pressure  is  not  nearly  so  great. 
Increase  or  diminution  of  temperature,  by  which  the  volume  of  the  gas  is 
expanded  or  contracted,  produces  the  same  effect  as  diminution  or  incroaf 
of  external  pressure — so  that  the  quantity  of  any  given  gas  absorbed  by 
water  is  greater  at  low  than  at  higher  temperatures. 

When  a  mixture  of  two  gases  is  exposed  to  the  absorbing  action  of 
water,  both  are  absorbed  ;  but  the  quantity  of  each  gas  taken  up  is  less 
than  it  would  be  if  that  gas  alone  were  placed  in  contact  with  the  water. 

According  to  Dalton,  the  quantities  of  the  individual  gases  absorbed 
are  proportional  to  the  lolabibty  of  each  of  them  in  th«  separate  statey 


WATER.  67 

and  to  the  relative  quantities  of  them  present  in  tlie  unabeorbed  gaseous 
mixture.  For  example^  air  contains.  -^  of  its  Tolume  of  oxygen^  and  -^J^ 
of  nitrogen ;  and  since,  according  to  SanssurOj  1  yolume  of  water  absom 
iV  <>f  A  volume  of  oxygen,  and  -^  of  a  volume  of  nitrogen  gas, — it  follows 
that  1  volume  of  water  will  take  from  the  air  -nsViV  ^  0*0131  of  a  volume 
of  oxygen,  and  ^^.  -^  «■  0*0329  of  a  volume  of  nitrogen,  making  together 
0*040  of  a  volame.  Hence,  of  1 00  volumes  of  air  absorbed  by  water, 
28*5  are  oxygen,  and  71*5  nitrogen.  This  calculation  is  only  approxi- 
mately confirmed  by  experiment.  According  to  Von  Humboldt  «  Gay- 
Lussac,  distilled  water  saturated  with  air  yields,  when  boiled,  a  gaseous 
mixture  containing  32*8  per  cent,  of  oxygen  :  rain  water  yields  31*0, 
snow  water  28*7,  and  the  water  of  the  Seme,  from  29*1  to  31 '9  per  cent. 
Ddbereiner  found  by  repeated  experiments  (J.  pr.  Chem.  15,  286),  that 
the  air  expelled  by  boiling  from  aerated  water  contained  33*3  per  cent., 
or  exactly  \  of  oxygen  gas.  The  difference  between  the  results  of  calcu- 
lation and  experiment  seems  to  imply  that  the  solubility  of  oxygen  gas  in 
water  is  rather  greater,  and  that  of  nitrogen  rather  less,  than  Saussure's 
experiments  show.  {Compare  Configliachi,  Schw.  1,  151.  Thomson,  J. 
Chim.  Med.  13,  57.) 

When  a  mixture  of  two  or  more  of  the  less  solnble  gases  is  placed  in 
contact  with  water  in  a  confined  space,  the  relative  quantities  of  the 
several  ingredients  undergo  an  alteration,  unless  the  water  absorbs  all  the 
gases  in  the  proportions  in  which  thej'  are  mixed.  According  to  Dalton, 
the  following  law  always  holds  good :  Let  A,  B,  C,  .  .  .  denote  the 
volumes  of  the  several  gases  in  the  original  mixture ;  a,  6,  c,  .  .  .  the  quan- 
tities remaining  in  the  unabsorbed  residue ;  w  the  volume  of  the  water, 
Uf  iff  w 

*^^  ;:r>7r>  TT  •  • .  •  the  relative  volumes  of  the  several  frases  which  would 
m  n  p  ® 

be  absorbed,  if  each  of  them  were  present  by  itself  *.  then 


A  ^  a  + 
B  =  h  -j- 
O  —  c  + 


to  a 

m  *  a-f64-c.... 

iff  h 

n  '    a+5-hc... 
iff  c 


•    a-f6-fc... 

f^dA+B+C =  a+ft+c.   +    —^ (j^^±+±...) 

a+&+<?....  \  m       n       p      / 

The  absorption  of  gas  takes  place  the  more  quickly,  the  greater  th« 
external  pressure,  the  lower  the  temperature,  and  the  greater  the  number 
of  points  of  contact :  it  is  therefore  accelerated  by  agitation.  Whenever 
a  gas  is  absorbed  by  water,  heat  appears  te  be  set  free :  in  the  case  of  the 
more  easily  soluble  gases,  hydrochloric  acid  for  instance,  the  temperature 
may  rise  above  100°;  with  carbonic  acid,  on  the  contrary,  it  never  exeeeds 
a  quarter  of  a  degree ;  and  with  the  still  lees  soluble  gases  it  is  wholly 
inappreciable. 

The  liquid  formed  by  the  absorption  of  a  gas  in  water  always  oecn- 
pies  a  greater  volume  than  the  water  alone :  its  spedfio  gravity  is  in 
most  cases  greater ;  more  rarely,  as  in  that  of  ammonia,  less  than  that  of 
pure  water.  The  greater  the  density  of  a  gas,  the  greater  also  is  that  of 
its  aqueous  solution.  In  this  combination,  the  gas  has  lost  its  gaseous 
form  and  assumed  that  of  a  liquid :  the  combination  may  be  regarded 
as  that  of  a  less  volatile  liquid  with  one  possessing  greater  volatility. 
(Graham.)  v  2 


88  HYDROGEN. 

The  combination  is  destroyed:  1.  By  diminntion  of  atmospheric  pressure. 
—2.  By  rise  of  temperature. — 3.  By  access  of  other  gases. — 4.  By  access  of 
non-gaseous  substances  miscible  with  water. — 5.  By  congelation  of  the 
water. — 6.  By  peculiar  mechanical  conditions. 

1'.  Since,  when  a  ma  is  rarefied  100  times,  water  takes  up  just  as 
much  of  it  by  volume,  but  ouly  ^hs  ^  much  by  weight,  as  it  would  if  the 
gas  were  under  the  ordinary  atmospheric  pressure, — ^it  follows  that,  when 
water  saturated  with  gas  is  placed  under  the  receiver  of  the  air-pump,  the 
gas  will  escape  as  the  air  is  rarefied.  But  the  evolution  of  the  gas  is  never 
complete;  partly  because  it  is  impossible  to  produce  an  absolute  vacuum, 
— ^partly  because  the  afiinity  of  the  gas  for  the  water  ultimately  gains  the 
preponderance  over  its  elasticity.  In  the  case  of  the  less  soluble  gases, 
this  point  is  not  attained  for  a  considerable  time ;  but  with  those  which 
are  easily  soluble  it  is  very  soon  reached, — so  that,  from  aqueous  solution 
of  hydrochloric  acid,  for  example,  only  a  small  portion  of  the  hydrochloric 
acid  can  be  removed  by  the  air-pump,  and  then  the  remaining  compound 
of  the  water  with  the  acid  evaporates  unchanged. 

2!.  By  elevation  of  temperature,  the  elasticity  of  the  gas  is  increased 
and  its  absorbability  diminislied.  In  this  manner,  however,  only  a  portion 
of  the  gas  can  be  removed.  But  when  the  water  ultimately  boils,  the 
attraction  of  the  watery  vapour  for  tlie  gas  (compare  pp.  20  and  265, 
Vol.  I.)  seems  to  induce  the  latter  almost  entirely  to  abandon  its  state  of 
combination  with  the  liquid  water,  and  escape  in  company  with  the 
aqueous  vapour.  Hence,  by  several  hours'  boiling,  the  less  soluble  ^ases 
and  ammonia  may  be  expelled  from  water,  but  not  the  other  easily  soluble 
gases,  such  as  hydrochloric  acid.  Of  this  gas,  a  portion  may  be  evolved 
at  the  commencement ;  but  afterwards,  the  whole  of  the  water  and  acid 
evaporate  together  as  a  chemically  combined  whole ;  and  the  remaining 
portion  not  yet  evaporated  is  as  rich  in  hydrochloric  acid  as  that  which 
has  passed  over.  It  is  remarkable  that  nitrogen  gas  is  much  more  easily 
separated  from  water  by  boiling  than  oxygen  gas, — so  that  when  water 
containing  air  is  boiled  and  the  air  evolved  is  collected  in  separate  por- 
tions, the  first  portions  contain  proportionally  much  less  oxygen  and  more 
nitrogen  than  those  which  follow. 

3\  When  water  saturated  with  a  gas  A  comes  in  contact  with  another 
gas  B,  then,  according  to  Dal  ton's  law  above  given,  the  quantity  of  the 
first  gas  expelled  and  of  the  second  absorbed  will  be  such,  that  the  volume 

of  the  gas  A  remaining  in  solution  will  be  —  •  -qjr  ,  and  that  of  the  gas 

w  h 
B  absorbed,  ~  •  r*  If  both  gases  possess  the  same  degree  of  solu- 
bility, so  that  m=n,  the  gas  B,  which  is  brought  in  contact  with  the  water, 
will  suflfer  no  change  of  volume  by  being  converted  into  a  mixture  of  A 
and  B :  if,  on  the  contrary,  B  is  either  more  or  less  soluble  than  A,  the 
fi;aseous  mixture  formed  will  be  less  or  greater  in  volume  than  the  gas  B 
before  mixture.  When  water  saturated  with  any  gas  A  is  placed  in  con- 
tact with  the  open  air,  the  whole  of  A  is  set  free,  while  the  water  absorbs 
the  constituents  of  the  air.  For  if,  as  in  the  preceding  formula,  we  express 
by  a  the  quantity  of  the  gas  A  which  does  not  remain  dissolved  bat 
escapes,  and  by  b,  e,  d,  the  almost  infinite  quantity  of  the  non-absorbed 
oxygen,  nitrogen^  and  carbonic  acid  gases  which  constitute  the  common 

air,  the  fraction  ^  ■  ^  .  ^  .  ^  will  be  so  extremely  small,  that  when  mul- 


WATER.  69 

tiplied  by-^  ^  it  will  give  an  almost  evanescent  value  to  the  quantity  of 

the  gas  A  which  remains  absorbed  by  the  water,  when  the  liquid  is  exposed 
to  the  open  air.  On  the  contrary,  when  any  gas  confined  within  a  limited 
space — under  a  bell-jar,  for  instance — ^is  placed  in  contact  with  water  con- 
taining air,  it  is  in  part  absorbed  by  the  water,  while  the  oxygen  and 
nitrogen  gases  contained  in  the  water  pass  up  into  the  bell-jar,  and  mix 
with  the  unabsorbed  portion  of  the  other  gas.  But  inasmuch  as  motion 
is  continually  communicated  to  the  water  by  agitation  and  change  of 
temperature,  by  which  &esh  portions  of  aerated  water  are  continually 
brought  in  contoct  with  the  confined  gas,  the  water  ultimately  absorbs 
the  whole  of  that  gas,  and  discharges  it  into  the  air  at  another  place, 
while  the  bell-jar  becomes  filled  with  the  oxygen  and  nitrogen  of  the 
common  air. 

4'.  On  dissolving  various  salts  in  water  containing  any  gas  in  solution, 
or  adding  oil  of  vitriol  to  it,  &c.,  the  absorbing  power  of  the  water  is 
diminished,  in  consequence  of  the  new  combination  into  which  it  enters, 
and  a  portion  of  the  dissolved  gas  is  suffered  to  escape.  One  volume  of 
Seine  water,  from  which  0*018  of  a  volume  of  air  and  0'003  of  carbonic 
acid  may  be  expelled  by  boiling,  evolves,  when  mixed  with  1  volume  of 
strong  solution  of  potassa,  0*017  of  a  volume  of  air.  (Payen,  Ann,  Chim. 
Fhys,  50,  303.)  Water  saturated  with  sulphate  of  magnesia  absorbs  only 
\  as  much  carbonic  acid  and  \  as  much  hydrosulphuric  acid  as  pure  water; 
but  on  the  other  hand,  water  saturated  with  nitre  or  Glauber's  salt  absorbs 
as  much  of  these  two  gases  as  pure  water  does. 

5'.  When  water  combined  with  a  gas  of  which  it  can  onljr  take  up  its 
own  volume  at  the  utmost,  is  exposed  to  a  degree  of  cold  at  which  it  freezes, 
the  gas  which  it  has  absorbed  is  set  free  at  the  moment  of  solidification. 
On  the  contrary,  the  compounds  of  water  with  the  more  readily  soluble 
gases  freeze  altogether,  without  allowing  the  absorbed  gases  to  escape. 

6'.  When  water  containing  any  gas  is  subjected  to  a  lower  pressure  or 
a  higher  temperature  than  that  at  which  it  was  saturated,  the  portion  of 
the  gas  which — according  to  what  has  just  been  explained — ou^ht  to  be 
set  free,  does  not  always  escape  immediately.  Its  evolution  is,  however, 
accelerated  either  by  agitation  or  by  throwing  in  sand,  silver-leaf,  and 
other  angular  bodies,  or  by  the  immersion  of  glass  rods,  wires,  &c.  :  the 
immersed  bodies  immediately  become  covered  with  gas  bubbles,  (pp.  270, 
271,  Vol.  I.) 

All  compounds  of  water  with  gaseous  bodies  are  to  be  regarded  as 
chemicaL  DaJton  supposes  that  gases  of  which  water  does  not  absorb  at 
most  more  than  its  own  volume,  are  only  mechanically  absorbed  by  it,  so 
that  the  gaseous  particles  are  distributed  about  in  the  pores  of  the  water. 
(The  various  arguments  which  militate  against  this  assumption  I  have  put 
together  in  GthUr's  phyrUc.  Worterbuch.  Ausg.  2.  B.  1,  S.  73.) 

b.  The  8oltUi<m  of  liquid  and  solid  bodies  in  water  is  accompanied 
sometimes  by  development,  sometimes  by  absorption  of  heat.  According 
to  Gay-Lussac  (Ann,  Chim.  Phys,  70,  426),  all  salts,  such  as  nitre,  which 
are  incapable  of  combining  with  water  of  crystallization,  produce  a  fi^l  of 
temperature  when  they  dissolve;  the  others,  on  the  contrary,  such  as 
anhydrous  sulphate  of  soda,  produce  a  rise  of  temperature ;  consequently, 
the  latter  must  be  supposed  to  dissolve  in  combination  with  their  water  of 
crystallization.  Bo<ues  which  attract  vapour  of  water  from  the  air  and 
dissolve  in  it  are  said  to  be  Deliquescent.  This  deliquescing  tendency 
varies  with  the  temperature  and  hygrometrio  stat^  of  the  air.    (Gay- 


70  HTOBOOEN. 

LussaCy  GMb.  42,  246.)  Many  salts  effloresco  in  diy  and  deliquesce  in 
moist  air* 

The  density  of  a  solution  is  generally  abore  the  calculated  mean. 
The  water  in  solutions  is  generally  held  by  a  much  weaker  affinity  than 
that  which  exists  in  the  combinations  enumerated  under  the  head  A. 
Hence  when  the  temperature  is. reduced  below  0°,  a  part  of  the  water  or 
even  the  whole  of  it  separates  in  the  form  of  ice  (I.,  113).  Most  solutions 
have  boiling  points  above  that  of  pure  water  (I.,  269).  All  salts  may  be 
completely  dried  at  the  temperatures  at  which  their  saturated  solutions 
boil, — €,  g,  carbonate  of  potassa  at  135°,  chloride  of  calcium  at  180°. 
(Leffrand,  Ann,  Chim.  Phys,  59,  429  ;  also  J.  pr,  Chem,  6,  59.) 

It  is  remarkable  that  water  dissolves  but  few  simple  substances,  and 
these  in  small  quantity  only ;  that,  on  the  other  hand,  it  is  most  inclined 
to  dissolve  those  compounds  which  contain  one  or  both  of  its  constituents 
(as  is  more  particularly  seen  if  we  admit  the  conversion  of  haloid  salts  by 
water  into  hydrogen  salts  of  metallic  oxides)  ;  that  it  is  chiefly  through 
the  medium  of  water  that  the  acid  reaction  of  oxygen- acids,  and  the  alka- 
line reaction  of  the  fixed  alkalis  is  developed ;  that  many  bases  which  are 
insoluble  in  water  have  their  alkaline  reaction  brought  out  by  entering 
into  some  combination  by  which  they  are  rendered  soluble  in  water,  e.g. 
protoxide  of  lead  by  combination  with  a  small  quantity  of  acetic  acid, 
red  oxide  of  mercury  by  combination  with  hydrocyanic  acid.  (Oomp. 
Dobereiner,  G^ilb,  58,  213.) 

With  recpard  to  the  different  quantities  of  a  substance  which  water  can 
dissolve  at  different  temperatures,  the  following  cases  may  be  noticed  : — 

1.  The  same  quantity  is  dissolved  at  all  temperatures.  Such,  accord- 
ing to  Fuchs,  is  the  case  with  common  salt. 

2.  The  quantity  dissolved  continually  increases  with  the  temperature. 
In  this  case,  which  is  by  far  the  most  common,  the  quantity  taken  up  by 
the  water  is,  according  to  Gay-Lussac,  the  same  whether  the  water  is  agi- 
tated in  contact  with  the  suostance  till  the  point  of  saturation  at  the 
given  temperature  is  attained,  or  the  salt  is  dissolved  in  hot  water  and 
the  solution  left  to  stand  till  all  the  excess  of  salt  is  crystallized  out. 
When  water  is  saturated  with  a  salt,  especially  carbonate  of  potassa,  at  the 
particular  temperature  at  which  the  saturated  solution  boils,  the  liquid 
often  remains  at  that  heat  for  some  time  after  removal  from  the  fire  ;  but 
as  soon  as  the  salt  begins  to  separate,  a  constant  and  somewhat  lower 
temperature  is  established.  The  most  highly  saturated  solution  of  car- 
bonate of  potassa  exhibits  a  temperature  of  140°  ;  on  a  sudden  it  froths 
violently  up,  deposits  salt,  and  remains  for  some  time  at  135^.  (Legrand.) 

a.  The  solubility  of  the  substance  increases  in  direct  proportion  to  the 
temperatare.  If  we  know  the  solubility  of  such  a  substance  at  0^,  and 
likewise  the  additional  quantity  which  will  be  dissolved  at  a  temperature 
of  1°  higher,  we  have  sufficient  data  for  calculating  the  solubility  at  any 
other  temperature.  Thus,  100  parts  of  water  at  0°  dissolve  29*23  of 
chloride  of  potassium,  and  an  additional  0  2738  for  each  additional  de- 
gree of  temperature.  Hence,  the  solubility  at  40°  is  equal  to  29*28 
+  40  .  0*2738 =40' 18.  Similarly,  with  regard  to  sulphate  of  potassa, 
chloride  of  barium,  and  anhydrous  sulphate  of  magnesia.     (Gay-Lussao.) 

*  To  fret  a  gas  oompletdy  from  yapomr  of  water  it  is  usual  to  place  within  it  some 
labstanoe  baYing  a  very  strong  attraction  for  water,  t.f.  hydrate  of  potassa,  hydrate  of 
fodSf  baryta,  ttrontia,  ]ime,  mi  of  ntriol,  phosphoric  add,  nitrate  of  lime,  acetate  of 
potassaj  diloride  of  calcium,  nitrate  or  hydrochlorate  of  magnesia,  burnt  gypsum,  &c. ; 
to  else  a  body  which  forcibly  takes  hold  of  the  individual  constituents  of  the  water :  e.y. 
I  fluoride  of  boron. 


WATBIU  71 

b.  The  solubility  increases  much  more  rapidlj  than  the  tetnperatare, 
its  increase  being  represented  by  a  curve  with  its  conyezity  downwards. 
This  is  the  case  with  nitrate  and  chlorate  of  potaasa  and  nitrate  of 
baryta. 

8.  The  solnbility  of  the  substance  decreases  as  the  temperature  rises. 
This  rare  peculiarity  is  exhibited  by  lime,  citrate  of  lime,  butyrate  of  lime, 
and  sulphate  of  cerium, — solutions  of  which  substances  saturated  in  the 
cold  deposit  part  of  the  dissolved  matter  when  the  temperature  is  raised. 

4.  The  solubility  of  the  substance  increases  at  first  at  a  rapid  rate  as 
the  temperature  rises,  as  in  2,  6 ;  but  reaches  a  maximum  at  a  certain 
point,  and  diminishes  from  this  point  slowly  and  continuously,  as  the 
temperature  is  still  further  raised.  100  parts  of  water  at  0^  dissolve 
12*17  parts  of  crystalized  sulphate  of  soda;  at  18^  48  parts;  at  25**, 
100  parts  ;  at  32"^,  270  parts  ;  at  33°,  the  maximum  quantity,  viz.,  322 
parts ;  and  at  60*4°,  262*55  parts.  (Qay-Lussac.^  From  the  saturated 
solution  at  33®  ^91*4°  F.)  hydrated  salt  crystallizes  out  on  cooling, --<i- 
anhydrous  salt  when  the  temperature  is  further  raised. 

VVhen  two  salts,  A,  B,  which  neither  decompose  each  other  nor  com* 
bine  to  form  a  double  salt,  are  brought  in  contact  with  water  at  the  same 
time,  and  in  such  Quantities  that  a  portion  of  each  of  them  remains  undis- 
solved, the  water  dissolves  a  larger  quantity  of  the  whole  than  it  would 
of  either  salt  alone  ;  and,  according  to  Karsten,  there  are  the  three  fol- 
lowing cases  to  be  considered  : — 

1.  In  the  saturated  solution  of  A,  B,  the  water  holds  in  solution  a 
smaller  quantity  of  A  than  it  would  if  saturated  with  A  alone  ;  and  less 
of  B  than  if  saturated  with  B  alone.  In  this  case  there  is  a  reciprocal 
partial  separation  :  A  added  to  the  saturated  solution  of  B  separates  a 
portion  of  B,  and  B  added  to  the  saturated  solution  of  A  separates  a  por- 
tion of  A.  But  whether  we  proceed  in  the  first  way,  or  in  the  second,  or 
add  both  salts  in  excess  to  the  water  at  once,  the  quantity  of  each  salt 
taken  up  by  the  water  is  invariably  the  same.  Thus,  sal-ammoniac  added 
to  a  saturated  solution  of  common  salt  separates  a  portion  of  that  salt  in 
cubes,  and  common  salt  added  to  a  saturated  solution  of  sal-ammoniac 
separates  a  portion  of  the  sal-ammoniac  in  dendrites.  At  18  75°,  100 
parts  of  water  dissolve  29*83  sal-ammoniac  and  16*27  chloride  of  po- 
tassium, making  together  46*1 ;  the  same  quantity  o^  water  dissolves 
22*05  sal  ammoniac  and  32*64  common  salt,  making  together  48*44 ; 
also  24*98  common  salt  and  52*82  nitrate  of  soda,  making  together 
77*8.  Similar  relations  are  exhibited  by  sal-ammoniac  with  nitrate 
of  ammonia  or  chloride  of  barium ; — chloride  of  potassium  with  com- 
mon salt  or  chloride  of  barium ;-— common  salt  with  chloride  of  ba- 
rium;— ^nitrate  of  ammonia  and  nitrate  of  soda  appear  likewise  to 
act  upon  each  other  in  a  similar  manner,  excepting  that  the  partial 
separation  of  the  former  by  the  latter  does  not  tiu^e  place  till  after 
several  hours.  When  eoual  parts  of  the  saturated  solutions  of  sal- 
ammoniac  and  common  salt  are  mixed  together,  no  change  of  temperature 
takes  place,  but  a  mixture  is  formed  capable  of  still  dissolving  both  com- 
mon salt  and  sal-ammoniac.  When  this  mixture  of  two  saturated  solutions 
is  heated  in  contact  with  common  salt,  it  dissolves  but  a  very  small  addi- 
tional quantity  of  that  substance ;  but  when  heated  with  sal-ammoniac,  it 
dissolves  the  first  portions  clearly,  without  depositing  anything ;  the  solu- 
tion of  the  following  portions  is  accompanied  by  separation  of  common 
salt,  the  quantity  thus  separated  increasing  with  tne  temperature :  on 
cooling,  the  sal-ammoniftc  crystallizes  out  and  the  precipitated  chloride  of 
sodium  redissolves. 


72  HYDROGEN. 

2.  The  water  dissolres  the  same  qnantit;^  of  the  salt  A,  whether 
that  salt  is  presented  to  it  alone^  or  in  conjunction  with  the  salt  B  : 
on  the  contrary,  it  dissolres  less  of  B  when  B  is  in  conjunction  with 
A,  than  when  it  is  brought  in  contact  with  the  water  by  itself.  In  this 
case,  a  one-sided  partial  separation  takes  place  :  A  dissolves  in  the  satu- 
rated solution  of  B  in  the  same  proportion  as  in  pure  water,  causing  a 
portion  of  B  to  crystallize  out ;  but  B  dissolves  in  the  saturated  solution  of 
A  in  smaller  quantity  than  in  pure  water,  without  giving  rise  to  the 
separation  of  any  portion  of  A.  In  whichever  order  the  process  may  be 
conducted,  the  same  solution  is  obtained  as  when  an  excess  of  both  A  and 
B  is  placed  in  contact  with  water. 

100  parts  of  water  at  18*75''  dissolve  33  07  chloride  of  potassium 
toother  with  1*79  sulphate  of  potassa,  together  =  34*86  ; — 29*42  nitre 
with  4*00  sulphate  of  potassa,  together  =  33*42  ; — 88*14  nitrate  of  soda 
with  3*77  nitrate  of  baryta,  together  =  91*91  ; — 87'75  nitrate  of  soda 
with  34*26  nitrate  of  lead,  together  =  12201.  The  following  behave  in 
a  similar  manner:  chloride  of  potassium  with  sulphate  or  nitrate  of 
potassa, — nitrate  of  potassa  with  nitrate  of  ammonia  or  sulphate  of 
potassa, — common  salt  with  cnrstallized  suljphate  of  soda  or  sulphate  of 
magnesia, — nitrate  of  soda  with  sulphate  of  soda,  sulphate  of  magnesia, 
nitrate  of  baryta,  nitrate  of  lead,  or  sulphate  of  zinc  (excepting  that  in  the 
last  case,  crystals  double  of  sulphate  of  zinc  and  potassa  are  produced  after  a 
time), — nitrate  of  lead  with  nitrate  of  baryta.  The  first-named  salt  is  in 
all  cases  the  salt  A,  which  dissolves  in  equal  quantity  whether  the  water 
is  pure  or  already  contains  the  salt  B. 

3.  A  given  quantity  of  water  dissolves  more  of  the  salt  A  when  that 
salt  is  presented  to  it  in  conjunction  with  B  than  when  it  is  alone,  and  at 
the  same  time  also  a  larger  quantity  of  the  salt  B.  In  this  case,  no  pre- 
cipitation takes  place  on  addinff  B  to  the  saturated  solution  of  A;  on  the 
contrary,  this  solution,  after  B  has  been  added  to  it,  takes  up  a  fresh  por- 
tion of  A;  similarly  when  A  is  added  to  the  saturated  solution  of  B.  In 
order,  therefore,  to  obtain  a  constant  proportion,  both  salts  must  be  added 
to  the  water  in  excess. 

It  appears  then  that  there  are  three  kinds  of  saturaticm  to  be  dis* 
tinguished:  (a.)  The  saturation  by  B  of  100  parts  of  water  already 
saturated  with  A. — (b^  The  saturation  by  A  of  100  parts  of  water 
already  saturated  with  B. — (c.)  The  saturation  of  100  parts  of  water  by 
an  excess  of  the  two  salts  at  once ;  in  all  cases  at  1 8*75    (65*75  F.) 

a  b  e 

A  Sal-ammoniAC  37*98    44*33    39*84 
B  Nitre 37*68    30*56    38*62 

75-66     74-89     79.46 

a  b       e  a  b  e 

A  Sal-ammonuc  ••  38*04      38-6    39*18       Nitrate  of  potassa  29*45    33*12    38-53 
B  Nitrate  of  baryta  16*73        8-6     17*02        Common  gait    ..   38*25    36-53    39-19 

54-77    47*2    56-20  67*70    69*65    77*7^ 

A  Nitrate  of  potassa  29*45    35*79  Nitrate  of  potassa     29*9    53*04      59*2 

B  Nitrate  of  soda. .   89*53     88*00 Nitrate  of  lead   ..     84-1     51-56     109*8 

118*98  123-79  111-4  107*60     169*2 

Similar  relations  are  exhibited  by  sal-ammoniac  with  common  salt  or 
sulphate  of  potassa ;  nitrate  of  ammonia  with  nitrate  of  lead;  sulphate  of 


PEROXIDE  OF  HYDROGEN.  73 

potaesa  with  snlphate  of  soda,  common  salt,  or  sulphate  of  magnesia  (in 
the  last  case  a  donble  salt  is  fonned);  chloride  of  potassium  with  nitrate 
of  baryta;  nitrate  of  potassa  with  sulphate  of  soda;  sulphate  of  soda  with 
sulphate  of  nuignesia  or  snlphate  of  copper  (in  which  case  a  double  salt 
is  termed) ;  nitrate  of  baryta  with  common  salt  or  chloride  of  barium. 

Solution  of  three  Salts,  From  a  saturated  solution  of  sal-ammoniac 
and  chloride  of  potassium  together,  the  addition  of  common  salt  precipi- 
tates both  sal-ammoniac  and  chloride  of  potassium  :  similarly,  chloride  of 
potassium  added  to  a  saturated  solution  of  sal-ammoniac  and  common  salt 
throws  down  a  portion  of  both  those  salts.  On  adding  nitrate  of  lead  to 
a  saturated  solution  of  nitrate  of  potassa  and  nitrate  of  soda,  the  solution 
remains  clear,  and  is  no  longer  in  a  state  of  saturation  :  it  contains  in  100 
parts  of  water,  134'38  nitrate  of  potassa  and  nitrate  of  soda,  and  43*75 
nitrate  of  lead,  together  amounting  to  178*13.  When  fully  saturated 
with  all  three  salts,  it  contains  139*23  nitrate  of  potassa  and  nitrate  of 
soda,  and  53*24  nitrate  of  lead,  making  together  192*47.  Similarly,  a 
solution  saturated  with  nitrate  of  potassa  and  nitrate  of  lead  is  not  pre- 
cipitated by  nitrate  of  soda;  and  a  solution  saturated  with  nitrate  of  lead 
and  nitrate  of  soda  is  not  nrecipitated  by  nitrate  of  potassa.  In  both 
cases  the  solution  is  found  to  be  unsaturated.  Thus  far,  Karsten 
{Sckrifi  d.  Berl.  Ahad.  1841). 

100  parts  of  water  dissolve  : 

at  16-1® :  27*1  chloride  of  potasdom  and  3*3  sulphate  of  potassa,  together  30*4 
at  15-3  :  28*8  chloride  of  potasshim  and  18*9  nitrate  of  potassa,  together  47*4 
at  20*0** :  6*9  snlphate  of  potassa. .  and  26*7  nitrate  of  potassa,  .  together  33*6 
at  16*8^ :  27*7  chloride  of  potaasinm  and  18*2  chloride  of  harinm,  together  45*9 
at  21*5**:  33*1  nitrate  of  potassa  ..  and  5*7  nitrate  of  haryta,..  together  38*8 
at  20"*  :  59*5  nitrate  of  potassa  . .  and  94*3  nitrate  of  lead,. . . .  together  153*8 
at  18*3^ :  35*0  chloride  of  sodinm  . .  and  4*2  chloride  of  harinm,  together  39*2 
at  20^  :  88*3  nitrate  of  soda  ....  and  3*7  nitrate  of  haryta,..  together  92*0 
at  20''     :  84*6  nitrate  of  soda     ....   and  38*4  nitrate  of  lead,    ..   together  123*0 

(Kopp.  Ann,  Pharm.  34,  260). 

Nitrate  of  potassa  dissolves  more  abundantly  in  water  containing  com- 
mon salt  or  nitrate  of  lime  than  in  pure  water.  {Comp,  Longchamp, 
Ann,  Ghim.  Phys,  9*5,  also  N.  Tr,  3,  1,  209.)  Gjpsum  dissolves  more 
abundantly  in  wat^r  containing  common  salt  than  m  pure  water. 

On  the  other  hand,  when  a  solution  of  nitrate  of  lime  is  mixed  with  a 
solution  of  nitrate  of  magnesia^  a  portion  of  the  latter  is  precipitated 
(Dijonval)  ;  and  according  to  Hermann  {Schw,  47,  201),  when  a  concen- 
trated solution  of  chloride  of  calcium  is  mixed  with  solution  of  common 
salt,  a  portion  of  the  common  salt  is  separated. 


B.    PfiBoxiDB  OF  Htdrooen.    HO'. 

Oxygenated  Water,  Eau  oxygenie,  Deutoxyde  d^hydrog^ne,  WoBeerstoff- 
hyperoxyd,  Satterstof-wasser. 

Pormation.^^When  peroxide  of  potassium,  sodium,  barium,  stron- 
tium, or  calcium,  is  disested  in  any  hydrated  acid  which  forms  a  soluble 
salt  with  the  salifiable  base  resulting  from  the  decomposition  of  the 
peroxide,  the  excess  of  oxygen  from  the  peroxide  does  not  escape  as  gas, 
out  passes  over  to  a  portion  of  the  water,  and  converts  it  into  peroxide  of 
hydrogen.    (Scheme,  105.)    Th^nard. 

When  black  oxide  of  manganese  purified  by  boiling  w^ter  from 


74  HTDROGSN. 

metallio  chlorides,  is  mixed  in  a  corked  flask  with  f  of  iU  weight  of 
faming  sulphuric  acid  and  6  times  its  weight  of  water,  and  the  mixture 
left  to  stand,  the  waterj  liquid  acquires  an  odour  resembling  that  of 
chlorine,  and  the  property  of  bleaching  litmus.  Peroxide  of  lead  yields 
a  liquid  haring  still  more  powerful  bleaching  properties.  (A.  Voee), 
J,  pr.  Chem.  \,  448.)  Lampadius  (J.  pr.  Cktm.  17,  36)  obtained  a 
bleaching  liquid  with  1  part  of  peroxide  of  lead,  ^  oil  of  yitriol,  and  21 
water,  the  mixture  being  put  into  a  bottle,  kept  at  0%  and  freauentlj 
shaken.  (Oil  of  yitriol,  even  the  fuming  varietj,  may  contain  chlorine  : 
vid.  sulphuric  acid.)  According  to  De  Marty,  water  saturated  with  oxy- 
gen gas  still  continues  to  absorb  that  gas  when  left  in  contact  with  it  for 
a  considerable  time,  so  that  in  the  course  of  a  year  and  a  half,  it  takes  up 
half  its  volume  of  the  gas  :  this  effect  may  perhaps  be  attributed  to  the 
formation  of  a  small  quantity  of  peroxide  of  hydrogen.  Paul  succeeded 
by  forcible  compression  in  causing  2  volumes  of  water  to  take  up  one 
volume  of  oxygen  gas. 

Proration.— Pure  baryta  is  prepared  by  igniting  in  a  porcelain 
retort  nitrate  of  baryta  free  from  iron  and  manganese.  The  baryta,  broken 
into  pieces  about  the  size  of  a  nut,  is  then  put  into  a  coated  fflass  tube  and 
heated  to  low  redness,  while  a  current  of  oxygen  gas  free  from  carbonic 
acid  and  dried  by  means  of  quicklime,  is  passed  over  it.  For  the  first 
eight  minutes  the  gas  is  eagerly  absorbed  by  the  baryta.  After  it  has 
begun  to  escape  from  the  farther  end  of  the  tube  ^to  which  a  gas  delivery- 
tube  passing  under  water  is  fitted),  the  stream  is  still  kept  up  for  the 
space  of  ten  or  fifteen  minutes.  The  peroxide  of  barium  obtained  by  this 
process  is,  after  cooling,  preserved  in  a  bottle.  In  the  next  place,  200 
grammes  of  water  are  mixed  with  as  much  hydrochloric  acid  as  will  neu- 
tralize about  15  grammes  of  baryta.  Into  this  liquid,  contained  in  a 
cylinder,  or  better,  in  a  dish  of  silver  or  platinum  kept  cool  by  sur- 
rounding it  with  ice,  12  grammes  of  peroxide  of  barium,  slightly  moistened 
and  rubbed  up  in  an  agate  mortar,  are  introduced  by  means  of  a  wooden 
spatula  :  on  agitating  or  stirring  the  liquid  with  the  pestle,  the  whole 
dissolves  completely  and  without  effervescence.  The  baryta  is  next  pre- 
cipitated by  oil  of  vitriol  added  drop  by  drop  till  slightly  in  excess  :  the 
presence  of  an  excess  of  the  acid  may  be  known  by  the  sulphate  of  baryta 
falling  down  more  quickly  than  before.  12  grammes  more  of  the  peroxide 
are  then  dissolved  in  the  same  liquid,  and  likewise  precipitated  by  sul- 
phuric acid.  The  liquid,  which  now  contains  hydrochloric  acid,  sulphuric 
acid,  a  large  quantity  of  water,  and  a  small  quantity  of  peroxide  of  hydro- 
gen, is  next  separated  by  filtration  from  the  sulphate  of  baryta,  the  pre- 
cipitate washed  with  a  little  water,  and  the  last  wash-water  retained  for 
future  washings.  The  filtrate  is  again  mixed,  as  above,  twice  with 
peroxide  of  barium,  and  twice  with  sulphnric  acid.  The  filtration  is  then 
repeated,  and  the  process  continued  in  the  same  way,  till  90  or  1 00  gram- 
mes of  the  peroxide  are  consumed.  The  liquid  thus  obtained  would,  on 
decomposition,  yield  from  25  to  30  measures  of  oxygen  gas.  To  separate 
silica,  alumina,  sesqui-oxide  of  iron,  sesqui-oxide  of  manganese,  dec,  which 
proceed  from  the  porcelain  retort  in  which  the  nitrate  of  baryta  was  ignited, 
the  liquid  is  mixed  with  concentrated  solution  of  phosphoric  acid  (2  or  8 
parts  of  phosphoric  acid  to  100  parts  of  peroxide  of  barium), — ^ihen  sur- 
rounded with  ice,  and  supersaturated  with  pounded  peroxide  of  barium  : 
silica  and  the  phosphates  of  iron,  manganese,  and  alumina  then  separate 
rapidly  in  flakes^  and  most  b«  separated  from  the  liquid  by  filtration 


PEROXIDB  OF  HYDROGEN.  75 

through  lineD,  and  if  Deoesaary,  through  paper.     The  presence  of  a  large 
quantity  of  sulphate  of  baryta  renders  the  filtration  difficult.    (If  no  phos- 

S boric  aoid  were  present,  the  sesquioxides  of  iron  and  manganese  would  fall 
own  by  themselves,  and  give  rise  to  a  rapid  evolution  of  oxygen  gas ; 
but  when  they  are  mixed  with  phosphoric  acid,  they  do  not  produce  this 
effect)  Should  the  liquid  still  contain  portions  of  these  oxides,  they  must 
be  separated  by  the  addition  of  a  slight  excess  of  bary ta- water ;  where- 
upon, the  liquid  must  be  immediately  and  rapidly  filtered  through  several 
filters  at  once,  and  the  filters  saueesed  between  linen  to  get  all  out.  The 
whole  of  the  baryta  must  then  be  separated  by  carefully  adding  sulphuric 
acid  in  very  slight  excess,  and  filtering.  The  filtrate  now  contains  nothing 
but  water,  peroxide  of  hydrogen,  hydrochloric  acid,  and  a  very  little  sul- 
phuric acid.  To  separate  the  hydrochloric  acid,  the  liquid  is  surrounded 
with  ice,  and  mixed  with  sulphate  of  silver.  In  the  first  place,  sulphate 
of  silver,  obtained  by  heating  nitrate  of  silver  in  contact  with  oil  of  vitriol 
in  a  platinum  crucible,  is  introduced  in  the  form  of  powder  into  the  liquid, 
— the  whole  being  constantly  stirred — till  the  liquid  becomes  clear,  a 
sign  that  the  hydrochloric  aoid  is  wholly  or  nearly  precipitated.  Any 
hydrochloric  acid  which  may  still  remain  must  be  separated  by  cautiously 
adding  more  sulphate  of  silver.  If  the  latter  has  been  added  in  excess,  it 
must  be  precipitated  by  carefully  dropping  in  a  dilute  solution  of  chloride 
of  barium.  The  liquid  should  contain  neither  hydrochloric  acid  nor  silver, 
and  should  therefore  give  no  precipitate  either  with  solution  of  silver  or 
with  hydrochloric  acid.  The  chloride  of  silver  is  separated  by  filtration 
and  pressure,  any  portion  of  liquid  which  comes  through  turbid  being 
filtered  over  again.  To  remove  the  sulphuric  acid  also,  and  obtain  a  pure 
mixture  of  water  and  peroxide  of  hydrogen,  the  liquid  is  placed  in  a  glass 
mortar  surrounded  with  ice,  and  rubbed  up  with  slaked  baryta  previously 
pKOunded  and  diffused  through  water  :  the  baryta  is  added  till  the  sulphu- 
ric acid  is  very  nearly  saturated.  The  liquid  is  then  filtered,  the  filter 
pressed  between  linen,  and  baryta-water  added  in  slight  excess :  this 
often  occasions  the  precipitation  of  oxide  of  iron  and  oxide  of  manganese, 
as  well  as  sulphate  of  baryta ;  hence  the  filtration  must  be  rapidly  per- 
formed. The  excess  of  baryta  is  removed  by  cautiously  adding  dilute 
sulphuric  acid,  so  that  there  may  be  rather  a  very  slight  excess  of  the  acid 
than  of  the  baryta.  (The  whole  of  the  sulphuric  acid  may  likewise  be 
removed  by  means  of  carbonate  of  baryta  obtained  in  a  finely-divided 
state  by  precipitation,  instead  of  by  slaked  baryta  and  baryta -water.) 
Finally,  to  separate  the  whole  or  nearly  the  whole  of  the  water,  the  vessel 
containing  the  liquid  is  placed  in  a  dish  containing  oil  of  vitriol,  and  the 
whole  placed  under  the  receiver  of  the  air-pump :  the  water  then  evapo- 
rates before  the  peroxide  of  hydrogen.  The  tlnid  is  agitated  from  time 
to  time.  If  it  should  deposit  flakes  of  silica,  which  give  rise  to  the  escape 
of  oxygen  gas,  it  must  be  decanted  off  from  them  by  means  of  a  siphon  :  if 
it  should  evolve  oxygen, — which  it  will  do  as  soon  as  it  is  so  far  concen- 
trated as  to  contain  about  250  times  its  volume  of  oxygen— two  or  three 
drops  of  sulphuric  acid  must  be  added  to  it.  The  concentration  must  be 
stopped  after  a  few  days,  when  the  liquid  is  brought  to  such  a  state  that 
when  decomposed  it  would  evolve  475  volumes  of  oxygen  gas ;  for  this 
residue,  if  left  longer  in  vacuo,  would  evaporate  as  a  whole.  The  peroxide 
of  hydrogen  must  be  kept  in  long  glass  tubes  closed  with  stoppers  and 
surrounded  with  ice ;  but,  even  under  these  eircumstances,  it  decomposes 
slowly  and  evolves  oxygen  gas.     (Thenard.) 

2.  Peroxide  of  banum  is  decomposed  by  hydrated  hydrofluoric  aoid  or 


76  HTDKOGEN. 

solation  of  hydrofluosilicic  acid,  the  whole  being  kept  constantly  cool :  in 
this  case,  insoluble  fluoride  of  barium  or  double  fluoride  of  siliclum 
and  barium  separates  at  once.  As  soon  as  a  sufficient  quantity  of 
acid  and  peroxide  of  barium  have  been  mixed,  the  peroxide  of  hy- 
drogen, still  containing  a  large  quantity  of  water,  is  filtered  from  the 
precipitate  and  concentrated  in  vacuo  oyer  oil  of  vitriol.  (Pelouse,  Berz, 
Zehrb.  1,411.) 

Properties. — Colourless,  transparent  liquid,  of  specific  gravity  1'452  ; 
does  not  freeze  at— SO"*  (—22°  F.) ;  evaporates  in  vacuo  at  ordinary 
temperatures  without  decomposition,  though  much  less  readily  than 
water ;  does  not  redden  litmus,  but  gradually  bleaches  both  litmus  and 
turmeric  paper;  has  a  harsh,  bitter  taste,  similar  to  that  of  tartar-emetic ; 
whitens  the  tongue  and  thickens  the  saliva ;  when  placed  upon  the  hand, 
it  instantly  turns  the  cuticle  white,  and  after  a  time  produces  violent 
itching.     (Th^nard.) 

Calcolmtion.  Th^nard.  Vol. 

H  1  5-88  6-02        Hydiogen  gas        1 

20        16        9412        93-98        Oxygen  gas..         1 

HO«      17      10000      10000 
(H*  O*  s=  2   .  6-2398   +  2  .  100    =     212-48    .    BcneUos.) 

Deeompodtions. — The  second  atom  of  oxygen  is  retained  by  the  hy- 
drogen very  loosely.  Under  various,  and  often  enigmatical  circumstances, 
it  separates  from  the  water  in  the  form  of  gas,  the  volume  of  which  at 
14°  (57-2^  F.)  and  0-76-.  bar.  (29-8  inches)  amounts  to  475  times  that  of 
the  liquid.  The  gas  often  escapes  with  such  rapidity  as  to  produce 
violent  effervescence,  and  even  explosion.  Great  heat  is  also  developed, 
and  when  the  experiment  is  made  in  the  dark,  even  light  is  apparent 
(I.,  234).  The  effect  of  explosion  is  most  readily  produced  by  oxide  of 
silver,  red  or  brown  peroxide  of  lead,  peroxide  of  manganese,  osmium, 
platinum,  and  silver,  the  peroxide  of  hydrogen  being  suffered  to  fall  in 
drops  on  these  substances  reduced  to  the  state  of  extremely  fine  powder. 

The  several  modes  of  decomposition  are  as  follows  : — 

1.  In  the  circuit  of  the  voltaic  battery,  peroxide  of  hydrogen,  like 
water,  is  gradually  resolved  into  hydrogen  at  the  negative  and  oxygen  at 
the  positive  pole, — only  that  the  proportion  of  oxygen  is  greater  than 
in  the  decomposition  of  water.     (Th^nard.) 

2.  By  a  certain  elevation  of  temperature.  At  freezing  temperatures, 
peroxide  of  hydrogen  is  but  very  slowly  decomposed ;  at  ordinary  tem- 
peratures, it  merely  evolves  a  bubble  of  hydrogen  now  and  then,  the  de- 
composition not  being  complete  for  months  ;  at  20°  (68°  F.)  the  escape  of 
gas  becomes  more  perceptible.  By  suddenly  raising  the  temperature  to 
100%  this  gradual  escape  of  gas  may  be  converted  into  a  kind  of  explo- 
sion. Finally,  there  remains  behind  nothing  but  pure  water.  Sunshine 
does  not  appear  to  accelerate  the  decomposition  at  ordinary  temperatures. 
(Thenard.) 

3.  By  contact  with  certain  substances,  which  either  remain  unaltered, 
or  take  up  part  of  the  oxygen  of  the  peroxide,  or  on  the  contrary  them- 
selves evolve  oxygen. — The  rapidity  with  which  these  substances  induce 
the  separation  of  oxygen  from  the  peroxide  depends  partly  on  their  che- 
mical nature,  partly  on  the  minuteness  of  their  mechanical  division : 
the  further  this  is  carried,  the  more  rapid  is  the  action.  (Thenard.  See 
I.,  114,  115.) 


PEROXIDE  OF  HYDROGEN.  77 

cr.  Svhdances  which  induce  the  evoltUum  of  oxygen  without  thenuelvee 
undergoing  any  alteration.      The  following   act  violently: — Charcoal 
(without  formation  of  carbonic  acid),  silver,  gold,  platinam,  palladium, 
rhodium,  iridium,  osmium.     (Silver  precipitated  by  zinc,  and  gold  preci- 
pitated by  protosulphate  of  iron,  act  with  violence;  silver  in  filings, 
slowly — ^in  the  massive  state,  very  feebly;  spongy  platinum  acts  still  more 
violently  than  precipit-ated  silver  or  gold ;  a  still  more  energetic  action  is 
produced  by  osmium  ;— -on  the  other  hand,  spongy  palladium,  rhodium, 
and  iridium,  obtained  by  igniting  the  ammonio-chlorides,  act  somewhat 
less  strongly  than  precipitated  silver. )«- A  moderate  action  is  produced 
by  mercury,  lead  filings,  finely  pounded  bismuth,  powdered  manganese ; 
a  very  slight  action  by  copper,  nickel,  cobalt,  and  cadmium.     The  fol- 
lowing likewise  induce  violent  decomposition  :   Sesqui-oxide  and  per- 
oxide of  manganese,  sesqui-oxide  of   cobalt,   massicot ; — ^moderate  de- 
composition is  induced  by  hydrated  sesqui-oxide  of  iron,  the  hydrates  of 
potassa  and  soda  {evea  when  dissolved  in  water),  hydrate  of  magnesia,  and 
hydrated  oxide  ot  nickel ; — a  feeble  action  by  sesqui-oxide  of  iron,  oxide 
of  nickel,  protoxide  of  copper,  oxide  of  bismuth,  magnesia ; — ^very  feeble  by 
black  oxide  of  iron,  sesqui-oxide  of  uranium,  bi-oxide  of  titanium,  sesqui- 
oxide  of  cerium,  oxide  of  zinc,  the  hydrated  peroxides  of  barium,  stron- 
tinm  and  calcium  ; — still  more  feeble  by  carbonate  of  soda,  bicarbonate 
of  potassa,  protosulphate  of  manganese,  sulphate  of  zinc,  protosulphate  of 
iron,  and  sulphate  of  copper ;  sal-ammoniac,  the  chlorides  of  potassium, 
sodium,  banum,  calcium,   antimony,  and  manganese;    and  nitrate  of 
manganese,   nitrate  of  copper,  subnitrate  of  mercury,  and  nitrate  of 
silver.    Rapid  decomposition  is  likewise  produced  by  fibrine  of  blood 
(which  seems  to  undergo  no  change  by  the  action — for  it  may  be  re- 
peatedly used  for  the  same  purpose),  and  by  the  washed  parenchyma  of  the 
Jungs,  nerves,  and  spleen  (the  oxygen  set  free  by  these  animal  structures 
is  free  from  carbonic  acid  and  nitrogen);  whereas  white  of  egg  both  liquid 
and  coagulated,  glue,  and  urea  exert  no  decomposing  action.     (Thenard.) 
h,  Suhglaneee  which  not  only  separate  oxygen  from  the  peroxide,  but  at 
the  saiM  time  give  up  their  own  oxygen  and  are  reduced :  Hydrated  bi- 
oxide  of  platinum,  oxide  of  gold,  oxide  of  silver,  protoxide  of  mercury 
(which  are  reduced  to  the  metallic  stated  and  the  red  and  brown  peroxides 
of  lead  (which  are  reduced  to  the  state  ot  protoxide).  With  all  these  oxides, 
the  action  is  very  violent.     The  reduction  of  oxide  of  silver  takes  place 
even  with  peroxide  of  hydrogen  considerably  diluted  with  water.     (The- 
nard.)—For  the  cause  of  the  reduction,  see  Vol.  I.,  p.  115.  Thenard  and 
Mit6<uierlich  {Pogg.  55,  321)  regard  it  as  a  consequence  of  the  develop- 
ment of  heat. 

c.  The  following  substances,  while  they  allow  a  certain  portion  of 
oxygen  from  the  peroxide  of  hydro^n  to  escape  as  gas,  absorb  the  re- 
mainder, and  are  converted  into  the  mllowing  compounds: — Selenium  into 
selenic  acid  (with  great  development  of  heat,  but  without  light);  potas- 
sium or  sodium  into  potassa  or  soda  (with  combustion,  evolution  of  oxygen 
gas,  and  often  explosion) ;  arsenic  into  arsenic  acid ;  molybdenum  into 
molybdic  acid  (these  two  with  violent  action  and  combustion :  dilute 
peroxide  of  hydrogen  dissolves  arsenic,  and  converts  it  into  arsenic 
acid  without  effervescence);  tungsten  into  tungstic  acid  (moderate); 
chromium  into  chromic  acid ;  zinc  into  oxide  of  zinc  (very  feeble)  ;- 
hydrate  of  baryta  into  hydrated  peroxide  of  barium;  nydrated  pro- 
toxide of  copper  into  the  yellow  hydrate  of  a  higher  oxiae ;  hydrated 
protoxide  of  manganese  mto  the  hydrated  peroxide;  hydrated  pro- 


M*f«><«  "vf  sra»:^  zzA  m^r  ..'ie  c-^  v-^jMnsa  (vitk  ▼vlnit 
4^«n  t«*v:>r::j  .  ^*»  :^*^  •^.Tftinr  air:*i  ^A-i  simir  or  ■ol  i  fc<Ki  acid  ; 
wr,,y\  .'^  '/  «a*.-»-.cT.  jo^  ,Tr^,  r,r  ci&c  pvT.  wri^  i.nmt  rt5e  •£  te»peiat«ri^ 
».'.*^  '.v%  tn  ;.fiA£ifr ''.f  :£«^ vrr^^fntm iizg  oj.^  * «^i}p<i>ie  9/ iiwth  wad bissl- 
p:  ->  'vf  tt*  a^  ▼♦*▼  fc^.iT  ;  pro<*j«K.lpL:.i*  orf"  m^frvrj  and  nipkkle  of 
<t..T*y.  ft^.n  St  »•.  .  k^raKS  Bln^ral  acd  kjdrmt«<i  prKiwIpkMie  of  bos, 
v.v.  V /..^.t  ^^x.iSw  ia:/>  ike  v»mf^zid^z  soljikxtts:  uidm  msmUmt 
mAAi^".  y^*.  >  of  feandB.  prohar>iT.  icu>  K«date  of  borrta. 

^  Ts^  Cr..  ^yvir.;r  fi^N-taare*  take  ap  tke  wk*>:e  «f  tke  muimJ  atoai  of 
vxr/-«  fr'.-tt  It*  p^Toikle  of  kTdr.»e^ii.  wiik«>ai  eett^  aar  of  h  free,  and 
a/16  v.>T^nr  eMkrerted  iau)  the  f<riiowics'  eoiEpxiB«i5 :  Solpkaroiia  arid 
;av#  «r».:,^vrK  ^r.^  ;  a/|:ier,aj  aoiotKro  of  bvdr(>«iiipc(me  acid.  ek>wiT  into 
«»»r.  tw.pr.^r.  aCid  a  vety  fmall  qaaotitT  of  fvlpharie  acid;  aqaeotts 
krr  ;r/W,^  a<r.d  inUr  water  and  iodine  ;  karyta.  stTv>ctia  and  Kme  diaeolTed 
m  wtMr  tr.V/  the  er/rri^«p#ind:r.ir  kjdrmttf>d  peroxides,  wkick  are  preci|N* 
tMu4  ,  kjdmt/^  ffrfA/fXifU:  of  tin  into  bvdrate  of  tke  bi-oxide. 

la  ^/ynta^  Witk  v«>^e'<a^^l<  iiab«tai»ee«.  rack  as  oxalate  of  fwdaiwa, 
%^r^3a>.  fA  p^/tMiM,  aler/^K/l,  eampbor,  olive  oiL  aandaiac.  woodj  fibre, 
mjkf*^h,  mm,  tftrnwrn  mffAr,  Bianna-engar,  and  tndir^  tke  peroxide  of 
hyifi^*^  d/i^  WA,  erolre  oxT^ren  pereeptiblj  fibster  tkaa  wkea  kept  br 
itA^if  ^  »,«ki  t^^  fMy  at  lea«t  wben  starek  or  sugar  it  present^  is  nixed  witk 
^arv**k  ^  a/^  d. 

Yr*^  f//>.'/Wfnjr  art  destitute  of  decomposing  action: — AotimoBT.  tdl«- 
fi^m,  Un,  «Ad  iron  ;  alamrna,  niliea,  tnngstie  acid,  wMni-oxide  of  ckro- 
mr>'A,  *^*/pf  /#xfde  of  antimony,  antimonioiu  acid,  and  bi-oxide  of  tin; 
p4r/A|r^i«MA  /#f  iKida  ;  unlpbate  of  potassa,  soda^  baijta,  strontia  or  lime  ; 
ft^nmf  fMin^faJ  tnrf/iie,  chlorate  of  potasea ;  Ditraie  <^  potaasa,  ODd% 
\mf^t%,  ttf^/fjiia,  «/r  ox'uh  of  lead  ;  ebiohde  of  niie,  eorroaiTe  nblimate, 
w*4  ln^U\/,rifUi  f4  tin.  (Tb^nard.) 

/>/M///fi///i>>/nj,'--^.  Peroxide  of  kjdrogen  is  miaeible  in  all  propor- 
tf//A«  «rifh  waller,  fr^nn  this  mixtare  part  of  the  water  Ireeaes  oot  when 
0rtpf^*^4  Uf  f/fUL  The  name  eir«mniivtance8  wkick  indnoe  tke  deoompoei* 
t»//f»  f4  \mrn  tmrfft'ni^  of  bjdro^en,  likewiM  bring  abont  the  decomposition 
fff  that  whf^fi  iff  dilrjt^yl  with  water  ;  the  action  is,  howerer,  lees  riolent, 
n^*^  jiit»>n/le/|  witk  d#7irelopment  of  li;rht,  seldom  witk  evolution  of  keat, 
and  f«  ftf/i  ntf  n4f(fn  eompl^ted.  A  mixture  containing  eigkt  times  its  own 
fffhmf.  fff  ff%yi(Pin  ^an,  brains  to  erolre  gas  at  50"*  (122^  F.),  and  saboe- 
/|f##rrif  )y  fff^A  utUf  a  Mtate  of  violent  ebullition  ;  and  wben  tkis  kas  ceased, 
n*Mimtt  in  Mi  bnt  wat^rr.     (Tb^nard.) 

/a  VfToxUlit  fft  hydrogen  combines  with  hydrated  acids ;  e.  ff.  tke 
^f^fhfffir.f  fffilphnric,  hydrochloric,  hydrofluoric,  nitric,  oxalic,  citric,  and 
a^Mm  fU'UUf  forming  c</mpoands  in  which  it  is  less  easily  decomposible 
iban  wh#yn  abme.  In  thcNo  compounds,  the  acid  was  at  first  regarded  as 
«r«i«ilng  in  a  hiffber  state  of  oxidation.  The  comparatively  weak  cari>onie 
and  htfrn^tf  na'tnn  do  not  give  stability  to  peroxide  of  bydrogen.  The 
rtfmpffnnfU  fff  pf*roxide  of  hydrogen  with  acids  are  obtained  either  by 


acid  and  peroxide  of  hydrogen,  by  adding  to  it  the  silver-salt  of  that  acid 
whiek  is  to  b«  made  to  combine  with  the  peroxide  of  bydrogen.     The 


HYDROGBN-ACIDS.  79 

eyolation  of  ozjgen  gM  from  these  mixturea  takes  plaoe  less  easily  and 
more  slowly  than  from  the  pure  peroxide  of  hydrogen ;  but  when  the  aeid 
is  neutralised  by  an  alkali,  the  former  facility  of  decomposition  is  restored. 
The  greater  the  quantity  of  acid  mixed  with  the  peroxide,  the  more  does 
the  affinity  of  the  acid  for  that  compound  Interfere  with  its  decomposition 
by  elevation  of  temperature,  or  by  contact  with  most  of  the  bodies  above 
mentioned.  If  either  of  the  acids  just  enumerated  be  added  to  peroxide 
of  hydrogen  which  has  begun  to  e vol  ye  gas,  the  escape  of  gas  ceases  ;  it 
recommences  at  a  higher  temperature,  but  the  whole  of  the  oxygen  is  not 
driven  off,  even  by  half  an  hour's  boiling.  It  is  remarkable  that  although 
gold  decomposes  the  pure  peroxide  much  more  rapidly  than  bismuth  does, 
yet  the  quantity  of  acid  required  to  stop  the  action  of  the  sold  is  smaller 
than  that  which  must  be  added  to  prevent  the  action  of  the  bismuth. 
Peroxide  of  hydrogen,  brought  into  a  state  of  effervescence  by  gold,  pal- 
ladium, or  rhodium,  is  restored  to  tranquillity  by  the  addition  of  a  single 
drop  of  dilute  sulphuric  acid.  Ter-oxide  of  gold  liberates  oxygen  gas 
from  acidulated  peroxide  of  hydrogen,  and  is  itself  reduced,  first  to 
the  state  of  purple  oxide,  then  to  the  metallic  state.  In  the  nitric  acid 
compound  of  peroxide  of  hydrogen,  oxide  of  silver  is  reduced,  with 
evolution  of  oxygen  ;  but  part  of  the  oxide  dissolves  in  the  acid.  In  the 
hydrochloric  acid  compound,  the  oxide  of  silver  is  converted  into  a  violet- 
coloured  chloride  containing  less  than  one  atom  of  chlorine  for  each  atom 
of  silver.  Peroxide  of  manganese,  and  likewise  the  red  and  brown 
peroxides  of  lead,  liberate  oxygen  from  sulphate,  hydrochlorate,  or  nitrate 
of  peroxide  of  hydrogen,  and  at  the  same  time  give  up  part  of  their  own 
oxygen,  so  that  a  salt  of  protoxide  of  manganese  or  protoxide  of  lead  is 
formed.  In  these  acids  combined  with  peroxide  of  hydrogen,  many  metals 
dissolve  quietly,  taking  oxygen  from  the  peroxide,  thereby  converting  that 
componnd  into  water^  and  being  themselves  brought  to  the  state  of  oxides 
which  dissolve  in  the  acids.     (Th^nard.) 

C.  Suboxide  ofHydrogtn  f 

Water  absorbs  only  ^  of  its  bulk  of  hydrogen  gas,  according  to  W. 
Henry;  ^,  according  to  Dalton;  and  ^,  according  to  Saussure.  Paul, 
however,  asserts  that  by  strong  pressure,  1  volume  of  hydrogen  gas  may 
be  forced  into  3  volumes  of  water;  and  De  Marty  found  that  water  may, 
by  degrees,  be  made  to  take  up  a  greater  and  greater  quantity  of 
hydrogen  (the  quantity  taken  up  in  two  years  bein^  not  quite  equal  in 
volume  to  the  water  itself);  there  may  then  exist  a  suboxide  of  hydrogen, 
H*0.  This  compound  may,  according  to  Kastner  {Btrl,  Johrb.  1820, 
472),  be  obtained  by  repeatedly  saturating  water,  in  the  cold,  with 
hydrosulphuric  aeid,  and  then  removing  the  sulphur  by  means  of  certain 
metals. 

Qiher  Compounds  of  Hydrogen^ 

A.  Hydrogen  forms  10  inorganic  ffydj-ogm^eids,  or  Hydracids, 
namely,  the  Hydrosulphurous,  Hydrosnlphuric,  Hydro-sulpho-carbonic, 
Hydroselenic,  Hydriodous,  Hydriodic,  Hydrobromic,  Hydrochloric, 
Hydrofluoric,  and  Hydrotelluric  acids.  The  first  nine  may  be  called 
Mineral  or  Non-fnetallic  Hydrogen-acids,  and  thus  distinguished  from  the 
last,  which  is  a  Metallic  Hydrogen-acid^,    The  inorganic  hydracids  always 

*  Many  chemists,  in  accordance  with  the  idea  of  Sir  H.  Davy,  regard  the  hydrogen 
in  hydracids  as  the  addifiable  basis,  and  on  the  contrary,  the  snlphnr,  seleniam,  iodine, 
chlorine,  Ac,  as  the  addii^ring  principle— a  view  of  the  matter  which  appears  to  be 


80  HYDROGEN. 

oontain  one  atom  of  hydrogen,  and  one  atom,  rarely  more,  of  the  acid- 
radical. 

Respecting  the  action  of  hjdrogen-acids  on  salifiable  metallic  oxides, 
two  views  are  entertained  (yid,  pp.10....  13).  According  to  the  second 
of  these  views,  they  form  hydrogen-salts ;  according  to  the  first,  double 
decomposition  takes  place,  and  the  metal  combines  with  the  radical  of 
the  acid,  (a.^  When  a  hydrogen  acid  comes  in  contact  with  a  metallic 
oxide,  in  sucn  proportion  that  the  hydrogen  of  the  acid  exactly  corre- 
sponds with  the  oxygen  of  the  oxide — ^then,  according  to  the  second  view, 
a  normal  hydrogen-salt  is  formed :  e.  g.  KO,  HS  and  SnO',  2HS;  according 
to  the  first  view,  the  elements  interchange  in  snch  a  manner  as  to  form 
water,  and  a  compoand  of  the  metal  with  the  radical  of  the  acid :  e,  g. 
KS  +  HO  and  SnS'  +  2H0.  (b.)  If  the  number  of  atoms  of  hydrogen  in 
the  hydracid  exceeds  the  num1)er  of  atoms  of  oxygen  in  the  oxide,  then, 
according  to  the  second  view,  an  acid  hydrogen-salt  is  formed :  e.  g, 
KO,  2HS;  according  to  the  first  view,  there  is  produced,  besides  water, 
a  compound  of  the  metal  with  part  of  the  radical  of  the  acid,  and  this 
compound  enters  into  comhination  with  the  rest  of  the  hydracid :  t,  g, 
KS,  HS  +  HO.  (c.)  When  the  number  of  atoms  of  oxygen  in  the 
metallic  oxide  is  greater  than  the  number  of  atoms  of  hydrogen  in  the 
hydracid,  a  basic  hydrogen-salt  is  formed,  according  to  the  second  view : 
t,  g,  4CuO,  HCl  +  SAg;  according  to  the  first  view,  water  is  produced, 
and  likewise  a  compound  of  the  metal  with  the  radical  of  the  acid,  and 
with  this  compound  the  undecomposed  portion  of  the  metallic  oxide 
enters  into  com  oi  nation :  t,  g.  3CuO,  CuCl  +  4Ag. 

B.  Hydrogen  forms  one  salifiable  base,  viz.  Ammonia, 

C.  The  remaining  inorganic  compounds  of  hydrogen  take  the  form 
either  of  combustible  gases,  as  Phosphuretted,  Arseniuretted,  and  Anti- 
moniuretted  Hydrogen  gas,  or  of  solid  bodies,  as  Hydride  of  Potassium, 
and  Hydride  of  Arsenic. 

In  the  ffaseous  compounds  of  hydrogen,  the  following  relations  of 
volume  are  found :  (a.)  One  volume  of  the  stronger  hydracids  contains  half 
a  volume  of  hydrogen  gas  :  HF,  HCl,  HBr,  HI.  (6.)  One  volume  of  the 
weaker  hydracids  contains  1  volume  of  hydrogen  gas :  HS,  HSe,  HTe. 
(c.)  One  volume  of  those  hydrogen  compounds,  which  are  more  or  less 
basic,  contains  1^  volumes  of  hydrogen  gas:  NH',  PH',  AsH*.     (I.,  QQ,) 

D.  Hydrogen  forms  an  essential  constituent  of  nearly  all  organic 
compounos. 

Banctioned  by  the  electro-chemial  theory.  Since,  however,  sulplmr,  seleniom,  ioiine, 
chlorine,  &c.,  are  not  capable  of  forming  well-defined  adda  with  any  snbstonoe  excepting 
hydrogen  or  oxygen  (p.  3),--for  the&ct  that  phosgene  and  pentachloride  of  phosphorus 
have  been  observed  to  redden  litmus  may  be  attributed  to  the  presence  of  a  trace  of 
water, — and  since  hydrosulphuric  and  hydriodic  adds  possess  stronger  acid  properties 
than  the  hydrosulphurous  and  hydriodons,  which  contain  less  hydrogen  in  proportion,  it 
appears  to  me  to  be  simpler  to  seek  the  cause  of  the  acid  nature  of  the  compounds  in 
question  in  the  hydrogen  which  they  contain. 


CAKBON.  81 

Chapter  III. 

CARBON. 


LaToisier.     Fonnatioii  of  Carbonic  acid.     CrelL  Ann.  1788.     1,  552; 

2,  55. 
Cniikshank.     Compounds    of   Hydrogen    and    Oxjgen    with    Carbon. 

Scher.  J.  7,  371. 
Tennant.     Nature  of  the  Diamond.     Scher,  J,  2,  287. 
Mackenzie.     Combustion  of  the  Diamond.     Seher.  «/.  7,  362. 
Allen  &  Pepys.     Carbonic  acid  and  Diamond.     N,  Gehl,  5,  664. 
Theod.  de  Saussure.     Combustion  of  Charcoal.     Ann,  Chim.  71«  254. 
Guyton-Morveau.     Combustion  of  the  Diamond.     Ann,  Chim,  84,  20, 

and  233. 
Sir  Humphry  Davy.     Diamond,  Graphite,  and  Charcoal.     Phil,  Trans. 

1809,  I.,  69;  Schw.  2,  42;  also  GUb.  35,  433. 
— — ^ Combustion  of  the  Diamond  and  Charcoal.     FhU, 

Trans.  1814,  II.,  557;  S<^w.  12,  200;  also  Oilb.  49,  1. 
Silliman.     Fusion  of  Carbon.     Sill,  Am,  J,  5,  361;  also  Schw,  39,  190. 

SUl,  Am.  J.  6,  341;  also  Schw.  39,  87.    Ann.  PhU,  22,  311  and 

468.     SUl.  Am,  J,  10,  119. 
Berzelius.     Atomic    Weight  of   Carbon.    Pogg,   47,  199;    also    Ann. 

Pharm.  30,  241. 
Dumas  &  Stas.     Diamond,  Plumbago,   Atomic  Weight.     Ann,   Chim, 

Phys.  76,  1 ;  also  Ann.  Pharm.  38,  141;  also  J.  pr,  Chem,  22,  300. 
Erdmann  &  Marchand.     Diamond,  Plumbago,  Atomic  Weight.     J,  pr. 

Chem.  23,  159. 
Liebig  &  Redtenbacher.      Atomic  Weight  of  Carbon.      Ann.  Pharm. 

38....113. 

Carbonic  Oxide. 

Desormes  &  Clement.     Carbonic  oxide.      GUb.    9,  409;  also  Scher.  J. 

7,  327;  also  CreU,  Ann.  1801,  2,  318,  415,  and  474. 
Deiman,  Pats  Van  Troostwyk  &  Lauwerenburgh.     Scher,  J.  9,  261 ;  also 

CreU.  Ann.  1802,  2,  26. 
Th.  Saussure.     GUb.  13,  138. 
Fownes.     Action  of  Oil  of  Vitriol  upon  Ferrocyanide  of  Potassium. 

PhU,  Mag,  J,  24,  21 ;  also  Manual  of  Chemistry,  2nd  Ed.  p.  24. 

Carbonic  Acid. 

Black.     Medical  and  PhUos.  Ccmm.,  by  a  Society  in  Edinburgh, 

Bergman.     Opusc,     1,  1. 

Priestley.    Experiments  and  Observations  on  diferent  Kinds   of  Air. 

1,  43. 
Thilorier.     Ann.  Chim.  Phys,  60,  427 ;  also  Pogg.  36,  141.     Further; 

Ann.  Pharm,  30,  122. 


Carbons,  Carbonium,  Kohlenstof, 

History,     The  eyolution  of  carbonic  acid  gas  in  the  burning  of  lime 
and  in  fermentation  was  known  to  Paracelsus  and  Van  Hefanont ;  snbse* 

VOL.   IT.  o 


8?  CARBON. 

qnently,  the  properties  of  this  gas  were  investigated  bj  Hales,  Blacky 
Priestley,  and  Bergman.  Lavoisier  showed  that  it  is  composed  of  oxygen 
and  another  substance,  Carbouy  which  he  himself  first  proved  to  oe  a 
distinct  element.  He  likewise  showed  that  this  element  exists  in  a  state 
of  pnritj  in  the  diamond,  the  volatilization  of  which  in  the  focus  of  a 
burning  mirror  had  been  observed  by  the  Florentine  academicians  in 
1694.  Lavoisier^s  statement,  that  the  diamond  when  burnt  is  converted 
into  carbonic  acid,  was  confirmed  by  Smithson,  Tennant,  Mackenzie, 
Allen  &  Pepys,  Morveau,  Saussure,  Sir  H.  Davy,  Dumas  &  Stas, 
Erdmann  &  Marchand,  aud  others.  Lassonne  (Crell,  N,  Entdeck,  2, 
144),  Priestley  {Crell.  Ann.  1800,  2,  256),  and  Woodhouse  {Gilb.  9, 
90),  discovered  carbonic  oxide  gas.  Priestley  regarded  the  production  of 
this  combustible  gas,  in  the  perfect  absence  of  water,  as  contradictory  to 
the  theory  of  Lavoisier :  but,  on  the  other  hand,  it  was  shown  by  Cruik- 
shank,  Morveau,  Clement  &  Desormea,  Fourcroy  &  Th^nard  (GUb. 
9,  99;  also  Scker.  J.  7,  224),  W.  Henry,  Dalton,  and  Gay-Lussac  & 
Tbenard,  that  this  gas  does  not  contain  hydrogen,  but  consists  wholly  of 
carbon  and  oxygen, 

Sources.  Pure  in  the  diamond;  mixed  with  iron,  earthy  matters, 
hydrogen,  &c.,  in  graphite  or  plumbago  and  anthracite;  in  the  form 
of  carbonic  acid;  and  finally,  in  all  organic  bodies.  The  Diamond 
is  probably  carbon  which  has  been  fused  at  a  high  temperature  and 
crystallized  bjr  slow  cooling :  thus,  Gbbel  {Pogg.  20,  539)  is  of 
opinion  that  it  is  carbon  reduced  from  carbonate  of  lime  by  some 
of  the  earth-metals  at  high  temperatures.  According  to  another  view, 
diamond  is  carbon  separated  from  decomposing  organic  compounds. 
Perfectly  pure  diamond  would  probably  burn  without  residue ;  impure 
diamona  leaves  at  least  0  05,  and  at  most  0*2  per  cent,  of  ash,  sometimea 
in  the  form  of  a  reddish-yellow  powder,  sometimes  in  straw-yellow 
crystalline  particles.  (Dumas  &  Stas.)  Transparent  diamonds  leave 
scarcely  any  ash;  those  which  are  more  or  less  opaque  leave  from  0*08 
to  0*15  per  cent,  of  reddish  ash.  (Erdmann  &  Marchand.)  This  ash, 
when  examined  by  the  microscope,  appears  to  consist  of  laminaa  and 
spicnlsD,  intermixed  with  a  few  roundish  granules,  some  of  the  particles 
being  black,  opaque,  and  possessed  of  very  strong  lustre ;  some,  brown- 
black  and  translucent;  others  yellowish-orown,  yellow,  or  white,  and 
transparent.  They  mostly  exhibit  a  peculiar  structure,  sometimes  that  of 
dark-brown  network,  like  vegetable  parenchyma.  The  ash  contains 
silica  and  iron.  (Petzholdt,  J.  pr.  Chem.  28,  475.)  Nearly  all  diamonds 
when  examined  by  the  microscope,  exhibit  coloured  portions  in  the  form 
of  roundish  patches  or  clouds,  in  which  no  trace  of  organic  structure  can 
be  discerned.  In  green  diamonds,  the  deep  emerald  green  parts  become 
brown  and  black  by  ignition ;  but  the  colour  of  brown  diamonds  is  not 
altered  by  the  same  treatment.     (Wbbler,  Ann,  Pharm.  41,  346.) 

Graphite  from  Wunsiedel  yields  only  0*33  per  cent,  of  ash,  consisting 
of  potassa,  silica,  and  oxide  of  iron  :  it  is  therefore  nearly  pure  carbon. 
(Fuchs.)  Graphite  from  Germany,  specific  gravity=2'273,  contains 
95*12  per  cent,  of  carbon,  and  5*73  per  cent,  of  ash,  chiefly  consisting  of 
grains  of  quartz.  (Regnault,  Ann,  Chim.  Phys.  66,  337.)  Graphite 
from  Bustletown,  contains  95*4  per  cent,  of  carbon,  0*6  of  water,  and  4*0  of 
silica,  alumina,  and  the  oxides  of  iron  and  manganese.  (Vauuxen, 
IXU,  Am.  J.  10,  102.)  The  purest  graphite  from  Ceylon  yields  only 
1  '2  per  cent,  of  ash ;  other  varieties  6  per  cent.,  consisting  of  oxide  of  iron 


CARBON.  83 

and  eariby  matters.  Grapbite  from  the  Himala3ra  moctntaina  oontaiiu 
only  71*6^  and  English  graphite  only  53*4  per  cent,  of  carbon^  together 
with  iron  and  large  quantities  of  silica  and  alumina.  (Prinsep^  N,  Ed. 
Phil,  J,  18,  346.)  According  to  Morveau,  Davy,  and  Gay-Lussac  Bt 
Th^nard,  graphite  contains  a  small  quantity  of  hydrogen;  according  to 
Allen  &  Pepys  and  Saussure,  it  contains  none  of  that  element.  Anthra-' 
cite  closely  resembles  charcoal  from  organic  bodies,  and  contains  essentially 
—  besides  carbon  and  ash  —  from  1*5  to  4  per  cent,  of  hydrogen^ 
generally  associated  with  oxygen  and  nitrogen  in  smaller  quantity. 

Preparation,     1.  Artificud  Grapkiie.     (a,)  Crude  cast-iron  as  it  flows 

from  the  blast-furnace,  highly  charged  with  carbon,  deposits,  on  solidi- 

fying,  a  portion  of  the  dissolved  carbon    in  metallic-shining  laminss  of 

graphite.     (6.)  Graphite  in  a  similar  state  is  obtained  when  a  mixture  of 

2  parts  of  iron  filings,  1  part  of  black  oxide  of  manganese,  and  1  part  of 

lamp  black,  is  heated  to  whiteness  in  a  crucible.     (Ddbereiner,  Schw. 

16,  97.)     To  purify  both  the  graphite  of  the  blast-furnaces  (a)  and 

likewise  native  graphito,  from  iron  and  earthy  matters,  Dumas  <fe  Stas 

ignite  the  substance  in  the  state  of  powder  in  contact  with  hydrate  of 

potassa — ^wash  the  ignited  mass  with  water— exhaust  it  with  boiling  aqua 

regia — ^then,  after  washing  and  drying  the  residue,  subject  it  at  a  white 

heat  for  18  hours  to  a  current  of  dry  chlorine  gas :  by  this  means,  small 

quantities  of  chloride  of  iron  and  chloride  of  silicium,  not  removed  by 

the  aqua  regia,  are  sublimed.     In  this  state,  the  graphite  is  quite  free 

from  hydrogen,  and  when  burnt,  leaves  either  no  residue  or  a  mere  trace 

of  silica.     Ceylon  graphite,  purified  in  this  manner,  was  found  by  Erd- 

mann    8c    Marchaiid    to  yield,   on  burning,   0*5   per  cent,    of    silica. 

Ddbereiner  purifies  the  graphite  (6)  by  exhausting  it  with  boiling  aqua 

regia.     According  to   Gay-Lussac  {Ann.  Chim,  Phyt.  4,  69),  graphite 

thus  purified  still  contains  iron.     The  silica  contained  in  graphite  may 

likewise  be  removed  by  means  of  hydrofluoric  acid.     (Schaphtlntl,  J,  pr« 

Chem.  19,  139.)     When  cast-iron,  intersected  with  laminae  of  graphite, 

is  dissolved  in  aqua  regia,  the  graphite  remains  behind  mixed  with 

gelatinous  silica;  and  when  the  latter  is  removed  by  solution  in  caustie 

potassa  and    repeated   boiling  with  water,   there  remains  a  kind  of 

graphite,  which  when  burnt  leaves  2*6  per  cent,  of  white  ash.     When 

cast-iron  of  this  description  is  melted  in  a  crucible,  the  iron  runs  off 

from  the  graphite,  and  the  laminae  of  that  substance  may  be  separated 

from  iron  still  adhering  to   them,  by  reducing  them  to  powder,  and 

removing  the  iron  by  a  magnet :  in  this  manner,  without  the  use  of  acid, 

the  iron  may  be  almost  wholly  removed.     It  appears  then  that  iron  is 

not,   as  was  formerly  supposed,  an  essential  constituent  of  graphite. 

iSefstrftm,  Pogg.  16,  168.)  Karsten  examined  a  specimen  of  graphite 
rom  a  blast-furnace,  of  specific  gravity  2  3285,  and  found  it  to  bum 
without  residue.  A  specimen  examined  by  Wollaston  contained  manga* 
nese ;  one  examined  by  the  author  left,  on  being  burnt,  a  white  residue^ 
which  exhibited  the  properties  of  silica. 

2.  Charcoal,  This  form  of  carbon  is  obtained  by  strongly  igniting  in  a 
covered  vessel  such  non-azotized  organic  compounds  as,  on  burning; 
leave  no  fixed  residue ;  e.  g.  pure  sugar — or  by  passing  the  vapours  of 
volatile  organic  compounds,  such  as  alcohol,  ether,  volatile  or  fat  oil^ 
through  white-hot  porcelain  tubes.  Charcoal  from  sugar,  even  after 
being  heated  to  whiteness,  still  contains  0-6  per  cent,  of  hydrogen,  and 
3-1  per  cent  of  oxygen;  and  after  further  ignition  for  three  hours  in  the 

o  2 


84  CARBON. 

strongest  blast-farnace^  there  yet  remains  0*2  per  cent,  of  hydrogen^  and 
0*5  per  cent,  of  oxygen. 

Under  certain  circamstances^  a  kind  of  carbon,  free  from  hydrogen^ 
and  similar  to  graphite,  appears  to  separate  from  organic  compounds. 

1.  In  porcelain-furnaces,  which  have  not  a  good  draught,  carbon  free  from 
hydrogen  is  deposited  in  long,  thin,  dark-grey,  non-crystalline  threads, 
some  straight,  and  some  ramified,  and  exhibiting  metallic  lustre  when 
examined  by  the  microscope.      (Gay-Lussac,  Ann.  Chan,  Pkys,  4,  67.) 

2.  Gas-coke.  When  coals  are  heated  to  redness  in  cast-iron  gas-retorts,  a 
quantity  of  carbon,  free  from  iron  and  hydrogen,  is  deposited  upon  the 
upper  parts  and  in  the  necks  of  the  retorts,  forming  a  hard,  slaty 
substance  of  an  iron-grey  colour;  also  on  cracks  in  the  retorts,  in  the 
form  of  a  warty  mass,  exhibiting  a  concentric  and  radiating  structure. 
(Colquhoun.)  In  the  preparation  of  steel  by  Makintosh's  process,  coal- 
gas  is  passed  over  red-hot  iron  bars  contained  in  earthen  vessels :  if  the 
gas  is  supplied  so  rapidly  that  the  iron  cannot  take  up  the  whole  of  its 
carbon,  the  excess  of  carbon  is  deposited  in  one  of  the  three  following 
forms :  a.  In  metallic-shining,  hard,  dense  masses  of  conchoidal  fracture, 
scarcely  to  be  scratched  with  a  penknife,  h.  As  a  fine  powder,  similar 
to  lamp-black,  but  heavier  and  of  coarser  grain.  These  two  kinds  cover 
the  steel,  and  upon  them  is  deposited:  c.  Carbon,  in  black,  metallic- 
shining,  capillary,  and  somewhat  brittle  threads,  thousands  of  which  are 
united  like  locks  of  hair:  they  are  not  combustible  in  the  flame  of  a 
candle^  but  perfectly  so  in  the  blow-pipe  flame.  (Colquhoun,  Ann,  Phil. 
28,  1;  also  Kastn,  Arch.  9,  87;  also  Br.  Arcfi.  23,  10;  Braylay,  Ann. 
FhU,  28,  192;  also  Br.  Ardi,  23,  15.)  When  oil-gas  is  passed  over 
white-hot  iron  wire  contained  in  a  porcelain  tube,  the  iron  is  converted 
into  steel,  and  becomes  coated  with  brittle  graphite,  containing  2  per 
cent,  of  iron ;  but  at  the  same  time  there  is  deposited  in  the  tube  an 
elastic,  brittle  kind  of  graphite^  which  burns  slowly,  but  without  residue. 
(Sefstrom.) 

Cagniard  de  la  Tour's  Artificial  Diamond  is  charcoal,  intimately 
mixed  with  a  hard,  crystalline  slag,  containing  alumina  and  sesqui-oxide 
of  iron,  together  with  silica  and  sesqui-oxide  of  manganese.  (Th^nard, 
J.  Ohim,  Med.  5,  38  and  39,  also  rogg.  14,  525.)  (GannaFs  so-called 
Artificial  Diamond,  J.  Chim.  Med.  4,  382;  also  Pogg,  14,  387;  15,  311.) 

Propertiet.  The  Diam/>nd  crystallizes  in  regular  octohedrons  and 
their  modifications  {fig.  2,  6,  8,  and  others);  it  is  generally  colourless 
and  transparent,  of  extreme  hardness,  peculiar  lustre,  very  high  refracting 
power,  and  is  a  non-conductor  of  electricity.  Native  Graphite,  Plumbago^ 
or  Black  Lead,  cnrstallizes  in  hexagonal  tables  of  specific  gravity  2' 14 
according  to  Fuchs,  and  2*273  according  to  Regnault:  it  is  steel-grey, 
soft,  greasy  to  the  touch,  leaving  a  mark  when  rubbed  on  other  bodies, 
and  is  a  very  good  conductor  of  electricity.  Artificial  graphite  possesses 
similar  properties.  Charcoal  obtained  by  the  ignition  of  organic  sub- 
stances, as  well  as  that  produced  from  the  decomposition  of  carbonic  acid, 
is  an  amorphous  substance,  of  specific  gravity  about  1  *57,  opaque,  blacky 
often  possessed  of  metallic  lustre,  soft  (but  becoming,  after  intense 
iffnition,  hard  enough  to  scratch  glass),  and  a  very  good  conductor  of 
electricity.  Carbon  in  all  its  forms  is  one  of  the  most  difficult  of  all 
bodies  to  fuse  or  volatilize;  it  is  also  destitute  of  taste  and  smell. 

The  great  difference  between  diamond,  on  the  one  hand,  and  graphite, 
or  charcoal,  on  the  other,  is  commonly  attributed,  partly  to  the  different 


CARBON.  85 

degrees  of  purity  of  the  carbon  in  these  several  forms,  partly  to  differ- 
ences in  the  state  of  aggregation  of  its  atoms.  The  former  of  these 
explanations  can  only  apply,  in  a  certain  degree,  to  charcoal,  inasmuch 
as  that  substance  generally  retains  small  quantities  of  hydrogen  and 
oxygen;  but  diamond  and  perfectly  pure  graphite  consist  wholly  of 
carbon.  The  second  explanation  must  therefore  be  resorted  to  in  aid  of 
the  first.  According  to  the  latter,  carbon  in  diamond  belongs  to  the 
regular  crystalline  system;  in  graphite  to  the  rhombohedral  system;  in 
charcoal  it  is  amorphous.  Fuchs  (J.  pr.  Chem.  7,  353)  regards  graphite 
as  amorphous,  like  charcoal,  and  supposes  that  the  crystals  of  native 
graphite  are  pseudo-morphous  crystals,  formed  from  those  of  mica  or 
sulphide  of  molybdenum.  At  all  events,  graphite  and  charcoal  are  much 
more  nearly  allied  than  diamond  and  graphite:  the  specific  gravity  of 
graphite  is,  however,  greater  than  that  of  charcoal,  and  the  crystallization 
of  artificial  graphite  appears  to  be  established  beyond  doubt.  Still,  how- 
ever, it  is  extremely  difficult  to  understand  how  dimorphism  and  amor- 
phism  should  give  rise  to  these  marked  diversities  in  the  characters  of  a 
substance.  In  no  other  body  are  such  decided  differences  produced  by 
the  same  causes.  Carbon  in  the  diamond  is  transparent  and  a  non- 
conductor of  electricity,  like  the  other  non-metallic  elements;  but  in 
graphite  and  charcoal  it  is  opaque,  possessed  of  metallic  lustre,  and  a 
good  conductor  of  electricity — and  consequently  approaches  nearer  to  the 
metals :  hence  Dbbereiner  designated  graphite  as  a  metal,  Carbonium, 

A  diamond  placed  on  a  support  of  lime  or  plumbago,  and  exposed  to 
the  flame  of  a  powerful  oxy-hydrogen  blow-pipe,  bums  quickly  away. 
The  unconsumed  portion  is  found  to  be  rounded  at  the  comers,  and 
roughened  on  the  surface ;  it  has  also  lost  much  of  its  lustre,  and  exhibits 
numerous  cracks,  corresponding  to  the  planes  of  cleavage.  Whether 
superficial  fusion  takes  place  under  these  circumstances,  is  a  point  not  yet 
decided.  When  graphite  is  heated  in  the  oxy-hydrogen  flame,  a  portion 
bums  away,  and  a  great  number  of  fused  globules  are  obtained,  which 
are  non-conductors  of  electricity,  hard  enough  to  scratch  glass;  some 
black,  and  affected  by  the  magnet ;  others  colourless,  transparent,  and 
non-magnetic.  Anthracite  yields  similar  transparent  globules.  ^Silliman.) 
Diamond  exposed  on  magnesia  to  the  oxy-hydrogen  blow-pipe,  turns 
black,  and  splits  into  pieces  exhibiting  conchoidal  fracture;  when  heated 
on  pipe-clay,  it  exhibits  numerous  incisions,  and  appears  to  undergo 
partial  fusion.  (Murray,  Ann.  Fhil,  22,  469.)  When  a  diamond  is 
heated  in  the  oxy-hydrogen  flame  till  the  greater  part  is  burnt  away,  the 
remaining  portion  is  found  to  have  its  angles  melted  off,  and  appears  half 
fused.     (Marx,  Schw.  47,  324.) 

IT  The  diamond,  when  exposed  to  a  very  high  temperature  produced 
by  a  Bunsen's  battery  of  100  plates,  or  by  a  condensed  mixture  of  carbonic 
oxide  and  oxygen  gas,  fuses,  and  is  converted  into  a  mass  resembling 
coke;  its  specific  gravity  is  thereby  reduced  from  3*336  to  2*678.  (Jac- 
quelin,  N,  Ann.  Chim,  Phys.  20,  459.)  IT 

On  attaching  to  the  polar  wires  ot  a  deflagrator  ^I.,  409)  a  couple  of 
flexible  leaden  tubes — ^inserting  into  these  tubes  two  cylmders  of  mahogany- 
charcoal,  well  boiled  in  water,  from  1^  to  3  inches  long,  \  an  inch  thick, 
and  pointed  in  front — bringing  these  cylinders  in  contact,  whereby  they 
are  Drought  to  a  state  of  vivid  incandescence,  and  then  separating  the 
points  by  a  short  distance,  they  continue  to  elow  vividly,  form  between 
them  a  bright  luminous  arc  of  flame,  and  send  up  a  white  smoke  having 
a  peculiar  odour,  like  that  of  an  electrical  machine  in  strong  action.     On 


86  CARBON. 

the  Ghareoal  point  of  the  zinc  pole  (from  which  the  negative  eloctriciij 
issaes)  there  is  deposited — while  the  cylinder  decreases  on  its  sides — 
a  quantity  of  additional  matter,  which  grows  to  the  length  of  half  an 
inch,  then  breaks  off,  and  is  replaced  by  a  new  growth :  on  the  contrary, 
the  charcoal  of  the  positive  pole,  from  which  the  positive  electricity  issues, 
soon  loses  its  point,  and  a  cup-like  cavity  is  formed  in  it,  whilst  at  the 
same  time  it  suffers  but  little  diminution  on  the  sides.  To  whichever 
part  of  the  positive  charcoal  the  point  of  the  negative  piece  is  directed, 
there  the  excavation  is  produced.  If  the  two  pieces  of  charcoal  come  in 
contact,  they  stick  together.  If  the  positive  charcoal  be  replaced  by  a 
piece  of  metia.1,  the  negative  piece  receives  no  increase,  but  is  gradually 
shortened  during  the  combustion.  In  nitrogen  gas,  the  two  pieces  of 
charcoal  exhibit  as  brilliant  a  light,  and  the  same  growth  of  the  negative 
point,  as  in  air.  Hence  it  appears  that  carbon,  in  the  state  of  vaponr,  is 
transferred  from  the  positive  to  the  negative  pole.  If  the  eyes  are  pro- 
tected by  a  pair  of  green  spectacles,  small  particles  of  carbon  may  even 
be  seen  passing  along  the  luminous  arc  from  the  copper  pole  to  the  zinc 
pole.  The  matter  which  accumulates  on  the  negative  point  sometimes 
forms  a  cylinder,  sometimes  a  round  knob  with  a  stem.  When  examined 
by  a  magnifying-glass,  it  exhibits  a  fused,  warty  or  botremous,  smooth, 
metallic-shining,  greyish-black  surface,  and  a  non-fibrous  structure;  sinks 
rapidly  in  oil  of  vitriol;  does  not  conduct  electricity  (hence  its  presence 
makes  the  charcoal  less  brightly  incandescent — but  on  the  removal  of  the 
fused  portion,  the  brightness  is  restored);  burns  very  slowly  at  a  red 
heat,  without  visible  flame,  producing  carbonic  acid,  and  leaving,  some- 
times a  yellowish-grey  ash,  sometimes  none  at  all.  It  is  not  attacked  by 
oil  of  vitriol,  and  very  little  by  hot  nitric  acid.  No  sign  of  fusion  ever 
appears  on  the  positive  charcoal.  (Hare,  Silliman.)  The  same  result 
was  obtained  by  Griscom  (Ann.  Phil.  22,  73^,  and  even  with  an  ordinary 
voltaic  battery.  (West,  Ann.  Phil.  21,  314.)  When  cylinders  of  maple- 
wood-charcoaJ,  well  boiled  in  hydrochloric  acid  and  water  and  then 
strongly  ignited,  are  subjected  to  the  action  of  a  powerful  deflagrator, 
they  instantly  melt  at  their  points  to  a  vitreous  mass,  and  likewise  exhibit 
a  depression  on  the  copper  and  a  cylindrical  growth  on  the  zinc  side. 
Moreover,  the  copper  charcoal  always  diminishes  in  weight:  the  zinc 
charcoal  sometimes  increases,  especially  when  the  experiment  is  made  in 
a  glass  tube;  sometimes  remains  of  constant  weight,  and  sometimes  dimi- 
nishes, though  much  less  than  the  charcoal  connected  with  the  copper 
pole.     (Silliman.) 

If  a  cylinder  of  graphite  an  inch  long,  \  of  an  inch  thick,  and  pointed 
at  the  end,  is  attached  to  the  copper  pole,  and  a  piece  of  wood-charcoal 
to  the  zinc  pole,  the  graphite  becomes  partly  red  hot ;  and  on  the  edge  of 
the  ignited  point,  where  also  an  emission  of  sparks  takes  place,  globules 
of  fused  graphite  are  continually  formed :  in  the  space  between  the  two 
points,  which  is  filled  with  vapour  of  carbon,  no  sparkling  takes  place. 
At  the  point  of  the  graphite,  a  black  shining  hollow  is  produced.  On 
the  other  hand,  the  charcoal  at  the  zinc  pole  becomes  elongated,  from  the 
deposition  of  a  fused  mass,  not  in  globules,  but  of  a  fibrous  structure. 
Besides  this,  there  are  likewise  globules  formed  upon  it;  and  when  the 
two  points  are  placed  in  a  vertical  line,  the  graphite  being  uppermost,  no 
frlobules  are  formed  upon  the  latter,  but  a  proportionally  greater  number 
(mostly  black  ones)  on  the  charcoal  point  below.  Similar  effects  are 
produced  when  the  charcoal  is  connected  with  the  copper,  and  the  graphite 
with  the  zinc  pole;  or  again,  when  graphite  or  charcoal  is  placed  upon 


CARBONIC  OXID£.  67 

both  poles.  When  the  graphite  is  connected  with  the  sine  po]e^  it  either 
retains  it  weight  unaltered,  or  increases  in  weight,  by  covering  itself  with 
fused  carbon,  as  much  as  the  charcoal  connected  with  the  copper  pole 
diminishes.  The  globules  on  the  charcoal  are  shining,  rarely  black,  more 
frequently  brown,  yellow,  greyish-white,  or  sometimes  quite  colourless, 
and  at  the  same  time  either  slightly  cloudy  or  quite  transparent.  Most  of 
them,  when  examined  by  the  microscope,  appear  to  be  quite  free  from 
any  admixture  of  charcoal.  The  graphite  globules  are  almost  always 
black  (never  colourless).  They  scratch  glass,  and  are  non-conductors  of 
electricity.  The  coloured  ones  only  are  slightly  attracted  by  the  magnet 
(because  they  contain  iron).  They  are  extremely  difficult  to  burn:  when 
iguited  with  chlorate  of  potassa,  they  yield  large  quantities  of  carbonic 
acid.  They  constitute,  therefore,  a  form  of  caroon  closely  allied  to  the 
diamond.  (Silliman*)  The  globules,  when  burnt  in  the  oxy-hydrogen 
flame,  leave  but  very  little  residue :  when  strongly  heated  with  nitre  they 
detonate,  and  form  carbonate  of  potassa,  with  which  there  is  mixed  a 
small  quantity  of  peroxide  of  iron.  Hence  they  consist  of  carbon,  with 
a  very  small  quantity  of  iron.     (Hare,  Sill.  Am.  J,  10,  110.) 

According  to  Vanuxen  (Schto.  43,  253;  SUl.  Am.  J.  10,  102),  on  the 
contrary,  these  globules  are  nothing  but  the  fused  ashes  of  the  charcoal 
and  graphite,  and  consist  mainly  of  iron  and  silica.  Vanuxen  likewise 
showed  that  graphite,  anthracite,  and  mahogany-charcoal,  when  heated 
by  the  oxy-hydrogen  blow-pipe,  yield  a  greater  number  of  globules,  both 
of  the  colourless  and  non-magnetic,  and  the  black  and  ma^etic  variety, 
in  proportion  as  they  contain  more  ash;  whereas  lamp-black,  pressed 
together  into  the  form  of  a  cylinder,  and  containing  only  ^^  of  Its  weight 
of  ash,  yields  no  globules.  On  the  other  hand.  Hare  has  defended  his 
opinion  in  the  Philosophical  Magazine^  65,  283;  and  in  SiUimarC 9  Journal, 
10,  110,  he  maintains  that  the  oxy-hydrogen  blow-pipe  is  not  adapted  for 
the  fusion  of  carbon,  inasmuch  as  the  oxygen  bums  the  carbon,  and  leaves 
nothing  but  the  fused  ash.  It  is  greatly  to  be  regretted  that  Hare  and 
Silliman,  in  their  experiments,  did  not  select  a  kind  of  cbairooal  which 
does  not  leave  any  ash. 

Atomic  weight  of  Carbon :  6,  according  to  Damas  8c  Stas,  ErdmaiiD 
&Marchand;  6,06832^  according  to  Liebig  d;  Redtenbacher;  6*18,  accord- 
ing to  Berzelins. 

Compounds  of  Carbon, 

Carbon    and    Oxygbn. 

The  affinity  of  carbon  for  oxygen  is  one  of  the  most  poworfnl  in 
existence. 

A.    Carbonic  Oxtdb.    CO. 

Carbonic  acid  gat,  Oomoxu  Oxide  of  carbon^  Carbonom  acid  gas;  incor- 
rectly :  Oxidated  CarburetUd  Hydrogen  gas,  Oas  hydrogine  oxyoarburi. 

Found,  together  with  carbonic  acid  gas,  in  the  intestinal  canal  of 
hooved  cattle.     (PflUger,  Kastn.  Arch.  9,  98.) 

Formation,  1.  When  bodies  which  retain  oxygen  with  a  certain 
degree  of  force  are  ignited  with  charcoal  or  plumbago. — ^When  vapour 
of  water  is  passed  over  wcU-bumt  charcoal  kept  at  a  red  heat  in  a  por- 


88  CARBON. 

celain  tabe,  {App.  9.),  decomposition  takes  place,  and  hjdrogen,  carbonic 
oxide,  and  carbonic  acid  gas  are  produced  (Clement  &  Desormes, 
GUb.  9,  423).  100  volnmes  of  the  gaseous  mixture  thus  obtained  contain 
56'21  hydrogen  g2LB,  28*96  carbonic  oxide,  14-63  carbonic  acid,  and  0'19 
marsh  gas ;  therefore  exactly  2  atoms  of  carbonic  oxide  to  1  atom  of 
carbonic  acid :  this,  however,  is  perhaps  accidental.  When  common  char- 
coal  not  preyiouslj  ignited  is  used,  the  gaseous  mixture  contains  7 '55 
measures  of  marsh-gas,  which  is  likewise  evolyed  when  the  charcoal  is 
ignited  alone  (Bunsen,  Fopg.  46,  207)*.  When  a  large  quantity  of  va- 
pour of  water  acts  upon  a  small  quantity  of  charcoal,  the  hydrogen  gas 
produced  is  accompanied  chiefly  by  carbonic  acid  gas,  with  but  a  snudl 
quantity  of  carbonic  oxide.  (Gm.)t — All  metallic  oxides  which  give  up 
their  oxygen  to  charcoal  at  a  strong  red  heat,  as  oxide  of  zinc,  black 
oxide  of  iron,  and  protoxide  of  manganese,  convert  the  carbon,  either 
into  carbonic  oxide,  or  a  mixture  of  that  gas  with  carbonic  acid. — The 
gas  evolved  from  iron  furnaces  contains  from  25  to  32,  that  from  copper- 
refining  furnaces  13  to  19  per  cent  of  carbonic  oxide.  (Bunsen,  Pogg.  46, 
193;  50,81.) 

2.  Carbonic  oxide  is  likewise  formed  when  carbonic  acid,  either  free 
or  combined  with  an  alkali,  comes  in  contact  with  charcoal  or  iron  at  a 
red  heat,  and  gives  up  to  these  substances  its  second  atom  of  oxygen, 
which  is  less  intimately  combined  than  the  first.     {Scheme  1^,) 

3.  In  the  dry  distillation  of  many  organic  compounds. 

4.  In  the  decomposition  of  oxalic  or  formic  acid  by  oil  of  vitriol. 

5.  In  the  decomposition  of  ferrocyanide  of  potassium  by  oil  of 
vitriol. 

Preparation.  1.  In  a  gun-barrel  fitted  with  a  glass  tube  (App.  37), 
oxide  of  iron,  zinc,  lead,  or  copper,  is  heated  to  redness  with  ignited  char- 
coal or  plumbago ;  or  carbonate  of  potassa,  soda,  baryta,  strontia,  or  lime, 
with  ignited  charcoal,  plumbago,  or  iron  filings  ;•— or  carbonic  acid  gas 
is  passed  repeatedly  over  iron  filings  or  previously  ignited  charcoal  kept 
at  a  red  heat  in  a  ^un-barrol. — ^The  carbonic  acid  largely  mixed  with  the 
gas  thus  obtained  is  removed  by  agitation  with  milk  of  lime  or  solution 
of  pota^ssa. 

2.  Oxalic  acid,  or  an  oxalate  or  formiate  is  heated  with  oil  of  vitriol, 
and  the  carbonic  acid  removed  as  above. — Dobereiner  heats  oxalic  acid 
with  oil  of  vitriol,  and  removes  the  carbonic  acid  by  lime  or  potassa. — 
Dumas  {Ann.  Ckim,  Phys.  33,  110)  heats  binoxahkte  of  potassa  with 
6  parts  of  oil  of  vitriol,  and  passes  the  mixture  through  aqueous  solution 

*  Bansen  saye,  that  an  opinion  haa  hitherto  been  tmivenally  entertained,  and  has 
also  found  its  way  into  treatises  on  chemistry,  that  marsh-gas  is  produced  in  the  action 
of  aqueous  vapour  on  ignited  charcoal.  Nevertheless,  the  reaction  was  correctly  given 
by  Clement  &  Desormes  41  yean  ago.  In  the  2nd  and  3rd  editions  of  Omel%n*» 
ffandbueh,  also,  nothing  is  said  of  the  production  of  marsh-gas  in  this  manner. 

t  We  often  meet  with  the  erroneous  assertion  that  the  heat  which  may  be  obtained 
by  the  combustion  of  charcoal  is  increased  by  the  addition  of  water.  Those  who  make 
this  assertion  forget  that  when  the  oxygen  entered  into  combination  with  the  hydrogen 
to  form  water,  a  certain  quantity  of  heat  was  developed  which  must  be  deducted,  now 
that  the  water  is  decomposed  by  the  carbon.  The  quantity  of  heat  evolved  is  the  same, 
whether  carbonic  acid  is  formed  irom  the  combination  of  carbon  and  oxygen,  or  carbonic 
add  and  water  from  carbon,  oxygen,  and  water, — excepting  that  in  the  latter  case  an 
additional  quantity  of  heat  is  rendered  btent  in  the  formation  of  vapour  of  water.  The 
access  of  water  lessens  the  gloW'fire,  but  produces  a  greater  quantity  of  flame,  in  conse- 
quence of  the  formation  of  carbonic  oxide  and  hydrogen  gases. 


CARBONIC  ACID.  89 

of  potassa. — ^Mitchell  {SiU,  Am,  J.  25.  344)  heats  crystallized  oxalate 
of  ammonia  "with  from  -J^  to  ^  of  its  weight  of  oil  of  vitriol :  by  this 
means,  pare  carbonic  oxide  free  from  carbonic  acid,  is  evolved  from  the 
beginning  to  the  end  of  the  process.  According  to  Gale  (FhU.  Mag,  J. 
6,  232),  on  the  contrary,  this  method  yields  carbonic  oxide  gas  mixed 
with  an  equal  volnme  of  carbonic  acid. 

IT  3.  Finely-powdered  yellow  ferrocyanide  of  potassium,  heated  with 
eight  or  ten  times  its  weight  of  oil  of  vitriol,  yields  carbonic  oxide  in  a 
state  of  perfect  purity. — One  atom  of  crystallized  ferrocyanide  of  po- 
tassium and  6  atoms  of  oil  of  vitriol  produce  6  atoms  of  carbonic  oxide, 
2  atoms  of  sulphate  of  potassa,  3  atoms  of  sulphate  of  ammonia,  and  one 
atom  of  protosulphate  of  iron  (Fownes).  IT 

Properties,  Colourless  gas.  [For  its  refracting  power  and  specific 
gravity,  vid,  pp.  95  and  279,  Vol.  L] — It  is  inflammable;  does  not  sup- 
port the  combustion  of  other  bodies ;  has  no  taste,  but  a  faint  peculiar 
odour;  small  animals  immersed  in  it  die  instantly.  When  inspired,  it 
produces  giddiness  and  fainting  fits  (Clement  &  ^esormes),  even  when 
mixed  with  a  fourth  of  its  bulk  of  air  (H.  Davy);  it  is  much  more  poi- 
sonous than  carbonic  acid. 


0  

o 

6  

8  

42-86 

57-14 

Vapour  of  carbon  ?  .... 
OzTsen  na 

Vol.    Sp.gr. 
....    10    0-4160 
....    0*5    0-5546 

^••JO"—  o     

CO  

14  

100.00 

Carbonic  oxide  gas ... 

....    1-0    0-9706 

(CO  =  76-44  + 100  =:  176*44.    BeneUus.) 

DecomposiUons.  Heated  potassium  or  sodium  decomposes  this  gas, 
the  former  tiding  fire  in  it — ^the  products  being  oxide  of  potassium  or 
sodium  and  charcoal  (Gay-Lussac  &  Th6nard  Jiechet*ck^8,  1,  266). — 
Under  certain  circumstances,  potassium  seems  to  absorb  carbonic  oxide 
gas  without  decomposing  it  {vCd,  Croconic  acid), — Carbonic  oxide  is  like- 
wise decomposed  by  the  passage  of  electric  sparks  through  it,  or  by 
being  passed  through  a  red-hot  tube. 

CamlnfuUians.  Water  absorbs  -^  of  its  volume  of  this  gas,  accord- 
ing to  Davy  ;  -j^,  according  to  Dalton  ;  and  -^  according  to  Saussure. 

Carbonic  oxide  gas  likewise  combines  with  chlorine. 

B.    Carbonic  Acid.    CO*. 

Acid  of  air,  Luftrsaure  (Bergman),  Acid  of  chalk,  Kretdesdure  (Keir), 
Acide  carhoniqtie,  Acide  nUphitique  (G.  Morveau)  Kohlemdure ;  in 
the  gaseous  state  :   Carbonic  acid  gas,  Fixed  air  (Black),  Mepkitic 
air,  kohlensaures  Gas,  Gas  adde  carbonique,  Gas  carbonicum,  Gas 
sylvesire,  SpirUtu  sylvestris. 
Sources.     Carbonic  acid  issues  in  the  form  of  gas  from  the  ground  in 
various  localities  (Grotta  del  Cane,  Pyrmont,  Brohl ;  in  the  last  men- 
tioned place,   according  to  G.  Bischof  (Schw,  5e,   129),  the  quantity 
discharged  in  24  hours  amounts  to  600  lbs.).     Carbonic  acid  is  present  in 
the  air  in  the  ratio  of  0*0005  of  its  volume ;  more  abundantly  in  cellars 
and  mines   (Clioke-damp),— in  all  waters,  but  principally  in  acid  and 
chalybeate  waters ;  in  combination  with  ammonia,  potassa,  soda,  baryta, 
strontia,  lime,  magnesia,  protoxide  of  manganese,  oxide  of  zinc,  and  the 
protoxides  of  lead,  iron,  and  copper;  finally,  in  certain  organic  liquids. 


90  CARBON. 

FormcUion.  1.  la  tbe  combustion  of  carboDaceous  substancea  in  air 
or  in  oxygen  ga« : — a.  Diamond  takes  firo  in  oxysen  gas  at  a  strong 
red  heat  (more  easily  tban  graphite,  according  to  Dumas  &  Stas)  and 
burns  with  a  brilliant  red  light,  and  great  development  of  heat,  sufficient, 
according  to  Sir  H.  Dary,  to  fuse  platinum :  it  is  almost  wholly  consumed, 
even  when  the  supply  of  heat  from  without  is  cut  off:  the  unbnmt 
residue  is  white  and  opaque.  According  to  Ouyton-Morveau,  black- 
ening takes  place  at  an  earlier  stage  of  the  combustion. — 6.  Plumbago 
likewise  requires  a  very  high  temperature,  bums  very  slowly,  and  Uko 
diamond,  ceases  to  bum  in  the  open  air  as  soon  as  the  supply  of  heat 
from  without  is  interrupted. — c.  Organic  substances,  especially  charcoal, 
require  but  a  dull  red  heat  to  cause  them  to  enter  into  combustion ;  and 
the  process  once  begun  generally  proceeds  spontaneously  in  the  air. 
The  combustion  of  charcoiu  in  oxygen  gas  is  brilliant  and  attended  with 
rapid  emission  of  sparks.  In  many  chemical  processes  which  take 
place  in  or^nic  bodies,  carbon  combines  either  witn  oxygen  contained  in 
the  body  itself,  or  with  that  of  the  air,  the  combination  taking  place, 
sometimes  at  ordinary,  sometimes  at  slightly  elevated  temperatures,  and  the 
product  being  carbonic  acid:  e,  g,  in  Fermentation,  Putrefaction,  ana 
Kespiration.  In  the  combustion  of  diamond  and  pure  graphite,  the 
volume  of  the  gas  remains  unaltered,  the  oxygen  consumed  being  replaced 
by  an  equal  volume  of  carbonic  acid  gas.  Charcoal  bums  with  a  slight 
diminution  of  the  volume  of  gas,  in  proportion  to  the  hydrogen  which  it 
contains;  but  when  the  proper  deduction  is  made  for  the  water  produced, 
the  quantity  of  carbonic  acid  generated  is  found  to  be  not  less  than  that 
produced  by  the  combustion  of  diamond.  According  to  Von  Wrede's 
experiment  ^L,  258,  at  top),  the  volume  of  carbonic  acid  gas  produced 
under  the  ordinary  atmospheric  pressure  must  be  somewhat  less  than  that 
of  the  oxygen  consumed ;  but  under  a  pressure  of  half  an  atmosphere,  the 
volumes  of  the  two  gases  must  be  exactly  equal. 

2.  When  carbonaceous  bodies  are  brought  in  contact,  either  at  ordinary 
or  at  higher  temperatures,  with  many  of  the  less  intimate  compounds  of 
oxygen. — Thus,  carbonic  acid  is  formed  when  charcoal  is  boiled  in  sul- 
phuric acid,  nitric  acid,  &c.,  or  when  charcoal,  diamond,  or  graphite  is 
Ignited  with  vapour  of  water,  with  nitrates,  chlorates,  or  iodates,  or  with 
red  oxide  of  mercury,  black  oxide  of  manganese,  and  various  other  inetallic 
oxides. 

3.  In  the  combustion  of  carbonic  oxide.  Two  volumes  of  carbonic 
oxide  gas  combine  with  one  volume  of  oxygen  to  Ibrm  2  volumes  of  car- 
bonic acid  gas.  (Gay-Lussac.)  The  combination  is  induced  by  a  red 
heat,  by  the  electric  spark,  platinum,  &c.,  and  is  sometimes  slow,  some- 
times rapid.  When  the  two  eases  are  mixed,  it  is  accompanied  by  a 
slight  detonation,  and  the  production  of  a  bluish  flame :  when  the  com- 
bustion takes  place  gradually,  the  gas  exhibits  a  pale  blue,  lambent 
flame,  but  if  previously  heated  to  redness,  a  yellow  flame. 

Carbonic  oxide  gas  is  inflamed  even  by  the  heat  of  a  red-hot  ooal,  or 
red-hot  iron.  (H.  Davy.)  The  carbonic  oxide  must  amount  to  at  least  •^, 
and  the  oxygen  to  at  least  -^^  of  the  whole,  to  enable  the  mixture  to  take 
fire  by  the  electric  spark.  A  mixture  of  carbonic  oxide  and  air  continues 
to  burn  on  the  surface  of  a  heated  spiral  of  platinnm  wire.  (H.  Davy.) 
Ordinary  platinum  foil  does  not  act  on  a  mixture  of  carbonic  oxide  and 
oxygen  below  dOO"*.  (Dulong  &  Th^nard.)— Platinum  foil  prepared 
according  to  Faraday's  method  (p.  47),  condenses,  in  three  days,  half  a 
cubic  inon  of  a  mixture  of  2  cubic  inches  of  carbonic  oxide  and  I  cubif 


CARBONIC  ACID.  91 

inoh  of  oxygen.  The  oarbonic  acid  gas  produced  retards  the  action; 
consequently,  the  condensation  takes  place  more  quickly  when  the  gajseous 
mixture  is  placed  over  solution  of  potassa,  whicn  takes  up  the  carbonic 
acid  as  fast  as  it  is  formed.  (W.  Ch.  Henry.)  Spongy  platinum  intro- 
duced into  a  mixture  of  2  volumes  of  carbonic  oxide  and  1  volume  of 
oxygen  gas  induces  slow  combustion ;  but,  according  to  Dobereiner  and 
W.  Henry,  not  till  the  temperature  is  raised ;  according  to  the  latter, 
at  150'' :  according  to  Dulong  &  Thenard,  and  W.  Ch.  Henry,  on  the  con- 
trary, it  acts  at  ordinary  temperatures.  According  to  the  latter,  the 
spongy  metal  acts  more  quickly  than  the  prepared  foil,  and  with  par- 
ticular rapidity  when  potassa  is  present,  in  which  case  |  of  the  gaseous 
mixture  are  condensed  in  two  hours.  Platinum-paper-ash  (p.  50)  acts  at 
ordinary  temperatures  :  to  make  it  red-hot  in  the  gaseous  mixture  it  must 
be  heated  to  30^  according  to  Pleischl,  and  to  80°  according  to  De  la  Hive 
&  Marcet.  Liebig's  platinum-black  instantly  becomes  red-hot  in  a  mix* 
ture  of  carbonic  oxide  and  oxygen,  and  sets  fire  to  the  mixture :  even  in 
pure  carbonic  oxide  gas  it  becomes  red-hot,  and  produces  carbonic  acid, 
oecause  it  already  contains  oxygen  absorbed  within  its  pores.  (W.  Henry, 
W.  Ch.  Henry.)  Palladium-paper-ash  acts  upon  the  gaseous  mixture  at 
ordinary  temperatures,  and  becomes  red-hot  when  heated  to  120^ 
(Pleischl,  De  la  Rive  &  Marcet.)  Carbonic  oxide  is  also  ignited  by 
iridium-black,  but  not  by  spongy  iridium.  ( Dobereiner.)  Gold-leaf  does 
not  act  below  300^.  (Dulong  &  Thenard.)  If  spongy  platinum  be  allowed 
to  act  at  171°  on  a  mixture  of  2  measures  of  hydrogen,  2  of  carbonic  oxide^ 
and  1  of  oxygen,  till  condensation  no  longer  takes  place,  it  is  found  that 
the  Quantity  of  oxygen  which  has  combined  with  the  hydrogen  is  to  that 
which  has  combined  with  the  carbonic  oxide  and  formed  carbonic  acid^  as 
1  :  4  :  if  such  a  mixture  is  heated  in  a  glass  tube  without  spongy  platinum 
till  the  glass  softens,  slow  combustion  takes  place,  and  the  ratio  is  as 
3:2;  thirdly,  when  such  a  mixture  is  inflamed  by  the  electric  spark,  the 
ratio  of  the  quantities  of  oxygen  which  combine  with  the  hydrogen  and 
with  the  carbonic  oxide,  is  as  3  :  1.  Hence  it  appears  that,  at  higher  tem- 
peratures, the  oxygen  combines  by  preference  with  the  hydrogen  j  at  lower 
temperatures,  with  the  carbonic  oxide.     (W.  Henry.) 

Preparation,  1.  In  the  liquid  state :  a.  On  the  small  scale,  according 
to  Faraday's  method  (I.,  286).  The  oil  of  vitriol  must  be  made  to  act 
very  slowly  on  the  carbonate  of  ammonia;  otherwise  the  tube  will  burst, 
in  consequence  of  the  great  heat  evolved.  (Niemann.) — 5.  On  the  large 
scale.  In  a  cast-iron  cylinder,  49  centimetres  long,  and  27  wide,  con- 
taining about  6  litres,  having  walls  5  centimetres  thick,  strengthened  by 
6  ribs,  and  provided  in  the  middle  with  pins  on  which  it  rests  in  an 
upright  position,  and  can  be  moved  to  and  fro  for  the  purpose  of  mixing 
the  contents,---carbonic  acid  is  evolved  from  1800  grammes  of  bicarbonate 
of  soda,  4  litres  of  water  at  35°,  and  1000  grammes  of  oil  of  vitriol*. 
When  the  decomposition  is  quite  complete,  the  carbonic  acid  is  made  to 
pass  through  a  tube  furnished  with  a  stop-cock,  into  a  similar  cylinder 
placed  horizontally,  in  which  the  greater  part  of  the  acid  collects  and  con- 
denses, the  first  cylinder  becoming  heated  by  the  action  of  the  acid  on  the 
water  and  the  carbonate  of  soda.  After  a  minute,  the  cocks  are  closed, 
the  cylinders  separated,  and  the  charge  in  the  first  renewed ;  and  this 
process  is  repeated  a  third  time,  so  that  the  horizontal  cylinder  receives 

*  2ilbt.  of  bicarbonate  of  coda,  6ilb8.  of  water,  and  IJlb.  of  oil  of  vitriol. 


92  CARBON. 

at  least  three  charges,  and  becomes  filled  for  the  greater  part  with  liqaid 
carbonic  acid.  After  seven  charges^  the  quantity  of  carbonic  a^id  obtained 
amounts  to  4  litres.  (Thilorier,  Ann.  PAarm,  30,  122.)  0.  Hervey  was 
killed  by  the  bursting  of  the  first  cylinder,  while  swinging  it  to  and  fro 
for  the  purpose  of  mixing  the  second  charge.  (J,  Chim.  Med.  17,  61.) 
Mitchel  proceeds  in  the  same  manner  as  Thilorier.  Brunei  (</.  Pharm, 
12,  301)  recommends  compression  of  the  gas  by  means  of  a  pump. 

2.  In  the  solid  state.  From  the  second  cylinder  of  Thilorier's  apparatus, 
the  carbonic  acid  is  made  to  pass  through  a  tube  into  a  perforated  cylin- 
drical brass  box  divided  into  two  equal  parts  by  a  partition.  If  the  stop- 
cock be  closed  after  the  lapse  of  five  seconds,  a  snow-like  mass  of  solid 
carbonic  acid  about  as  large  as  a  duck's  egg  is  found  in  the  box.  (Thilo- 
rier.) When  an  ounce  of  liquid  carbonic  acid  is  sufiered  to  escape  in  the 
gaseous  form  by  opening  the  vessel,  a  dram  of  solid  carbonic  acid  remains 
behind,  having  the  appearance  of  magnesia  alba.     (Mitchell.) 

3.  In  the  gaseous  state.  Gold  dilute  sulphuric  or  hydrochloric  acid  is 
poured  upon  chalk  contained  in  a  gas- generating  vessel  {App.  41).  The 
acid  combines  with  the  lime,  and  sets  the  carbonic  acid  free.  (Scfteme  12.) 
To  free  the  gas  from  liquid  mechanically  carried  over,  it  may  be  passed 
through  water  contained  in  the  vessel  b  (App,  43).  Mohr  (Ann.  Pharm. 
29,  268)  places  pieces  of  chalk  on  a  plate  of  glass  or  copper  c  {App.  44), 
suspended  by  a  wire  in  the  lower  part  of  a  glass  bottle  6,  the  bottom  of 
which  has  been  removed — ^immerses  this  bottle  in  a  vessel  filled  with  dilute 
hydrochloric  acid— and  fits  the  upper  opening  of  the  bottle  with  stopper, 
cock,  and  gas -delivery  tube  e.  As  often  as  gas  is  let  out  at  the  top,  acid 
enters  the  bottle,  and  coming  in  contact  with  the  pieces  of  chalk,  evolves 
fresh  gas.  The  gas  is  received  over  water  or  mercury.  In  cases  in  which 
the  presence  of  nitrogen  is  not  hurtful,  carbonic  acid  gas  may  be  prepared 
by  passing  a  stream  of  air  over  red-hot  charcoal. 

Properties.  Solid  carbonic  acid  presents  the  appearance  of  a  white, 
floculent  mass  resembling  snow,  and  compressible  liko  that  substance.  A 
spirit  thermometer  immersed  in  it  sinks  to  — 87°  ( — 124*6'^  F)  ;  if  the 
whole  column  of  alcohol  were  immersed  in  the  mass,  the  temperature  indi- 
cated would  be  — 93°  ( — 135*4°  F).  When  exposed  to  the  air,  the  acid 
disappears  in  a  few  minutes,  and  often  leaves  behind  it  a  small  quantity 
of  water  condensed  from  the  air  by  the  cold.  Touched  with  the  finger 
when  resting  on  a  smooth  surface,  it  glides  quickly  forward,  as  if  sup- 
ported by  a  stratum  of  gas.  The  freezing  point  of  carbonic  acid  is  situated 
at  — Q5^  ( — 85°  F).  A  piece  of  solid  carbonic  acid  pressed  upon  the  skin 
of  an  animal,  stops  the  circulation  at  the  point  of  contact  by  the  depres- 
sion of  temperature  which  it  produces,  forms  a  white  spot,  and  after 
fifteen  seconds  a  blister :  if  the  carbonic  acid  be  then  removed,  a  white 
depression  with  raised  edges  is  produced ;  then  suppuration  takes  place, 
and  finally,  the  wound  heals  and  leaves  a  scar.  Hence  it  appears  that 
cold  produces  efiects  similar  to  those  of  heat,  attended,  however,  with  less 
pain.     (Mitchell,  Ann.  Pharm.  37,  354.) 

Liquid  carbonic  acid  is  transparent  and  colourless,  and  has  a  refracting 
power  much  smaller  than  that  of  water.  (H.  Davy  &  Faraday.)  Accord- 
ing to  Niemann  {Br.  Arch.  36,  190),  it  is  extremely  mobile,  and  refracts 
light  almost  as  strongly  as  water.  Its  specific  gravity  at  — 20®  is  0*90  ; 
at  0°,  0-83  ;  at  -|-  30°,  0*60°.     (Thilorier.) 

[^For  the  expansion  of  liquid  carbonic  acid  by  heat,  see  I.,  22.5  j  vapor- 
ization of  carbonic  acid  and  cold  produced  thereby,  I.,  259,  271,  273, 


CARBONIC  ACID.  93 

and  275 ;  elasticity  of  the  vapour  at  the  state  of  maximum  tension,  I., 
261.]  Carbonic  acid  gas  standing  oyer  liquid  carbonic  acid  in  a  close 
vessel  contains  at  0°,  -^^  of  its  volume,  and  at  30°,  |  of  its  volume  of 
liquid  carbonic  acid,  the  volume  of  the  latter  being  estimated  at  0°. 
(Thilorier.)  Liquid  carbonic  acid  obtained  by  the  action  of  sulphuric  acid 
upon  carbonate  of  ammonia,  exhibits  a  higher  tension,  in  proportion  as 
the  sulphuric  acid  is  less  diluted  with  water;  probably  because  the 
admixture  of  water  with  the  carbonic  acid  raises  its  boiling  point.  Thus, 
at  ]  2*5°,  the  tension  of  the  carbonic  acid  amounts  to  58  atmospheres,  when 
it  has  been  prepared  with  sulphuric  acid  of  specific  gravity  1*840;  to  50 
atmospheres,  with  acid  of  1  7 ;  to  49,  with  acid  of  1  '5 ;  to  46  with  acid  of 
1'3;  and  to  44  atmospheres,  with  acid  of  I'l  specific  gravity.  (Niemann, 
Ann.  Fharm.  1,  35.) 

At  ordinary  pressures,  carbonic  acid  is  a  colourless  gas.  (For  its 
refracting  power  and  specific  gravity,  see  I.,  95  and  279.)  It  is  incom- 
bustible, and  does  not  support  the  combustion  of  most  other  bodies.  The 
slight  reddening  which  it  imparts  to  tincture  of  litmus  disappears  on 
exposure  to  the  air,  in  consequence  of  the  evaporation  of  the  acid.  It 
produces  turbidity  in  baryta,  strontia,  and  lime-water,  when  passed 
through  them.  It  has  a  slightly  irritating  odour ;  and  when  inhaled,  either 
pure  or  mixed  with  a  tolerable  quantity  of  air,  it  produces  asphyxia  and 
death. 

Dumas  lAvoisier.  Clem.  &    Th.  Saussure.  Temiant.  Allen 

Calculation.       &  Stas.  Desormes.  &  Pepys. 

C     6     27-27       27-27  24  ....  28  27  ....  29     27*04  ....27*38      28        286 

20  16    72  73      7273  76 ....  72  73  ....  71     72*96  ...72*62      72        71*4 

CO«  22  100*00     100-00     100  ..100     100  ..  100      100  ..    100       100       100*0 

Vol.      Sp.  Gr.         or  Vol.        Sp.  Gp. 

Carbon  vapour?  1         0*4160        Carbonic  oxide  gas 1*0        0-9706 

Oxygen  gas 1         1*1092         Oxygen  gas 0*5         0*5546 

Carbonic  add  gas    1         1*5252        Carbonic  add  gas   1*0         1*5252 

(C0«  =  76*44  +  2  .  100  =  276*44.     BcrseUus.) 

Decompositions,  fiy  the  continued  passage  of  electric  sparks,  carbonic 
acid  gas  is  resolved  into  carbonic  oxide  and  free  oxygen.  (W.  Henry, 
Dalton.)  The  quantity  of  the  gas  thus  decomposed  must  always  be 
small,  since  the  electric  spark  causes  the  oxygen  and  carbonic  oxide  to 
recombine.  The  liquid  acid  is  not  decomposed  in  the  voltaic  circuit. 
(Niemann.) 

2.  Into  carbonic  oxide  and  combined  oxygen,  by  the  passage  of  elec- 
tric sparks,  when  hydrogen  gas,  mercury,  or  other  metals  are  likewise 
present  (Saussure,  Gilh.  13,  129  and  134);  also  when  heated  to  redness 
in  contact  with  hydrogen  gas,  charcoal,  iron,  or  zinc  (p.  89). 

3.  The  whole  of  the  oxygen  is  withdrawn,  and  carbon  separated  by 
heated  potassium  or  sodium  \Sch.  21),  the  former  becoming  red  hot,  and 
both  being  converted  into  alkaline  carbonates.  (H.  Davy,  Gay-Lussao  <fe 
Thenard.)  A  similar  effect  is  produced  by  phosphorus  (^ch.2Q'y  Smithson 
Tennant,  Crell.  Ann.  1793, 1,  158),  and  by  boron  (Gay-Lussac  &  Thenard), 
when  these  substances  come  in  contact  at  a  red  heat  with  carbonic  acid  in 
combination  with  a  fixed  alkali  (see  I.,  124).  Liquid  carbonic  acid  is 
decomposed  by  potassium  with  effervescence,  even  in  the  cold,  but  not  by 
zinc,  lead,  iron,  or  copper  (Thilorier) ;  phosphorus  does  not  decompose  it, 
even  when  heated.     (Niemann.) 


94  CARBON. 

Camhinationi,  a.  With  water. — The  liquid  acid  doe«  tiot  mix  with' 
water^  but  floats  on  the  top  after  being  shaken  np  with  it.  (Thilorier, 
Mitchell.)  Aqtteous  carbonic  acid.  Water,  at  ordinary  temperatures, 
absorbs  its  own  rolume  of  carbonic  acid  gas,  and  thereby  requires  a  specific 
gravity  of  I'OOIS;  at  increased  pressure  and  lower  temperatures  it  takes 
twice  or  three  times  as  much,  estimatiuj?  the  quantitj^  by  weight:  Add 
Water,  SauerwoMer. — Water  impregnated  with  carbonic  acid  has  a  sharp 
and  slightly  acid  taste.  Heat,  the  action  of  the  air-pump,  exposure  to  the 
air,  or  congelation,  causes  the  carbonic  acid  to  escape  (compare  page  68). 

6.  Carbonic  acid  unites  with  most  salifiable  bases,  forming  salts  allied 
Carbonates,  In  its  affinity  for  bases,  it  is  one  of  the  weakest  of  all  acids; 
and  in  consequence  of  the  feebleness  of  its  acid  properties,  it  does  not  mask 
the  alkalinity  of  ammonia,  potassa,  and  soda,  when  united  with  them  in 
simple  atomic  proportions  (page  7).  From  the  same  cause,  it  may  bo 
separated  by  heat  from  all  bases  exceptingammonia,  potassa,  soda,  and  lithia. 
The  carbonates  are  likewise  decomposed  by  most  other  acids,  the  carbonic 
acid  escaping  as  gas  with  its  own  peculiar  odour.  All  basic  and  normal 
carbonates  are  insoluble  in  water,  excepting  those  of  ammonia,  potassa, 
soda,  and  lithia ;  but  all  acid  carbonates  are  soluble  in  water,  to  a  certain 
extent,  indeed,  existing  only  through  its  agency.  The  soluble  carbonates, 
as  well  as  free  carbonic  acid,  may  therefore  be  detected  in  solution  by  the 
white  precipitate  soluble  in  hydrochloric  acid,  which  they  give  with 
lime,  strontia^  or  baryta- water.  Baryta- water  is  rendered  slightly  turbid 
by  a  solution  of  carbonate  of  soda  containing  1  part  of  carbonic  acid  in 
between  40,000  and  80,000  parts  of  water ;  to  produce  a  sensible  precipi- 
tate in  lime-water,  the  proportion  of  water  must  not  exceed  20,000  parts 
to  1  part  of  carbonic  acid.     (Lassonne.    J.  Chim,  Med.  8,  523.) 

IT  The  following  table  of  the  solubility  of  certain  earthy  and  metal- 
lic carbonates  in  water  saturated  with  carbonic  acid  is  given  by  Lassaigue 
{J.  Chim.  Med.  1848,  June,  p.  312.)  IT 

In  Equiyaleots. 
Carbonate  of  lime  at    0**  in  1428  pts.  water  6CO«:  ICaO 

—    at  10**  in  1136      „ 

baryta  at  10»  in    588      6CO«:  IBaO 

-  strontia at  10'' in     833       6CO«:  ISrO 

manganese.,  at  —  in  2000      3C0«:  MnO 

aUrer     at  10°  in    961 

zinc  1428 

copper  3333 

lead  7144 

€.  Carbonic  acid  gas  is  absorbed  by  alcohol  and  other  oiganic  liqoidB.* 

Other  Compounds  of  Carbon, 

A.  With  Phosphorus.— B.  With  Sulphur.— C.  With  many  metals^ 
especially  Iron,  forming  Metallic  Carbides  or  Carburets. — D.  In  aU  organic 
compounds. 

*  The  omnpoandi  of  carbon  and  hydrof  en  will  be  deacribed  amoag  orgudc  ooB|K>iaid8. 


BORON.  9i 

Chapter  IV. 

BORON. 


Homberg.     Boracie  Acid.  CrelL  Chem.  Archiv,  2,  265. 
Geoffrey.      Boracie  Acid.  CreU.  n,  Chem.  Archiv.  3,  217. 
Gaj-LtiBsac  &  Th^nard.  Decomposition  of  Boracio  Acid.     Reeher^et, 

1,276;  alsoGilb.  30,  363. 
Sir  H.  Dary.     Decomposition  of  Boracie  Acid.    Phil,  Trans.  1809, 

I.,  75;  Sckw.  2,  48;  Oilb.  35,  440. 
Berzelias.  Boracie  Acid.    Schw.  23,  160. — Boron  and  Boracie  Acid. 

Pogg.  2,113. — Boracie  Acid.  Fogg,  84,  560. 
L.  Gmelin.  Boracie  Acid.  Schw.  15,  245. 
Sonbeiran.  Boracie  Acid.  J.  Pliarm,  11,  29  and  558 ;  also  N,  Tr, 

11,  1,  191 ;  also  Mag,  Pharm,  11,  13. 
Tiinnermann.  Boracio  Acid.  Kattn,  Arch,  20,  1. 


Baracittmf  Bora,  Bor,  Bore, 

Hittory,  Homberg,  in  1702,  disooyered  boracio  acid  in  borax.  In 
1808,  this  acid  was  decomposed  by  Gay-Lnssac  &  Th^nard,  and  imme* 
diately  afterwards  by  Sit  H.  Davy,  into  oxygen  and  the  pperiously  un- 
known element.  Boron, 

Sources,  Boron,  together  with  iodine,  bromine,  and  selenium  is  among 
the  least  abundant  of  the  non-metallic  elements  :  it  occurs  exclusively  in 
the  form  of  boracie  acid. 

Preparation,  Vitrefied  boracie  acid  in  the"  state  of  powder,  mixed 
with  an  equal  weight  of  potaraium  cut  up  into  small  pieces,  is  heated  to 
redness  for  some  minutes  in  a  tube  of  iron,  copper,  platinum,  or  glass, 
connected  with  a  pneumatic  tube.  The  mass  is  then  well  boiled  with 
very  dilute  hydrochloric  acid,  washed  with  water,  and  dried  at  a  gentle 
heat.  (Gay-Lussac  &  Th^nard.)  Boracio  acid  being  seldom  perfectly 
anhydrous,  the  process  is  generally  attended  with  detonation  and  spirting. 
In  proportion  as  the  potasssrsalt  is  removed  by  washing,  the  boron  be- 
comes mixed  with  the  water  in  so  very  fine  a  state  of  division,  that  it 
runs  through  the  filter ;  and,  when  the  greater  part  of  the  salt  has  been 
removed,  even  dissolves  in  the  water  to  a  slight  extent,  imparting  a  yellow 
colour  to  it.  The  addition  of  acids  or  salts  to  the  water  prevents  the  fine 
division  and  solution  of  the  boron.  It  is  better,  therefore,  to  wash  with 
water  containing  sal-ammoniac,  and  then  remove  the  sal-ammoniac  by 
means  of  alcohol.  Boron  thus  obtained  is  tolerably  free  from  siiicium. 
(Berzelius.)  If  the  boracie  acid  be  deprived  a«  much  as  possible  of  water 
by  fusing  it  in  a  platinum  crucible,  and  then  coarsely  pounded — and  a 
double  quantity  of  potassium  be  used,  freed  from  the  crust  of  hydrate  of 
potassa,  &c,,  wnich  generally  adheres  to  it, — ^the  mixture,  when  gradually 
heated  in  a  fflass  tube  over  a  spirit-lamp,  and  kept  at  a  red  heat  for  ten 
minutes,  produces  no  explosion,  but  undergoes  tranquil  decomposition, — 
and  after  being  boiled  with  water  acidulated  with  hydrochloric  acid 
(whidi  causes  no  evolution  of  hydrogen  gas),  and  then  washed  on  a  filter 


96  BORON. 

with  pnre  water^  it  vieldB  boron.     (R.  D«  Thomaon,  PhU.  Mag.  J.  10, 
419.) 

2.  Gaseous  fluoride  of  boron  is  passed — first  through  a  tube  filled  with 
crystallized  boracic  acid — then  through  another  containing  peroxide  of 
lead,  to  free  it  from  fiuoride  of  silicium  and  sulphurous  acid — and  lastly 
over  heated  potassium,  which,  as  soon  as  the  black  crust  formed  at  the 
commencement  has  burst,  bums  with  a  red  fiame  and  produces  a  mixture 
of  boron  and  fluoride  of  potassium.  The  latter  is  remored  by  washing  with 
water,  which  however  is  attended  with  considerable  difficulty.  Boron 
thus  obtained  contains  0*4  of  silicium,  which  remains  behind  when  the 
boron  is  dissolved  in  nitric  acid ;  moreover,  the  solution  has  a  yellow 
colour,  proceeding  from  carbon  previously  mixed  with  the  potassium. 
(Berzelius.) 

3.  Fluoride  of  boron  and  potassium,  dried  by  a  heat  almost  amounting 
to  redness  and  then  pounded,  is  placed,  together  with  an  equal  Quantity 
of  potassium,  in  a  tube  of  iron  or  glajss  closed  at  the  bottom  (irom  the 
latter,  however,  a  portion  of  silicium  may  be  reduced).  Heat  la  then  ap- 
plied till  the  potassium  melts,  and  the  mass  is  worked  about  with  a  steel 
wire  till  a  uniform  mixture  is  obtained ;  it  is  then  heated  to  redness,  at 
which  temperature  the  fluorine  is  transferred,  without  detonation,  from 
the  boron  to  the  potassium.  The  mass  is  next  freed,  by  repeated  boiling 
in  water  containing  sal-ammoniac,  from  fluoride  of  potassium  and  from  the 
undecomposed  and  very  difficultly  soluble  fluoride  of  boron  and  potas- 
sium (the  greater  the  excess  of  potassium  used,  the  smaller  is  the  quantity 
of  this  latter  compound  which  remains :  in  the  decomposition  of  flnoridb 
of  boron  and  sodium  by  metallic  sodium,  no  such  difficultly  soluble  salt 
would  be  formed).  The  boron  is  then  ignited  in  an  atmosphere  of  hydro- 
^n,  whereby  it  evolves  water  and  hydrofluate  of  boracic  acid,  and  loses 
its  capability  of  diffusing  itself  through  water  and  dissolving  in  it. 
Finally,  it  is  washed  repeatedly  with  water  and  dried  in  vacuo.  Boron 
thus  obtained  is  tolerably  pure,  but  when  burned  in  oxygen,  produces 
small  quantities  of  water  and  carbonic  acid.  (Berzelius.) 

4.  Hydrated  chloride  of  boron  is  decomposed  at  a  red  heat  by  hydro- 
gen gas.     (Dumas,  Ann,  Chim.  Phys,  31,  376.) 

Dbbereiner's  method  {Schw.  16,  116)  of  preparing  carbonized  boron 
by  placing  a  mixture  of  109*5  parts  of  ignited  borax  with  11*4  of  lamp- 
black in  a  gun- barrel  and  heating  it  to  whiteness  for  two  hours, — ^then 
exhausting  the  fused  mass  with  boiling  water,  and  flnally  with  hydro- 
chloric acid— did  not  prove  successful,  either  in  Pleischl's  hands  or  in  the 
author's. 

Properties^-^jyATk  greenish  brown,  opaque,  friable,  not  capable  of 
scratching  fflass.  After  exposure  to  a  white  neat  out  of  contact  of  air,  it 
sinks  rapidly  in  oil  of  vitriol.  It  neither  melts  nor  sublimes  even  at  the 
strongest  white  heat ;  does  not  conduct  electricity.  Tasteless  and  inodor- 
ous. (Gay-Lussac  &  Th6nard.) 

Compounds  of  Boron, 

Boron  and   Water. 

Aqueous  Solution  of  Boron, — Freshly  prepared,  unignited  boron  dis- 
solves in  pure  water,  producing  a  greenisn-yellow  solution.  Acids  and 
salts  separate  the  boron  from  the  solntioiu     W  hen  the  liquid  is  evaporated 


BORACIC  ACID.  97 

in  a  glass  dish,  a  greenisb-jellow  film  is  produced  on  the  edge,  easily 
separable,  and  only  partially  soluble  in  fresh  water.  (Berzelius.) 

Boron  and  Oxygen. 

BoRACio  Acid.    BO'. 

SedoHve  Salt,  Narcotic  VitrioUSalty  Boron$aure,  Borsaure,  Acide 
haraciquey  Acide  boriquCy  Acidum  boracis,  Sal  sedativum  Hombergii,  Sal 
narcoticum  vitrioli. — Found  in  the  free  state  in  solution  in  the  Laguni  of 
Tuscany — small  hot  lakes,  into  which  vapours  rise  from  the  volcanic 
bottom  :  the  boracic  acid  crystallizes  on  the  edges  of  these  lakes  in  the 
form  of  SaBSolin,  It  also  occurs  in  combination  with  salifiable  bases  in 
Tincal,  Boracite,  Hydroboracite,  Datolite,  and  Botryolite,  and  in  small 
quantities  in  Schorl,  Apyrite,  Axinite,  and  Rhodizite. 

Formation. — Of  all  the  non-metallic  elements,  boron  and  carbon  have 
the  strongest  afiinity  for  oxygen.  Boron  does  not  oxidize  in  the  air  or  in 
oxygen  gas  at  ordinary  temperatures — ^but  oxidation  begins  at  about  300"*. 
It  then  bums  in  the  air  with  a  reddish  light,  but  in  oxygen  gas  with 
dazzling  brightness,  and  always  with  lively  emission  of  sparks  (according 
to  Berzelius,  a  green  fiame  is  likewise  observed).  Boracic  acid  sublimes, 
and  there  remains  a  black  substance*  covered  with  glassy  boracic  acid : 
this  substance,  by  alternate  washing  and  combustion  several  times  re- 
peated, may  likewise  be  converted  into  boracic  acid.  (Gay-Lussac  & 
Th^nard.) 

Boron  does  not  decompose  water  at  a  boiling  heat :  it  readily  decom- 
poses oil  of  vitriol  when  heated,  and  nitric  acid,  even  though  but  slightly 
concentrated,  in  the  cold — the  product  in  all  cases  being  boracic  acid. 
At  a  red  heat,  it  decomposes — sometimes  with  development  of  light  and 
heat,  and  in  the  case  of  nitre,  with  brisk  detonation-— carbonic,  sulphur- 
ous, sulphuric,  nitrous  and  nitric  acids  combined  with  alkalis,  an  alka- 
line borate  being  formed,  while  carbon,  sulphur  or  nitrogen  is  set  free.  It 
also  decomposes  many  of  the  heavy  metallic  oxides  at  a  red  heat ;  and  if 
the  oxide  is  in  excess,  the  part  of  it  which  remains  undecomposed  unites 
with  the  boracic  acid  produced  and  forms  a  borate.  (Guy-Lussac  &  Th6- 
nard.)  Hydrate  of  potassa  heated  with  boron  is  converted,  with  evolu- 
tion of  hycbogen  gas,  into  borate  of  potassa.  From  an  aqueous  solution 
of  chloriae  of  gold,  boron  precipitates  metallic  gold.  (Berzelius.) 

Preparation.  1.  The  water  of  the  Laguni,  evaporated  in  leaden 
pans  by  the  heat  of  the  vapours  which  issue  from  the  grounds,  yields 
the  Tuscan  Boracic  add,  as  it  is  prepared  on  the  lai^gp  scale  (Bowring, 
y.  Ed.  Phil.  J.  28,  85;  also  Ann.  Pkarm,  34,  350  ;— Payen,  u4n«.  Chim. 
Pkys.  76.  247;— Thomson  RepeH.  68,  382).— The  acid  thus  obtained 
contains  3. 18  per  cent,  of  ammonia.  (Erdmann,  J.  pr.  Chem.  13,  72.)  It 
contains  only  76.  494  per  cent,  of  crystallized  boracic  acid,  besides  8*5 
sulphate  of  ammonia,  and  smaller  quantities  of  free  sulphuric  acid,  the 
sulphates  of  potassa,  soda,  lime,  magnesia,  protoxide  of  manganese,  sesqui- 

*  This  substance  is  distinguished  from  ordinary  boron  by  its  black  colour,  and  by 
the  higher  temperature  which  it  requires  for  combustion.  Gay.Lussac  &  Th^nard 
do  not  decide  whether  it  contains  oxygen  or  not :  according  to  Davy,  it  is  a  suboxide 
of  boron,  containing  0*25  oxygen:  according  to  Berzelius,  it  is  boron,  merely  mechani- 
cally altered  by  elevation  of  temperature. 

VOL.  II.  H 


98  BORON. 

oxide  of  iron,  and  alumina; — also  sal-ammoniac  and  tilica.  (WttUUiii, 
Eepeit.  72,  145.) 

2.  A  solution  of  one  part  of  borax  in  4  parts  of  boiling  water  is 
mixed  with  one- third  the  quantity  of  oil  of  vitriol :  on  cooling,  the  boracic 
acid  crystallizes  out :  an  additional  quantity  may  be  obtained  by  further 
evaporating  and  cooling  the  liquid.  The  liquid,  may  also  be  evaporated 
to  dryness  and  the  boracic  acid  extracted  by  hot  alcohol.  (Meissner,  N,  Tr. 
1,  2,  460.)— -Wackenroder  {N,  Br.  Arch.  21,  313)  uses  hydrochiorio  acid 
in  preferenoe  to  sulpharic,  because  the  latter  adheres  more  obstinately  te 
the  separated  boracic  acid.  Formerly,  the  acid  was  prepared  by  tub* 
limatiou  :  e.  g.  by  heating  to  redness  in  a  retort  a  mixture  of  16  parts 
borax,  2  water,  and  5  oil  of  vitriol.  The  powdered  residue  was  repeoAedly 
moistened  with  water  and  again  ignited.  The  product  was  much  smaller 
than  that  obtained  by  the  process  above  described. 

To  purify  the  crystallized  acid  from  adhering  sulphate  of  soda,  it  is 
again  dissolved  in  hot  water  and  re-crystallized  :  afterwards,  it  is  fused 
in  a  Hessian  or  platinum  crucible  till  the  liquid  mass  becomes  tranquil — 
by  which  treatment  it  is  freed  from  water,  sulphuric  acid,  and  the  oily 
matter  which  adheres  to  the  borax — then  poured  out,  and  the  Viir^jUd 
Boracic  acic^  preserved  in  well  stopped  bottles.  According  to  EobiquH 
(Ann.  Chim.  PAys.  17,  216),  it  still,  when  in  this  state,  retains  0225  of 
water,  of  which  it  can  only  he  deprived  by  ignition  with  oxide  of  copper. 

Properties.  Boraeio  acid  forms  a  colourless,  transparent,  very  hard, 
very  coherent,  and  brittle  glass ;  specific  gravity,  at  4^  (d9-2'^F.)in  vacae 
=  1  -83.  (Royer  &  Dumas.) — It  fuses  at  a  red  heat,  but  is  perfectly  fixed  in 
the  fire  when  alone ;  whereas  when  united  with  water,  aqueous  aeids,  or 
aleohol,  it  partly  vaporizes  in  company  with  them.  Boracic  acid  fused 
in  a  platinum  crucible  cracks  spontaneously  on  cooling  and  exhibits, 
along  the  cracks,  a  vivid  light  visible  even  by  day.  (Dumas,  Ann.  Chim, 
Phys.  32,  335  ;  also  Pogg.  7,  535.)  It  is  perfectly  inodorous ;  destitute 
of  corrosive  power ;  has  a  slightly  bitter  but  not  sour  taste  (£.  Davy, 
iV.  JSd.  Phil.  J,  e,  131);  and  reddens  litmus  but  very  feebly.  Its  alco- 
holic solution  and  its  ndxture  witli  sulphur  {Taschenb,  IIBO,  86)  bom 
with  a  green  flame. 

Qtn-hmuc  & 
Calculation.  Benelins.  Dsvr.         Thra.  (approi.) 

B        10-8    ....  31'04  31-1896  33    ....    36  67 

30        24    68-96  68*8104  67    ....    64  33 

BO^        34*8  ....  10000  1000000  100    ...100  100 

(BO*  s:  136*2  <!- 3  .  100  «  436-2  .  BeneUu.) 
Berzelius  fonnerly  estimated  the  atomic  weight  of  boron  at  double  its 
present  value,  and  supposed  that  in  boracic  acid  6  atoms  of  oxygen  were 
united  with  one  of  boron.  The  atomic  weight  of  boracic  acid  wa«  thereby 
made  twice  as  great  as  it  is  reckoned  in  the  preceding  table,  according 
to  the  latter  hypothesis  of  Berzelius,  viz.  216  +  6.  8  =  69*6.  According 
to  the  new  hypothesis,  the  borates  contain  twice  as  many  atoms  of  acid 
as  they  were  supposed  to  contain  according  to  the  old.  Assuming  the 
truth  of  the  new  theory,  the  atomic  weight  of  boracic  acid  (that  of  hy- 
drogen =  1)  is,  according  to  the  experiments  of  Payen  (./.  Chim.  Med,  4. 
159)  =  3514  ;  of  Berzelius  =  348;  of  Soubeiran  =  32-8. 

Decompositions.      Potassium,  at  elevated  temperatures,  decomposes 
boracic  acid  with  evolution  of  light  and  heat ;  sodium  efieets  the  decern* 


BORACIC  ACID.  99 

pcftition  quietly.  (Oay-Ln«aac  &  Tfa^nard.) — Charcoal  does  not  decompie 
It  at  a  white  heat ;  neither  does  phosphorus  when  its  vapour  is  macfe  to 
pass  over  red-hot  borate  of  baryta.  (Gm.)  The  decomposition  which 
Sir  Humphry  Davy  thought  he  observed  in  the  voltaic  circuit,  appears, 
from  the  experiments  of  Faraday  and  Connell,  to  be  rather  doubtful. 

OomMnations, — a.  With  water. 

a.  HydrtUe  of  Boracic  ado?.— Obtained  by  heating  the  crystallized 
acid  considerably  above  100°  j  it  then  loses  half  its  water.     (Berzelins.) 

CalcnlAtion.  Berzelins. 

2B0»  69-6    72^05  71'88 

3HO    27       27-96  28.12 


3H0,  2B0>   96-6    10000    10000 

/9.  CrystMued  Boracic  acid.  This  compound  crystallizes  on  cooling 
from  a  hot  solution,  in  white  scaly  six-sided  laminas,  haviug  a  faint  pearly 
lustre,  flexible,  and  greasy  to  the  touch :  when  the  solution  is  contam* 
inated  with  sulphuric  acid  or  Cutty  matters,  the  crystals  acquire  a  much 
larger  size  than  when  they  separate  from  a  pure  solution.  Crystalline 
system,  the  doubly  oblique  prismatic  {Fig.  129).  y :  t;  =  80°  30',  y :  «  = 
84«  53',  y  :  2  =  7.5«  30',  t; :  m  ==  118^  30',  v:  «  =  120°  45',  «:  «  =  120« 
45'  (this  must  be  a  misprint  in  the  memoir);  perfectly  deavable  parallel 
to  y:  frequently,  macle-crystals,  in  which  the  axis  of  rotation  is  pa* 
rallel  to  the  line  of  intersection  of  u  and  v,  and  the  surface  of  junction  pa- 
rallel the  face  z,  (Miller,  Poyg,2S,  558.) — Sp.  gr.  =  1*479.  (Kirwan.) 

Calculation.  Davy.        Payen.        Ben.  Fleischl.       Thomson. 

BO»      34-8    ....  56-31 57 56-66 56 56  ....  55 55-5 

3HO        27       ....  43-69 43 43*34 44 44  ....  45 44*5 

3HO.BO»  61-8    ....100-00 100 10000 100 100  ....100 lOO'O 

The  crystals  retain  their  water  at  100°,  bnt  give  up  half  of  it,  without 
melting,  at  a  higher  temperature,  and  the  whole  of  it  with  great  frothing 
at  a  red  heat,  the  aqueous  vapour  carrying  with  it  a  portion  of  the  hy- 
drated  boracic  acid. 

y.  Aqueous  solution  of  Boracic  add.  One  part  of  the  crystallized 
acid  dissolves  in  25*66  parts  of  water  at  19°,  in  14*88  at  25°,  in  12-66  at 
57^  in  10-16  at  50^  in  612  at  62  5°,  in  4  73  at  75°,  in  3*55  at  87*5° 
and  in  2-97  parts  at  100°  (Brandes  &  Fimhaber,  Br.  Arch,  7,  50). — 
The  specific  gravity  of  a  solution  saturated  at  8°  is  1*014.  (Anthon.) 
When  the  solution  is  evaporated,  a  large  quantity  of  boracic  acid  is 
volatilized. 

h.  With  salifiable  bases,  boracic  acid  forms  a  class  of  salts  called 
Borates.  Its  affinity  for  bases  is  but  little  greater  than  that  of  carbonic 
acid ;  but  at  a  red  heat  it  expels  all  acids  which  are  more  volatile  than 
itself.  In  the  borates,  one  atom  of  base  is  united  with  |,  1,  1|,  1|,  2,  3, 
4,  or  6  atoms  of  acid.  Most  of  these  salts  may  be  melted  into  a  trans- 
parent glass,  which  dissolves  various  metallic  oxides  with  characteristic 
colours :  they  are  not  decomposed  at  a  red  heat  by  charcoal  or  phospho- 
rus. Most  acids  separate  the  boracic  acid  from  them;  consequently, 
when  they  are  heated  in  contact  with  sulphuric  acid  and  alcohol,  the 
alcohol  bams  with  a  green  flame.  If  a  red-hot  platinum  wire  be  dipped 
into  a  pounded  mixture  of  any  borate  with  an  equal  quantity  of  bisuU 
phate  of  potassa,  and  then  held  in  the  blowpipe  flame,  the  flame  will 

B  2 


loo  PHOSPHORUS. 

exUbit  a  green  tint  (Turner,  Erdmann,  Schtio.  59,  86.)  All  the 
borates,  with  the  exception  of  those  of  ammonia,  potaasa^  aoda,  and 
lithia,  are  difficultly  soluble  in  water. 

c.  Boracic  acid  dissolves  in  several  of  the  stronger  acids,  especiallj  in 
sulphuric  acid. 

d.  It  is  soluble  in  alcohol  and  oils. 

BoBON  AND  Hydrogen. 

BoruretUd  Hydrogen-gcut  Boron  heated  in  hydrogen  gas  does  not 
dissolve  in  it.  The  gas  evolved  by  the  action  of  boride  of  potassium 
upon  water  is  supposed  by  Davy  to  be  boruretted  hydrogen  ^as.  By 
heatinj?  to  whiteness  a  mixture  of  iron  filings  and  ^  of  vitrefied  boracio 
acid,  the  author  obtained  a  coherent  mass  which  he  supposed  to  contain 
a  small  quantity  of  boride  of  iron,  together  with  boracic  acid  and 
metallic  iron.  On  dissolvins;  this  substance  in  hot  hydrochloric  acid,  a 
eas  was  obtained  which  smelt  like  the  hvdrogen  gas  evolved  from  water 
by  the  action  of  cast  iron.  This  gas,  when  mixed  with  air,  burned  with 
strong  detonation  and  a  reddish-yellow  flame;  exhibited,  when  slowly 
burned,  a  yellow  flame  with  a  fi;reen  border;  formed  a  white  cloud  with 
nitrous  acid ;  but  did  not  absorb  a  greater  quantity  of  oxygen  than  pure 
hydrogen  absorbs.  The  author  attributed  these  peculiarities  to  the 
presence  of  a  small  quantity  of  boron ;  but  they  are  more  probably  due 
to  the  other  impurities  usually  present  in  hydrogen  gas  evolved  by  the 
aid  of  iron.     (  Vid.  p.  44.) 

Other  Compounds  of  Boron.  With  Sulphur,  Sulphuric  acid?  Chlo- 
rine, Hydrochloric  acid?  Flaorine,  and  Potassium. 


Chapter  V 

PHOSPHORUS. 


Phosphorus  in  General. 

Kunckel,  in  hiBLahoratortum  Chymicum,  Hamb.  andLeipx.  1716,  p.  660. 

Boyle.     Philosophical  Transactions.     No.  135,  196,  and  198. 

Homberg.     Mhn.  de  VAcad.  des  Sc.  1692.     p.  101. 

Marggraf,  in  seinen  Ohemiscfien  Schrifien.     Berl.  1762,  B.  1.  s.  42 

Crell.     Crell.  Chem.  J.  1,  23;  2,  137;  4,  88. 

Thenard.  Ann.  Chim.  81,  109;  also  Schw.  4,  212;  also  Oilb.  44, 
341.     Ann.  Chim.  85,  326;  also  (?i76.  46,  270. 

H.  Davy.  Phil.  Trans.  1809,  I,  67.  Schw.  1,  481;  also  Gilb.  35,  288. 
Schte.  1,  484;  also  GUb.  36,  184.  PhU.  Trans.  1812,  405;  also 
Schw.  7,  494;  also  Gilb.  46,  273.  Phil.  Trans.  1818,  316;  also 
Ann.  Phil.  13,  210 ;  also  Schiv.  30,  294;  also  N.  Tr.  3,  2,  405. 


PHOSPHORUS.  101 

Gay-Lassao  &  Th^nard.  Verification  of  tbe  Decomposition  Experiments 
of  Davy,  &c.  Recherckes,  1,  187;  also  Schw.  I,  488;  also  GW>. 
B5y  292. 

Phillips.     Behaviour  of  Phosphorus  in  Water.    Ann.  Phil.  21,  470. 

While  Phosphorus  and  Red  Phosphoric  Oxide. 

Bbckmann.     U^)€r  das   VerhcUten  des  Phosphors  in  mehreren  Oasarten. 

Erl.  1800.     Action  of  Light  upon  Phosphorus.    Scher.  J.  5,  243. 
A.  Yogel.     Action  of  Light  upon  Phosphorus.    Schw.  7,  95 ;  also  GUb. 

45,  63.     GUb.  48,  375. 
Pelouze.    J.  Chim.  Med.  8,  530;  also  /.  Pharm.  18,  417 ;  also  Schw.  es, 

444;  also  Ann.  Pharm.  8,  52. 
H.  Rose.     White  Phosphorus. 
Leverrier.     Ann.  Chim.  Phys.  65,  257;  also  Ann.  Pharm.  27, 167;  abo 

J.pr.  Chem.  14,  18. 

Hypophosphorous  and  Phosphorous  Add. 

Fourcroy  8c  Vauquelin.     Salts  of  Phosphorous  acid.     J.  Polytechn.  4, 

655. 
Thomson.     Phosphorous  acid.     Ann.  Phil.   15,  227;  also  N.  Tr.  5,  2, 

441. 
Dulong.     Hypophosphorous  and  Phosphorous  acids.     Ann.  Chim.  Phys, 

2,  141;  liiaoSchw.  18,164. 
H.  Rose.     Hypophosphorous  acid.     Pogg.  9,  225,  and  361 ;  12,  77|  and 

288.— Phosphorous  acid.     Pogg.  8,  205;  9,  23,  and  215. 
Wnrtz*     Acids  of  Phosphorus.    Ann.  Pharm.  58,  49. 

Phosphoric  Acid. 

Wiegler.     Phosphoric  acid  from  Bones.     CreU.  N.  Entd.  2,  5. 

Val.  Rose.     Composition  of  Phosphoric  acid.     N.  Gehl,  2,  309. 

Thomson.     Ann.  Phil.  7,  305;  also  Schw.  17,  222. 

Dalton.     Manchester,  Mem.  Sec.  Ser.  3;  ahstr.  Ann.  Phil.  15,  136. 

Berzelius.     Composition  of  Phosphoric  and  Phosphorous  acids  and  their 

salts.     GUb.  53,  393;  54,  31;  also  Ann.  Chim.  Phys.  2,  151.  217, 

and  329.     Further:  Ann.  Chim.  Phys.  10,  278. 
Mitscherlich.     Salts  of  Phosphoric  acid.     Ann.  Chim.  Phys.  19,  350. 
Gay-Lussac.     Modifications  of  Phosphoric  acid.     Ann  Chim.  Phys.   41, 

331;  also  N.  Tr.  20,  1,  261. 
Ckrk.    JSd.  J.  of  Sc.  7,  298;  also  Schw.  57,  421;  also  N.  Tr.  20,  1, 

243. 
Stromeyer.    Schw.  58,  123. 
Graham.     Pogg,  32.  33.    Ann.  Pharm.  29, 19. 
Gref;ory.    Preparation  of  Phosphoric  acid  from  Bone-ash.    Ann.  Pharm. 

54,  94. 
Maddrell.     On  the  preparation  of  Phosphoric  acid,  and  on  the  Metaphos- 

phates.     Mem.  Chem.  Soc.  3,  273;  Ann.  Pharm.  61,  53. 
Fownes.     Existence  of  Phosphoric  Acid  in  Rocks  of  Igneous  Origin. 

PhU.  Trans.  1844;  ahstr.  Ann.  Pharm.  60,  190. 
Sullivan.     On  the  same  subject.     PhU.  Mag.  J.  27,  161;  abstr.  Ann. 

Pharm.  60,  190. 
Rammelsberg.     Phosphates.    Pogg.  64, 251,  and  405;  abstr.  Ann.  Pharm. 

56,  210. 


103  PHOSPHORUS. 

Fleitmann  &  Henneberg.     Phoephates.     Ann,  Pharm.  65,  30— Dcmblo 

Pyrophosphates.    Ann.  Pharm,  65,  387. 
Bchwartsenberg.     Pyrophosphates.     Ann,  Pharm,  65,  133. 
PersoE.     Double  Pyrophosphates.    Ann,  Pharm,  65,  163. 
Baer.     On  certaia  Phosphates    and  Pyrophosphates.     Pogg,  75,   152; 

abstr.  Ann.  Pharm.  68,  255. 

Phosphuretted  Hydrogen, 

Gengembre.     Crell,  Ann.  1789,  1,  450. 

Kirwan.    In.  s.  Phy9.  Chem.  Schr^ten,  3,  96. 

Raymond.     Scher.  J,  5,  389. 

BerthoUet.    ^cA^jr.  .7^.  5,  396. 

Thomson.    Ann.  Phil.  8,  87;  also  Sckw.  18,  357.     Further:  Ann.  PhU. 

15,  227;  16,  262;  17,  10;  18,  120;  24,  203,  and  247. 
Dalton.     Ann.  Phil,  11,  7;  also  Schw.  24,  325. 
Houton  Labillardi^re.     Ann.  Chim.  Phys.  6,  304;  also  Schw,  21,  100. 
Vauquelin.     Ann.  Chim,  Phys.  25,  401. 
Dumas.     Ann.  Chim.  Phys,  31,  113;  also  N,  Tr,  13,  i,  145. 
H.  Rose.     Pogg.  6,  199;  8,  191;  14,  183;  24,  109,  and  295;  32,  407; 

46,  633, 
Buff.     Schw.  57,  449;  also  Po^^r.  16,363. 
Graham.     Phil.  Mag,  J,  5,  401;  also  J,  pr.  Chem,  3,  400;  abstr.  Ann. 

Pharm.  13,  141. 
Leverrier.    Ann.  Chim.  Phys.  60,  174;  also  Ann.  Pharm,  18,  333. 
Paul  Thenard.      if.  Ann.  Chim.  Phys.  14,  5;  Ann,  Pharm,  55,  27; 

abstr.  Ann.  Pharm.  52,  238. 

Metallic  Phosphides. 

Pelletier.     CreU.  Ann.  1796,  2, 148. 

Grotthuss.    Ann.  Chim.  64,  19;  also  if.  Gehl,  5,  699. 

H.  Rose.     Pogg,  24,  318. 

Landgrebe.    Schw.  53,  460;  55,  96. 

Berthier.    Ann,  Chim.  Phys.  33,  180. 


KunckeVs  Phosphorus,  Brandies  Phosphorus,  Phosphor^  Phosphors^ 
Phosphorus  Urino}. 

History.  Brandt,  of  Hamburg,  accidentally  discovered  phosphorus  in 
1669 ;  Marggraf  in  1740  demonstrated  the  individuality  of  phosphoric  acid, 
which  bad  been  regarded  by  Scheele  as  phlogisticated  muriatic  acid.  Gahn, 
in  1769,  pointed  out  the  existence  of  this  acid  in  bones;  and  Scheele  de- 
yised  a  process  for  extracting  it.  Lavoisier  first  proved  the  separate  exis- 
tence of  phosphorous  acid,  which  had  been  previously  noticed  by  Sage;  Pel- 
letier gave  a  process  for  obtaining  it  by  the  slow  combustion  of  phosphorus ; 
Fonrcroy  &  Vauquelin  examined  the  compounds  of  the  acid  thus  formed  ; 
Dulong,  however,  showed  that  it  is  a  mixture  of  phosphorus  and  phos- 
phoric acid, — and  that  pure  phosphorous  acid  in  the  hydrated  state  can 
only  be  obtained  by  the  method  devised  by  Davy.  Dulong  likewise 
discovered  hypophosphorous  acid.  Lavoisier,  Val.  Rose,  Thenard,  Ber- 
.leliui,  Dulong,  Tnomson,  Davy,  and  H.  Rose  determined  the  composition  of 
the  acids  of  phosphorus.     The  isomeric  modifications  of  phosphoric  acid, 


PHOSPHORUS.  lOS 

tiM.f  thi  pjrrophosphorio  and  metaphosphorio  acids,  werd  examined  bj 
Oay^Lossac,  Ciark,  Stromeyer,  and  more  partioalarlj  by  Graham.  Pe*> 
l6u>e  showed  that  the  red  Bobstance  formerly  examined  by  fiockmann, 
Tli4nafd|  and  A.  Vogel,  is  really  an  oxide  of  phosphorus.  Gengembre  in 
1783,  and  Kirwan  in  1784  discovered  phosphuretted  hydrogen  gas,  which 
Davy  in  1812  obtained  in  a  less  inflammable  state:  this  modification  of 
the  gas  was  afterwards  more  minately  examined  by  H.  Rose.  PellO- 
tier  examined  a  great  many  metallic  phosphides. 

Sources.  Phosphorus  occurs  in  tolerably  largo  quantity,  almost 
always  in  the  form  of  phosphoric  acid,  in  combination  with  various  bases, 
in  all  the  three  kingdoms,  but  especially  the  animal ;  rarely  as  phosphu- 
retted hydrogen ;  also  in  the  meteoric  iron  of  Bohumiliz,  Buenos  Ayres, 
And  Gotha. — Also  in  various  rooks  of  igneous  origin.  (Fownes;  Sullivan.) 

Fteparation,  A  mixture  of  charcoal  with  phosphoric  acid  con- 
taining lime,  or  of  charcoal  and  phosphate  of  lead,  is  placed  in  ftn 
Mfthen  retort — ^a  number  of  which  are  generally  arranged  side  by  side 
in  a  reverberatory  furnace  {Qaleeren-ofen) — and  distilled  at  a  heat 
gradually  rising  to  whiteness.  The  carbon  then  deprives  the  phosphoric 
acid  of  its  oxygen — is  itself  thereby  converted  into  carbonic  oxide  which 
escapes  as  gas — and  sets  the  phosphorus  at  liberty.  {Sch,  83.)— The 
neck  of  the  retort  is  usually  connected  with  a  copper  tube  bent  knee- 
shape,  and  having  its  further  extremity  immersed  to  the  depth  of  a  line 
in  water  contained  in  a  two-necked  receiver.  The  phosphorus  condenses 
below  the  surface  of  the  water,  while  the  carbonic  oxide  gas  passes  off 
through  the  second  opening  of  the  receiver,  which  is  provided  with  an 
escape- tube  directed  upwards.  The  carbonic  oxide  gas  is  mixed  with 
vapour  of  phosphorus,  and  likewise  with  phosphuretted  hydrogen,  the 
quantity  of  which  is  greater  as  the  mixture  of  charcoal  and  phosphoric 
acid  contains  a  larger  proportion  of  water.  Pure  phosphoric  acid  is  not 
so  well  adapted  to  the  purpose  as  that  which  contains  lime, — according  to 
Javal  {Ann,  Chim.  Phy$,  14,207),  because  it  partly  volatilizes  undecom- 
pose<i,-'^«ccording  to  Graham  (Lehrb,  2,  172,)  because  it  cannot  be  so 
completely  deprived  of  water,  and  therefore  yields  a  greater  quantity  of 
phosphuretted  hydrogen. 

1 .  From  human  urine,  inasmuch  as  this  liquid  contains  phosphate  of 
ammonia  and  phosphate  of  soda;  a.  The  urine,  evaporated  to  the  con- 
sistence of  honey,  is  distilled,  either  by  itself,  or  mixed  with  sand  or  char- 
coal powder.  (Brandt;  Boyle.)  In  this  process,  the  carbon — either  that 
which  is  produced  by  the  decomposition  of  the  orgitnic  matter  in  the  urine, 
or  that  which  is  added  to  it-decomposes  only  that  portion  of  phosphoric 
acid  which  is  in  combination  with  ammonia,  not  that  which  is  combined 
with  soda. — 6.  Marggraf  mixes  the  urine,  evaporated  to  the  consistence  of 
honey,  with  0*1  chloride  of  lead  and  0*5  charcoal  powder,  and  heats  the 
mass  till  it  becomes  pulverulent,  then  distils  it»  The  chloride  of  lead  and 
phosphate  of  soda  yield,  by  double  decomposition,  chloride  of  sodium  and 
phosphate  of  lead. — c.  Giobert  mixes  the  urine,  not  evaporated,  with 
nitrate  (or  acetate)  of  lead ;  the  precipitate,  which  consists  of  phosphate, 
fiuljphate  and  chloride  of  lead,  he  washes  thoroughly;  mixes  it  with  a  fourth 
of  its  weight  of  charcoal  powder;  dries  the  mixture  in  a  pan;  and  then 
distils. 

2.  From  burnt  bones,  which  consist  for  the  most  part  of  phosphate  of 
lime;  a.  By  preparing  cAlcareont  phosphoric  aeid ;  mixing  it,  after  eon* 


104  PHOSPHORUS. 

centration  to  the  consistence  of  a  syrap,  with  one-third  of  its  weight  of 
charcoal  powder;  drying  the  mixture,  and  distilling. — a.  100  parts  of 
hone-ash  are  digested  for  a  considerahle  time  in  a  leaden  vessel  with  90 
parts  of  oil  of  yitriol  and  950  of  water :  the  solution  filtered  through  linen^ 
evaporated  to  a  syrup^  mixed  with  20  parts  of  charcoal  powder,  and 
dried,  yields  10  parts  of  phosphorus.  fFuncke,  Br,  Ardi,  3,  204.) — 
$.  A  mixture  of  3  parts  hone-ash,  2  parts  oil  of  vitriol,  and  16  parts  water, 
is  similarly  treated,  and,  after  heing  concentrated  to  a  syrup,  mixed  with 
f  parts  clmrcoal  to  a  doughy  consistence.  The  mixture  is  then  heated  to 
redness,  with  constant  stirring,  in  an  iron  vessel,  and  when  cool,  put  into 
the  retort  as  quickly  as  possible.  (Graham.) — y.  Nicolas  uses  equal 
weights  of  bone-ash  and  oil  of  vitriol. — ^.  Scheele  dissolves  the  bone-ash 
in  nitric  acid,  precipitates  the  lime  by  sulphuric  acid,  filters,  concentrates, 
he, — h.  By  preparing  phosphate  of  lead,  and  distilling  it  with  \  of  its 
weight  of  charcoal  ;  a.  Fourcroy  &c  Vau^uelin  prepare  acid  phosphate  of 
lime  by  Nicolas's  method,  and  precipitate  its  aqueous  solution  with  acetate 
of  lead. — /3.  Berzelius  dissolves  the  bone-asb  in  warm  nitric  acid,  and 
mixes  it  while  still  hot  with  acetate  of  lead.  Native  phosphate  of  lead 
may  also  be  used,  provided  it  is  free  from  arseniate. 

Two  parts  of  bone-black  mixed  with  one  part  of  fine  auartz-sand,  and 
raised  to  a  strong  white  heat  in  an  earthenware  tube,  yield  carbonic  oxide 
and  a  small  quantity  of  phosphorus.  (Wohler,  Pogg,  17,  178.)  The 
affinity  of  silicic  acid  for  lime  assists  the  decomposing  action  of  the  char- 
coal on  the  phosphoric  acid  combined  with  the  lime. 

The  phosphorus  which  passes  over  is  freed  from  adhering  charcoal  and 
red  phosphoric  oxide  by  pressing  it  between  chamois-leather  under  warm 
water;  or  by  distillation  in  a  glass  retort  the  neck  of  which  dips  under 
water.     It  is  then  melted  in  glass  tubes  and  formed  into  sticks.* 

The  phosphorus  of  commerce  frequently  contains  arsenic,  as  was  first 
observed  by  Hertz  <fe  Barwald.  {Berl.  Jahrh  32,  2,  113.)  For,  if  the  oil 
of  vitriol  used  in  its  preparation  has  been  formed  by  the  combustion  of 
arsenical  sulphur,  it  will  contain  arsenious  acid ;  and  when  bone-ash  is 
decomposed  by  it,  the  arsenious  acid  will  mix  with  the  phosphoric  acid ; 
consequently,  when  the  mass  is  heated  with  charcoal,  the  arsenic  will  be 
reduced  to  the  metallic  state  and  will  pass  over  with  the  phosphorus.  In 
one  sample  of  phosphorus,  Wittstock  found  0*76  per  cent,  of  arsenic. 
(Berl  Jahrb.  32,  2,  125;  abstr.  Fogg.  31,  126.)  Phosphorus  of  this 
description  has  the  same  tenacity  and  the  same  colour  as  pure  phosphorus ; 
but  the  surface,  when  freed  from  the  white  crust,  is  of  a  smoky  yellow 
colour,  while  the  inner  portion  exhibits  the  pale  yellow  tint  of  pure  phos- 
phorus. It  cannot  be  purified  by  distillation,  for  tbo  arsenic  passes  over 
with  it.  It  is,  like  the  latter,  perfectly  soluble  in  bisulphide  of  carbon,  but 
the  solution  soon  deposits  a  rod  sediment,  consisting  of  bisulphide  of  carbon 
and  phosphoric  oxide.  To  water  under  which  it  is  kept  for  some  time,  it 
imparts  arsenious  acid.  (Wittstock.)     If  it  be  digested  for  half  an  hour 

*  An  appantos  by  which  the  last-mentioned  part  of  the  process  may  be  performed 
on  the  large  scale  with  great  regularity  and  expedition,  is  described  by  Seubert,  Ann, 
Pharm.  49,  346.  It  consists  of  a  copper  vessel  in  which  the  phosphorus  is  melted,  and 
firom  which  it  flows  into  glass  tubes  placed  horizontally,  and  having  half  their  length— 
that  towards  the  copper  vessel — surrounded  with  warm  water,  the  other  half  with  cold. 
The  phosphorus,  as  it  solidifies  in  the  cold  part  of  the  tubes,  is  drawn  out;  a  fresh 
quantity  flows  fix>m  the  receiver  to  supply  its  place;  this,  in  its  turn,  is  solidified  and 
drawn  out;  —and  thus  a  stick  of  phosphorus  is  formed  of  any  required  lengtii.  By  this 
method  from  15  to  201bs.  of  phosphorus  may  be  formed  into  sticks  in  a  quarter  of  an 
hour.    The  memoir  is  acoompanied  by  a  figure  of  the  apparatus.     [  W.] 


PHOSPHORUS.  105 

with  2  parts  of  nitric  acid  of  specific  gravity  1*1^  the  acid  takes  up  the 
greater  part  of  the  arsenic^  which  may  then  be  easily  recognised  by  means 
of  sulphuretted  hydrogen  (Barwald) ;  but  it  is  only  when  the  phosphorus 
has  been  digested  with  continually  renewed  quantities  of  dilute  nitric  acid, 
till  it  is  reduced  to  ^  of  its  original  bulk,  that  it  can  be  considered  per- 
fectly free  from  arsenic.  (Wittstock.)  When  the  solution  of  this  impure 
phosphorus  in  dilute  nitric  acid  is  evaporated^  it  becomes  turbid  at  a  cer- 
tain degree  of  concentration^  in  consequence  of  the  complete  separation  of 
the  arsenic  in  the  form  of  a  black  powder,  its  reduction  being  effected  by 
the  phosphorous  acid  present  and  the  phosphuretted  hydrogen  evolved 
when  it  is  heated.  (Barwald,  Wittstock :  compare  Dalk,  Berl.  Jahrb, 
34,  1,  247;  Wackenroder,  J,  pr,  Ckem.  2,  340;  Liebig,  Ann.  Fharm, 
11,  260.) 

A  sample  of  phosphorus  obtained  from  France  was  covered  with  a 
greyish-yellow  coatiug  instead  of  a  white  one;  appeared,  when  freed  from 
this  coating,  of  a  dark-red  colour  by  transmitted  li^ht ;  was  almost  black 
on  the  fractured  surface ;  and  retained  this  colour  wnen  melted  and  slowly 
solidified.  It  contained,  besides  arsenic,  bismuth,  lead,  iron,  and  copper — 
a  particularly  large  quantity  of  antimony;  and  when  dissolved  in  bisul- 
phide of  carbon,  deposited  black  flakes  of  sulphide  of  antimony.  (Witt- 
stock, Berl.  Jahrb.  33,  2,  146.) 

Many  specimens  of  phosphorus  are  yellow  in  the  fused  state,  but  turn 
black  on  cooling,  especially  when  suddenly  cooled.  Boiling  in  alcohol 
destroys  this  property:  on  the  other  hand,  phosphorus  acquires  it  by 
being  fused  with  phosphoric  acid.  (Bonz,  Crell.  Ann.  1788,  1,  392; 
Th^nard.) 

Phosphorus,  otherwise  pure,  generally  contains  a  small  quantity  of 
phosphoric  oxide,  which  gives  it  a  yellowish  or  reddish  colour.  ( Vid, 
p.  108.)  To  free  it  from  this  oxide  and  obtain  it  colourless,  the  following 
methoas  may  be  applied : 

1.  By  digesting  it  for  a  considerable  time,  with  frequent  a&^tation,  in 
very  dilute  nitric  acid  contained  in  a  flaak  fitted  with  a  gas-delivery  tube 
which  dips  under  water.  The  phosphoric  oxide  is  then  converted  into 
phosphorous  and  phosphoric  acid  more  quickly  than  the  phosphorus. 
Chlorine  water  acts  in  a  similar  manner. 

2.  By  heating  the  phosphorus  in  a  solution  of  potassa  or  ammonia, 
and  then  in  water. 

3.  By  heating  it  in  a  solution  of  hydrate  of  potassa  in  alcohol  of  75 
per  cent.,  whereby  it  is,  in  a  few  minutes  only,  converted  into  a  clear 
watery  liquid.  Phosphorus  thus  treated  does  not  solidify  under  the  solu- 
tion of  potassa  for  several  weeks  at  ordinary  temperatures;  but  at  — 2*5® 
it  solidifies  rapidly,  and  subsequently  fuses  at  its  ordinary  melting  point. 
If  poured  upon  blotting-paper,  it  solidifies  as  soon  as  the  adhering  solution 
has  sunk  into  the  paper,  and  with  particular  rapidity  when  touched  with 
an  iron  wire.  On  pouring  off  the  solution  of  potassa  and  sprinkling  the 
phosphorus  with  water  as  cold  as  can  be  procured,  it  instantly  solidifies 
to  a  snow-white,  easily  crumbling  mass  of  crystalline  texture.  When 
more  slowly  cooled  by  water,  it  solidifies  to  a  white  mass  of  waxjr  con- 
sistence. U  this  white  phosphorus  be  strondy  heated  with  solution  of 
potassa,  then  freed  from  the  liquid  after  the  lapse  of  throe  minutes, 
and  several  times  sprinkled  with  very  cold  water,  it  is  obtained,  sometimes 
perfectly  transparent,  sometimes  only  translucent.  (E.  Bbttger,  Schw, 
67,  141.) 

4.  Ten  parts  of  phosphorus  are  added  to  one  part  of  bisulphide  of  carbon 


106  PHOSPHOBVI. 

placed  below  alcobol  of  80  per  oent. :  the  phodpborns  disedltes,  whiUt 
the  phosphoric  oxide  and  the  white  crast  rise  to  the  snrfiMe  of  the  solution. 
About  1 1  parts  of  solution  of  potassa  are  then  added,  and  heat  applied  for 
about  tight  minutes,  till  the  white  and  red  substances  are  dissolved,  and  the 
bisulphide  of  carbon  is  converted  into  xanthonate  of  potassa.  After  cooliuf, 
the  alkaline  liquid  is  poured  off — the  phosphorus  repeatedly  washed  with 
cold  water — heated  under  alcohol  containing  a  small  quantity  of  potassa, 
till  all  the  bisulphide  of  carbon  is  expelled  (the  presence  of  sulphide  of 
carbon  makes  the  phosphorus  crumbly  and  even  pappy),  and  washed  with 
cold  water*  Phosphorus  thns  purified  appears  snow-white  when  suddenly 
cooled,  but  perfectly  transparent  after  slow  cooling. 

Phosphorus  should  be  kept  in  the  dark  in  vessels  filled  with  water. 

To  granulate  phosphorus,  it  is  shaken  up,  while  in  the  fused  state, 
with  a  warm  liquid  till  it  solidifies.  For  this  purpose,  according  to 
Cassarca,  (J.  Fhann.  16,  202),  alcohol  of  36°  B.  is  better  adapted  than 
water.  According  to  Bbttger  {Beitrdge,  1,  Qo-,  2,  127),  the  liquid  which 
reduces  phosphorus  to  the  finest  state  of  granulation  is  human  urine; 
and  it  derives  this  property  from  the  urea  which  it  contains,  so  that  an 
aqueous  solution  of  artificial  urea  may  be  used  as  a  more  cleanly  substi- 
tute for  the  urine.  A  tall  cylinder  an  inch  wide  is  half  filled  with  a 
liquid  of  this  kind,  and  heat  applied  till  the  phosphorus  introduced  into 
it  is  melted :  the  phosphorus  is  then  worked  about  for  two  minutes,  by 
means  of  a  twirling  stick  which  passes  through  the  opening  of  the  wooden 
cover  of  the  cylinder;  it  is  thus  brought  into  a  fine  state  of  division.  The 
remaining  portion  of  the  cylinder  is  then  filled  with  cold  water,  the 
twirling  motion  being  continued  all  the  while.  When  the  liquid  comes 
to  rest,  the  phosphorus  is  deposited  in  the  state  of  powder;  the  liquid  is 
then  poured  off,  and  the  phosphorus  washed  with  water. 

Properties,  Phosphorus  is  colourless,  transparent  after  alow  cooling, 
semi-opaque  after  rapid  cooling,  and  has  a  waxy  lustre.  It  crystallizes 
in  regular  octohedrons  and  rhomboidal  dodecahedrons.  Considerable 
masses  of  phosphorus,  when  they  solidify  after  fusion,  yield  dodecahedrons 
and  octohedrons  as  large  as  peas.  H'rautvrein,  Buchner,  Kastn,  Arch.  10, 
127,  and  504;  Repert.  25,  481.)  From  a  solution  in  volatile  oils,  phos- 
phorus crystallizes  in  octohedrons  (Pelletier) ;  and  from  solution  in  sul- 
phide of  phosphorus,  in  dodecahedrons.  (Mitscherlich.)  Specific  gravity 
=  1-896,  Bockmann,  20832,  Foureroy,  2089  at  17°  (that  which  has 
been  purified  by  an  alcoholic  solution  of  potash),  B'dUger,  It  is  brittle  in 
the  cold,  but  of  a  waxy  consistence  at  ordinary  temperatures.  At  34*33^ 
it  becomes  brittle,  and  eas^  to  pulverize;  melts  at  44'5  (J.  Davy,  N.  Ed. 
Phil.  J.  6,  130);  after  fusion  it  cools,  if  at  rest,  down  to  37'5*  before  it 
solidifies ;  and  when  solidification  takes  place,  the  temperature  rises  to 
45*'.  (Pelletier.)  According  to  Heinrich,  it  fuses  at  46*25",  and  solidifies 
at  40^  its  temperature  then  rising  again  to  46*25^.  In  the  fused  state  it 
presents  the  appearance  of  a  transparent  oil.  Melted  phosphorus,  when 
at  rest,  often  remains  liquid  considerably  below  its  melting  point  (I.,  9  and 
II.  105^;  freauently  even  as  low  as  4°  :  under  these  circumstances,  con- 
tact with  a  solid  body,  especially  with  phosphorus,  causes  it  to  solidify. 
(Bellani,  G^torn.  dijlstea,  1813;  also  N.  Qmrt  J.  2,  469;  H.  Rose,  Pogg. 
82,  469.)  This  phenomenon  is  particularly  remarkable  with  phosphorus 
boiled  in  an  aqueous  or  alcoholic  solution  of  potassa,  which  remains  liquid 
for  days  and  then  solidifies  on  being  agitated.  Grotthuss  {N.  Oehl,  9, 
228)  liicewise,  on  heating  pbosphonis  with  alcoholic  solution  of  potassa, 


PHOSPHORUS.  107 

obtained  it  in  tbe  form  of  an  oil  which  did  not  ftolidify  on  oooline,  and 
when  heated  in  contact  with  water,  erolred  phosphoretted  hycunogeo, 
without  introducing  phosphoric  acid  into  the  water :  hence  he  concluded 
that  the  oil  must  be  a  oompound  of  phosphorus  and  hydrogen. 

Phosphorus  boils  at  250*'    (Heinrioh),  at   288^   (Dalton),  at  200« 

SPelletier,  Ann.  Chim,  4,  B),  and  is  converted  into  a  colourless  vapour. 
Specific  gravity  of  the  vapour,  p.  279,  Tol.  I.)  Phosphorus  volatilizes 
at  temperatures  considerably  below  its  boiling  point,  not  only  when  boiled 
with  water,  in  which  case  it  makes  the  aqueous  vapour  luminous,  but  in 
small  quantities,  even  at  ordinary  temperatures,  either  in  vacuo  or  in  a 
space  filled  with  air  (I.,  265,  266).  Oxygen,  hydrogen,  carbonic  oxide, 
hydrosulphuric  acid,  nitrogen,  dltc,  and  likewise  carbonic  acid  gas,  (accord- 
ing to  Davy,  but  not  according  to  Fouroroy  &  Vauquelin)  when  placed  in 
contact  with  pliosphorus,  become  charged  with  its  vapour.  The  faint 
luminosity  said  to  bo  observed  when  phosphorus  volatilises  in  nitrogen 
gas  is  due,  according  to  Berthollet,  to  a  trace  of  oxygen  introduced 
through  the  water  which  confines  the  gas,  and  giving  rise  to  a  slow  com- 
bustion. Berthollet  asserts  that  nitrogen  gas,  by  taking  up  vapour  of 
phosphorus,  increases  in  volume  by  ^ ;  but  according  to  Bronner  {Ann, 
Chem,  Phys.  78,  316),  no  perceptible  increase  takes  place,  inasmuch  as  the 
quantity  of  phosphorus  which  volatilises  at  ordinary  temperatures  is  ex* 
tremely  small,  not  amounting  to  one  milligramme  in  1782  cuoic  centimetres. 
Phosphorus,  both  in  the  solid  aud  in  the  liquid  state,  is  a  non-con-^ 
ductor  of  electricity.  According  to  Knox  {FkU.  Mag.  J.  16,  18*^), 
melted  phosphorus  conducts  the  current  of  a  60-pair  battery  with  pUtes 
5  square  inches  in  surface. 

Phosphorus,  when  exposed  to  the  air,  smells  like  garlic ;  in  the  state 
of  solution  it  has  a  sharp  and  repulsive  taste,  and  acts  as  a  violent 
irritant  poison.     It  is  highly  inflammable. 

White  Pho9pkoru$,  Phosphorus,  kept  under  water  and  exposed  to 
sunshine  or  ordinary  daylight,  gradually  becomes  covered  with  an  opaque 
crust,  which  is  reddish-yellow  at  first  but  afterwards  turns  white,  has  a 
specific  gravity  1*515  at  15°  (Pelonze),  smells  like  phosphorus,  shines  in 
the  dark  on  exposure  to  the  air,  but  turns  red  in  daylight  more  quickly 
than  colourless  phosphorus.  This  white  phosphorus  retains  its  original 
appearance  when  dried  over  oil  of  vitriol;  but  at  a  temperature  not 
amounting  to  50°,  it  changes  into  transparent  melted  phosphorus,  and 
that  too  without  losing  water  or  sustaining  any  diminution  of  weight. 
The  white  variety  is  therefore  pure  phosphorus;  differing  from  the 
transparent  kind  only  in  its  state  of  aggregation.  (H.  Rose,  Fogg,  27, 
563.)  Marchand  {J.  pr,  Ohem,  20,  506)  finds  that  white  phosphorus 
dried  over  oil  of  vitriol  loses  by  fusion  only  from  0*4  to  0*7  per  cent,  of 
water.  Pelouze  {Ann,  Ghim,  Phys,  60,  83),  who  dried  white  phosphorus 
without  oil  of  vitriol,  found  that  when  fused  it  lost  12  per  cent,  of  water: 
he  therefore  regarded  it  as  a  Hydrale  of  Phosphorus  =  P*,  HO.  Mulder 
{J.  Pharm,  23,  20;  also  J.  pi\  Chem.  13,  883)  regards  it  as  a  compound 
of  phosphoric  oxide  and  phosphuretted  hydrogen,  produced  by  decompo- 
sition of  water — because  it  turns  red  in  water  containing  air.  This  red- 
dening was  not  observed  by  Marchand,  not  even  when  oxygen  gas  was 
passed  through  the  water.  Mulder's  result  was  probably  due  to  the 
action  of  light.  The  production  of  white  phosphorus  may  perhaps  be 
explained  on  the  supposition  that  phosphorus,  under  the  infiuence  of  liffht, 
decomposes  water,  producing  phosphoric  oxide  and  phosphuretted  hydro- 
gen, and  that»  in  the  dark,  these  two  compounds  are  again  resolvea  into 


108  PHOSPHORUS. 

water  and  finely  diyided  phosphorns.  At  all  events,  phosphorns  retaina 
its  transparency  when  constantly  kept  under  water  in  the  dark.     (Gm.) 

IT  Bed  I^Msphorus.  AmorphouB  Pkosp1u>rus,  This  modification  of 
phosphorus  has  heen  already  noticed  on  pa^  105,  the  author  there  speaking 
of  it  as  phosphoric  oxide.  It  is  produced  when  phosphorus  is  exposed 
to  light,  either  under  water  or  alcohol,  or  in  vacuo  (even  the  Torricellian 
vacuum),  or  in  hydrogen,  nitrogen,  carhonic  acid,  carburetted  hydrogen, 
or,  in  short,  any  gas  not  containing  oxygen.  For  this  reason  it  was 
regarded  by  Berzelius,  not  as  phosphoric  oxide,  but  as  phosphorus  in  a 
peculiar  a/&<r(>/>i<^  condition;  while  those  who  consider  it  as  an  oxide 
attribute  its  formation,  under  the  circumstances  just  mentioned,  to  the 
presence  of  moisture  not  completely  removed  from  it  previously  to  its 
introduction  into  the  several  gases.  The  subject  has  lately  been  more 
particularly  investigated  by  Schrotter  (N,  Ann,  Chim.  Fhys.  24,  406; 
abstr.  Ann,  Fharm.  68,  247),  who  has  shown,  in  a  variety  of  ways,  that 
the  red  substance  in  question  is  nothing  but  pure  phosphorus  in  a 
peculiar  state  of  aggregation.  Perfectly  pure  colourless  phosphorus,  dried 
as  completely  as  possible,  was  placed  in  a  glass  tube  having  a  bulb  in 
the  middle;  dry  carbonic  acid  gas  passed  over  it;  the  phosphorus  gra- 
dually heated  to  100*,  to  drive  off  every  trace  of  moisture;  and  the  tube 
sealed  at  both  ends :  by  this  means  every  trace  of  oxygen  was  excluded. 
Nevertheless  it  was  found  that  the  phosphorus,  when  exposed  to  light, 
assumed  a  red  colour,  the  depth  of  which  increased  with  the  intensity  of 
the  light.  The  colouring  did  not  extend  to  the  whole  mass,  but  was  due 
to  the  formation  of  a  multitude  of  small,  separate,  red  particles.  The 
same  results  were  obtained  in  hydrogen  or  nitrogen  gas.  It  appears, 
then,  that  light  produces  in  phosphorus  a  peculiar  change  of  conoUtion, 
which  cannot  be  ascribed  to  oxidation. 

The  same  efiect  is  produced  by  heat.  A  glass  bulb  was  attached  by 
fusion  to  the  neck  of  a  retort,  and  a  quantity  of  dzy  phosphorus  placed 
both  in  the  body  of  the  retort  and  in  tne  bulb ;  the  extremity  of  the  neck 
was  connected  with  a  glass  tube  more  than  30  inches  long,  placed  verti- 
cally, and  with  its  lower  end  dipping  under  mercury.  The  neck  of  the 
retort  above  the  bulb  was  filled  with  chloride  of  calcium,  and  a  thermo- 
meter inserted  through  the  tubulure.  The  apparatus  being  thus  arranged, 
the  phosphorus  in  the  bulb  was  heated  till  it  took  fire,  and  thus  absorbed 
all  the  oxygen  contained  in  the  air  of  the  retort.  The  body  of  the  retort 
was  then  heated  to  100%  to  drive  off  any  moisture  adhering  to  the  phos- 
phorus, and  then  left  to  cool.  After  this,  the  phosphorus  was  slowly 
neated.  Sublimation  began  at  150^,  but  without  change  of  colour.  At 
226°  (439°  F.),  the  phosphorus  after  a  while  assumed  the  colour  of  car- 
mine; it  likewise  became  thicker,  and  the  colour  continually  increased  in 
intensity,  till  at  length  perfect  opacity  was  produced.  This  change  of 
character  was  due  to  the  separation  of  a  red  powder,  which  at  first  settled 
down  to  the  bottom  of  the  vessel,  but  rapidly  increased  in  quantity  till  it 
extended  through  the  whole  mass.  When  the  phosphorus  was  kept  from 
48  to  60  hours  at  a  temperature  between  240°  and  250°,  a  solid  stratum 
of  amorphous  phosphorus  was  formed  at  the  bottom  of  the  vessel,  and 
above  it  a  mixture  of  ordinary  phosphorus  with  a  considerable  quantity 
of  the  amorphous  variety.     The  change  takes  place,  though  slowly,  at 

*  The  tenn  Alhtropy  has  lately  been  brought  into  use  to  denote  the  different  states 
in  which  the  same  sabstanoe  may  exist  without  alteration  of  chemical  oonstitation:  thus, 
diamond,  graphite^  and  charcoal  are  allotropic  conditions  of  carbon ;  the  octohedral,  pris- 
matic, and  plastic  states  are  allotropic  conditions  of  sitlphor ;  &c.    [W.] 


PHOSPHORUS.  109 

215°;  bat  it  is  most  rapid  between  240*'  and  250°.  It  is  accelerated  by 
tbe  action  of  light.  Under  diminished  pressure  the  conversion  is  slower, 
and  does  not  appear  to  be  produced  at  all  when  the  pressure  is  reduced 
below  393""  (15^  in.).*  Eight  ounces  of  ordinary  phosphorus  heated  for 
50  bours  in  the  manner  above  described  yielded  6  oz.  of  amorphous 
phosphorus.  The  latter  may  be  separated  m>m  ordinary  phosphorus  by 
digestion  in  bisulphide  of  carbon,  which  dissolves  the  ordinary  but  not 
the  amorphous  phosphorus.  The  undissolved  portion  must  be  collected 
on  a  filter,  and  thoroughly  washed  with  bisulphide  of  carbon.  For  com- 
plete purification,  the  residue  is  to  be  boiled  in  caustic  potash  of  density 
1*3,  and  then  washed,  first  with  water  slightly  acidulated  with  nitnc 
acid,  and  afterwards  with  pure  water. 

Amorphous  phosphorus  thus  obtained  is  a  soft  powder  destitute  of 
crystalline  structure,  varying  in  colour  between  carmine  and  scarlet, 
sometimes  even  of  a  blackish-brown  tint.  When  heated  in  a  liquid,  it 
becomes  darker,  and  after  some  time  acquires  a  deep  violet  colour.  Its 
specific  gravity  at  10^  is  1*964;  that  of  ordinary  phosphorus  melted  at 
45°  is  1-88,  and  in  the  solid  state,  1*840. ...1-826.  (Schrotter.)  Amorpbrnis 
pbospborus,  by  repeated  distillation  in  an  atmosphere  of  carbonic  acid,  is 
converted,  withotit  loss  of  weight,  into  ordinary  phosphorus — a  proof  that 
it  is  really  pure  phosphorus,  and  not  an  oxide :  the  change  takes  place  at 
260°  (500^  F.).  It  is  unalterable  in  the  air,  insoluble  in  bi-snlphide  of 
carbon,  alcohol,  ether,  rock-oil,  and  ter-chloride  of  phosphorus.  Oil  of 
turpentine,  and  other  liquids  of  high  boiling-point,  dissolve  small  quan- 
tities of  it  when  heated ;  but  when  deposited  from  them  on  cooling,  it  is 
re-conyerted  into  ordinary  phosphorus.  It  does  not  shine  in  the  dark  till 
beated  nearly  to  the  point  at  which  it  takes  fire  (near  500°  F.).  Con- 
centrated sulphuric  acid  has  no  action  upon  it  in  the  cold — ^but,  on  the 
application  of  heat,  dissolves  it,  with  evolution  of  sulphurous  acid.  Nitric 
acid  dissolves  it  readily.  It  decomposes  many  metallic  oxides ;  e.  g,  the 
oxides  of  manganese,  lead,  silver,  copper,  and  mercury,  with  the  aid  of 
friction  or  heat — sometimes  with  explosion. 

It  appears  then  that  phosphorus,  like  sulphur  and  carbon,  can  exist 
in  three  allotropic  conditions  :  (1)  Ordinary  transparent,  nearly  colour- 
less phosphorus,  which  is  really  of  crystalline  structure-— though  that 
structure  is  not  seen  in  phosphorus  solidified  in  the  ordinary  way  from  a 
state  of  fusion,  because  in  solidifying  it  passes  through  the  viscid  state, 
which  is  inimical  to  crystallization.  (2)  White,  opaque  phosphorus, 
already  described  (p.  107),  produced  by  the  action  of  light  upon  phosphorus 
nnder  water :  this  is  also  a  crystalline  modification.  (3)  Ked  amor- 
phous phosphorus,  produced  by  the  action  of  light  or  heat  in  the  manner 
just  detailedf.  (Schrotter.) 

*  The  limitation  here  spoken  of  mnat  refer  to  the  action  of  heat  alone,  without 
light;  for  in  presence  of  light  the  change  takes  place  even  in  the  Torricellian  va- 
cuum.    [W.] 

t  It  is  possible  t^t  even  a  fourth  modification  of  this  element  may  exist,  viz.,  the 
yellow,  semitransparent  state  which  it  always  acquires  when  kept  for  some  time  under 
water.  Napoli  {Compt,  rend.  64,  252.)  remarks  that  the  want  of  transparency  here 
spoken  of  arises  not  from  impurity,  but  from  a  peculiar  state  of  molecular  aggregation. 
This  state  may,  however,  be  only  intermediate  between  the  transparent  and  the  white 
opaque  varieties  (1)  and  (2).  W Shier  {Ann.  Pharm.  45,  249)  states  that  either  this 
yellow  phosphorus  or  the  red  amorphous  variety  may  be  rendered  colourless  and  trans- 
parent like  glass,  by  fusing  it  in  a  concentrated  solution  of  bichromate  of  potassa  mixed 
with  sulphuric  acid.    To  ensure  contact,  the  bottle  should  be  closed  and  well  shaken 


110  FHO«raOEU8. 

Tb«  atomic  weight  of  pkoaphom  hao  boon  lutoly  dotormined 
PelooM  to  bo  400'd  on  tho  oxygen  acale,  or  82  on  the  hydjrogtn  aoalo. 


C(>mp<mnd$  of  Photphorvs. 

PHOePROEUS  AND  OxTOEH. 

A.    Phosphoric   oxide.    PO. 

Jted  Phosphoric  matUr.    Oxide  of  P/iosphorw,  Phoiphoroxyd. 

Formation.  1.  When  phosphorus— either  in  vacuo,  or  in  hydrogen, 
nitrogen,  carbonic  acid,  arseniaretted  hydrogen,  or  marsh-gas,  or  in 
alcohol  or  water, — is  exposed  to  colourless  or  yiolet  light. — In  vacuo  and 
in  the  above-named  gases,  phosphorus  first  volatilizes,  and  then  settles 
<m  the  sides  of  the  glass  vessel,  provided  they  are  transparent,  in  the 
form  of  a  brown-red  substance. — In  nitric  oxide  gas,  phosphorus  becomes 
covered,  not  with  a  red  but  with  a  white  coating :  in  sulphide  of  carbon 
and  sulphide  of  phosphonis  also,  phosphorus  does  not  redden.  The  light 
of  burning  sulphur  and  of  the  Indian  white  fire  likewise  do  not  redden 
phosphorus.  (Bockmann,  A.  Vogel.)— Whence  the  oxygen  required  for  the 
formation  of  the  oxide  is  derived,  when  the  phosphorus  is  placed  in  the 
above-mentioned  gases,  is  not  clearly  made  out :  it  is  probable,  how- 
ever, that,  in  the  experiments  just  described,  water  was  not  completely 
excluded,  and  was  converted  by  the  phosphorus,  under  the  influence  of 
light,  into  phosphono  oxide  and,  phosphuretted  hydrogen.  (See  p.  108.) 
2.  When  phosphorus,  in  contact  with  water  or  other  compounds  of  oxy- 
gen, is  passed  through  a  red-hot  tube,  or  when  it  is  rapidly  burnt  m 
oxygen  gas,  common  air,  or  rarefied  air, — ^the  phosphoric  acid  produced 
is  mixed  with  phosphoric  oxide.  3.  By  heating  phosphorus  with  aqueous 
solution  of  iodic  or  hy periodic  acid  (Benckiser),  or  with  nitrate  of  am- 
monia. (Marchand.)  4.  On  exposing  to  the  air  a  solution  of  phosphorus 
in  terchloride  of  phosphorus  or  anhydrous  ether. 

PrepareUion.  1.  Bubbles  of  oxygen  gas  are  thrown  upon  phosphorus 
heated  under  water,  so  that  vivid  combustion  ensues.  (A.  Vogel.) — Tho 
phosphoric  acid  produced  in  this  combustion  dissolves  in  the  water ;  the 
flakes  of  oxide  which  swim  about  are  washed  and  heated  in  a  retx>rt  to 
free  them  from  water  and  unoxidized  phosphorus ;  they  are  then  washed 
a  second  time  to  remove  the  newly  formed  phosphoric  acid,  and  dried  in 
vacuo  over  oil  of  vitriol.  (Pelouze.)  Bbttger  {Ann.  Pkarm,  20,  82) 
washes  the  oxide  with  water — ^agitates  it  briskly  for  a  minute  with  a 
mixture  of  equal  measures  of  bisulphide  of  carbon  and  absolute  alcohol, 
which  dissolves  the  phosphorus ~ decants — agitates  the  oxide  a  second  time 
with  a  fresh  quantity  of  the  mixture,— collects  it  on  a  filter — washes  it  first 
with  alcohol,  then  with  water — and  dries  it,  either  in  the  open  air,  or 
under  a  glass  jar  with  oil  of  vitriol.     2.  Phosphorus  spread  in  a  thin 

till  the  phosphonis  divides  itself  into  small  globules  :  these  reunite  when  the  liquid  is 
left  at  rest.  Phosphorus  thus  treated  generally  remains  liquid  after  oooUs^,  but  solidi* 
fise  instantly  when  touched  by  any  solid  body.     [W.] 


PHOSPHORIC  OXIDE.  Ul 

layer  over  a  poroelain  eap«al«  (in  order  that  the  temperature  may  not 
rise  too  high)  ie  set  on  fire--^he  residue  freed  by  water  from  phosphoric 
acid,— ^ then  dried  and  boiled  with  terchloride  of  phosphorus  to  remove  un- 
oxidized  phosphorus — and  finally  washed  with  water  and  dried.  (Leverrier.) 
3.  Id  a  strong  glass  globe  of  the  capacity  of  about  a  pint,  and  having  a 
loD^  and  strong  tube  luted  on  to  it,  5  grammes  of  phosphorus  are  heated 
and  spread  over  the  whole  of  the  inner  surface  :  a  small  quantity  of  ni- 
trate of  ammonia  is  then  thrown  in,  and  the  part  of  the  globe  where  it 
rests  etrongly  heated  over  the  flame  of  a  spirit-lamp.    As  the  salt  decom' 
poees,  a  red  flame  shoots  out  of  the  tube,  and  the  whole  of  the  globe 
becomes  covered  with  phosphoric  oxide.     Should  any  of  the  phosphorus 
remain  nnoxidised,  more  nitrate  of  ammonia  is  introduced  and  heat  again 
applied.     After  cooling,  the  flakes  of  oxide  are  rinsed  out  with  water, 
and   when  thoroughly  washed,  they  are  heated  in  a  retort  filled  with 
hydrogen  gas  to  distil  off  the  excess  of  phosphorus.  (Marchand,  J.  pr. 
Cheia.  13,  442.)     4.  Phosphorus  is  boiled  with  solution  of  hyperiodic  or. 
iodic  acid,  or  a  mixture  of  hyperiodate  of  soda  with  dilute  nitric  acid,  or 
of  iodate  of  8oda  with  dilute  sulphuric  acid,  till  it  has  lost  its  fluidity. 
The  mixture  of  phosphorus  and  phosphoric  oxide  thus  obtained  is  then 
rubbed  to  powder  under  water  and  again  boiled  in  the  acid  liquid. — 
Iodine  is  set  free  in  the  proeess.  ( Benckiser,  ilnn.  PAarm.   17,258.)     5. 
Into    a  glass  flask  of  the  capacity  of  about  a  quart,  and  having  a 
neck  4  inches  long    and  one  inoh  wide,  there  is  introduced  a  small 
quantity  of  terchloride  of  phosphorus, — then  some  pieces  of  phosphorus 
weighing  half  a  gramme  and  dried  with  paper,  in  sufficient  quantity  to 
form  a  layer  \  of  an  inch  thick,-*-then  more  terchloride,  suflicient  to 
partially  cover  the  phosphorns.     After  twenty-four  hours*  exposure  to  the 
air,  a  thick  white  omst  of  phosphatie  acid  is  formed  on  the  surface  where 
the  access  of  oxygen  is  easiest ;  while  below  this  and  above  the  phos^ 
phorus,  there  is  produced  a  yellow  layer  of  phatpkaU  ofphoiphoric  omde, 
the  quantity  of  which  attains  its  maximum  in  twenty-four  hours'  longer. 
The  chloride  of  phosphorus,  which  may  be  used  again  for  the  same  pur* 
pose,  is  then  poured  off,   and  the  pieces  of  phosphorus  to  which  the 
phosphate  of  phosphoric  oxide  adheres,  separated  from  one  another,  and 
put  singly  into  cold  water,  so  that  no  rise  of  temperature,  which  would 
decompose  the  phosphate,  may  take  place.     The  phosphate  of  phosphorio 
oxide  dissolves  in  the  water,  forming  a  yellow  solution  which  is  poured 
off  from  the  phosphorus  and  heated  to  80^.     It  is  thereby  resolved  into 
phosphoric  acid  which  remains  dissolved,  and  hydrate  of  phogpkoTnc  oxidt 
which  falls  down  in  yellow  flakes.     The  latter  is  quickly  washed  on  a 
filter  with  warm  water,  transferred  while  yet  moist  into  a  porcelain  dish, 
and  dried  in  Tacuo  over  oil  of  vitriol :  it  then  also  loses  its  water  of 
hydration.     If  the  air  be  slowly  exhausted,  the  oxide  remains  iu  small, 
red,  partly  crystalline  grains,  which  yield  a  yellow  powder ;  if  the  ex- 
haustion be  rapidly  made,  s#  as  to  freese  the  water,  the  hydrate  gives  up 
its  wat^  suddenly, — and  when  the  ice  is  allowed  to  melt  in  the  air,  the 
oxide  settles  at  the  bottom  in  the  form  of  a  delicate  yellow  powder.    The 
oxide  thus  obtained  is  free  from  chlorine  and  hydrogen.  (Leverrier.)     By 
prooeeding  in  the  same  manner,  with  the  exception  of  using  perfectly 
anhydrous  ether  in  place  of  chloride  of  phosphorus  (if  the  ether  contains 
water,  nothing  but  phosphatie  acid  is  produced),  a  yellow  hydrate  is  ob- 
tained ;  and  this,  when  dried  under  the  air-pump,  yields  a  dry  orange- 
yellow   compound  of  90*3    phosphoric    oxide   and  9'7  organic    matter^ 
probably  ether.     This  compound  is  not  decomposed  by  boUuig  in  water— 


112  PHOSPHORUS. 

dissolyes  without  residue  in  nitric  acid, — and  when  heated  alone  or  set 
on  fire  in  the  air,  leaves  a  carbonaceous  residue.     (Leverrier.) 
Phosphoric  oxide  must  be  kept  in  a  dry  atmosphere. 

Properties.  The  oxide  prepared  according  to  {5)  is  a  yellow  powder, 
heavier  than  water,  and  so  long  as  it  remains  dry,  aestitute  of  taste  and 
smell.  That  prepared  according  to  (1)  acquires  a  red  colour  and  loses 
the  property  of  combining  with  alkalis,  in  consequence  of  the  heat  re- 
quired to  drive  off  the  excess  of  phosphorus  mixed  with  it ;  it  likewise 
contains  a  somewhat  greater  quantity  of  oxygen.  To  obtain  pure  phos- 
phoric oxide  of  a  bright  red  colour,  and  not  capable  of  combining  with 
alkalis,  the  yellow  oxide  is  kept  for  1 0  hours  at  a  heat  of  300"".  (Leverrier.) 


2P  .... 

Calcnlatioii. 
62-8  

88-7  ... 

Leverrier  (5) 
88-64  

PdoUM   (1.) 

85-5 

O  ... 

8      

....  11-3  ... 

11-36  

14-5 

p«o  ... 

70-8  

....100-0  ... 

10000  

100-0 

rP^O  =:  4  .  196-14  +  100  =  784-56,  according  to  Berzeliiu.) 

DeeomposUums,  I.  The  oxide  heated  apart  from  the  air,  above  the 
boiling  point  of  mercury,  is  rapidly  decomposed  into  phosphorus  which 
evaporates,  and  phosphoric  acid  which  remains  behind.  (Pelouze, 
Leverrier.)  5P0  =  P0»+  9P.  2.  In  dry  air  it  may  be  heated  to  300^ 
without  decomposing,  and  begins  to  bum  at  the  temperature  at  which 
phosphorus  also  heated  apart  from  the  air  begins  to  volatilize.  (Leverrier.) 
3.  In  damp  air  it  oxidizes,  exhaling  a  faint  odour  like  that  of  phos- 
phuretted  hydrogen.  4.  It  rapidly  takes  fire  in  chlorine  gas  either  dry 
or  moist,  phosphoric  acid  and  chloride  of  phosphorus  being  produced. 
(Pelouze ;  Leverrier.)  5.  It  is  decomposed  by  sulphur,  the  decomposition 
commencing  at  the  melting  point  of  that  suh»6tance.  6.  In  contact  with 
aqueous  solutions  of  the  alkalis,  it  is  resolved  into  nearly  pure  phos- 
phuretted  hydrogen  gas,  and  a  phosphate  of  the  alkali.  If  the  quantity 
of  alkali  be  smidler  than  is  necessary  to  saturate  the  phosphoric  acid 
which  may  be  formed,  part  of  the  oxide  remains  undecomposed.  Baryta 
and  lime-water  decompose  the  oxide  more  slowly,  because  they  produce 
insoluble  phosphates  which  form  a  crust  round  the  oxide.  (Leverrier.) 
Hydrochloric  acid  gas  does  not  decompose  the  oxide,  even  with  the  aid 
of  heat.  (For  the  conversion  of  the  oxide  into  phosphoric  acid  by  oxi* 
dation,  vii  Formation  of  phosphoric  acid.) 

Combinations. — a.  With  water  : — Hydrate  of  phosphoric  oxide.  The 
preparation  of  this  compound  has  been  already  given  in  describing  that  of 
the  anhydrous  oxide  (5).  The  voluminous  yellow  mass  cannot  be  dried,  even 
at  ordinary  temperatures,  without  losing  its  combined  water  :  hence  the 
determination  of  its  composition  is  uncertain.  According  to  one  expe- 
riment, it  contains  79*5  (1  at.)  phosphoric  oxide  and  20-5  (2  at.)  water. 
It  reddens  litmus  feebly  even  after  being  washed  as  completely  as  pos- 
sible. It  suffers  scarcely  any  alteration  by  boiling  with  water ;  it  is 
only  after  48  hours'  boiling  that  the  hydrate  loses  a  portion  of  its  water, 
and  the  liquid  becomes  slightly  acid.  Exposed  to  the  rays  of  the  sun 
under  water,  it  is  converted  somewhat  rapidly  into  phosphoric  acid  and 
phosphuretted  hydrogen  gas.  It  is  very  slightly  soluble  in  water,  and 
imparts  to  that  liquid  the  property  of  blackening  copper- salts.  (Leverrier.) 

6.  With  phosphoric  acid. 


HYPOPHOSPHOROUS  ACID.  113 

c.  With  salifiable  Imses.  Phosphoric  oxide^  provided  it  has  not  been 
turned  red  by  the  application  of  a  strong  heat,  blackens  quickly  in  am- 
moniacal  gas  and  in  alkaline  solutions,  by  taking  up  the  alkali :  acids  turn 
it  yellow  again.  These  black  compounds  are  slightly  soluble  in  water, 
80  that  the  filtrate  blackens  copper-salts;  but  in  contact  with  water, 
they  are  quickly  decomposed  as  described  in  (6).  (Leverrier.^ 

Phosphoric  oxide  is  insoluble  in  alcohol,  ether,  yolatile  oils  and  fixed 
oils.  (Leverrier.) 

B.     HYPOPHOSPHOROUS  Acu).     PO. 

Acide  hypophospkoreua,  Acidum  hypopho^phorosum,  Unterphotphorige 

Saure. 

Formation,  1.  In  the  decomposition  of  phosphide  of  barium,  stron- 
tium, or  calcium,  by  water.  (Dulong.)  2.  When  phosphorus  is  gently 
heated  with  hydrate  of  lime,  or  boiled  with  milk  of  lime,  baryta-water, 
or  aqueous  or  alcoholic  solution  of  potassa.  (H.  Rose.)  When  aqueous 
solution  of  potassa  is  used,  a  large  quantity  of  phosphoric  acid  is  mixed 
with  the  hypophosphorous;  with  the  alcoholic  solution,  the  quantity  of 
phosphoric  acid  produced  is  but  small.     (H.  Rose.) 

Not  known  in  the  separate  state. 

Calculation.  H.  Rose,  Calc.        Dulong' 

P    31-4  79-695  7969    73-4 

O    8 20  305  20-31    26  6 

PO    39-4  100-000  100-00    lOO'O 

(P*0  =  2  .  196*14  + 100  =  492-28.    Benelius.) 

C<mbi7uxtum». — «•  With  water. — «.  HydraU  of  hypophoiphoroui 
<uid.  1.  Phosphide  of  barium  is  decomposed  by  water, — the  solution  of 
hypophosphite  of  baryta  thereby  formed  is  filtered  from  the  phosphate 
whicn  remains  nndissolved — ^the  baryta  precipitated  from  the  filtrate  by 
sulphuric  acid  added  in  due  proportion — and  the  liquid,  after  a  second 
filtration,  concentrated  to  the  consistence  of  a  syrup.  (Dulong.)  2. 
Phosphorus  is  boiled  with  baryta-water  till  it  disappears,  and  the  yapour 
no  longer  has  the  odour  of  garlic ;  the  baryta  is  precipitated  from  the 
filtrate  by  a  slight  excess  of  sulphuric  acid, — the  liquid  again  filtered — 
the  filtrate  agitated  in  the  cold,  and  for  a  short  time  only,  with  protoxide 
of  lead — ^the  sulphate  of  lead  removed  by  filtration — ^the  lead  precipitated 
from  the  liquid,  which  contains  basic  hypophosphite  of  lead,  by  nydro- 
sulphuric  acid  gas — and  the  filtrate  concentrated  by  evaporation.  When 
the  quantity  of  oxide  of  lead  is  too  small,  or  when  the  liquid  is  heated, 
some  of  the  oxide  is  reduced ;  when  the  liquid  is  sufiered  to  remain  too 
long  in  contact  with  it,  an  insoluble  basic  ^t  is  formed.  (H.  Rose.) 

The  hydrate  is  a  viscid,  nncrystallizable,  very  acid  liquid.  (Dulong.) 
W^hen  heated,  it  is  completely  decomposed,  together  with  the  water  of 
hydration,  the  products  being  the  less  inflammable  phoqphuretted  hydrogen 
gas,  and  phosphoric  acid  which  remains  behind.  (H.  Rose.)  2P0  + 
3H0  =  PH'  +  P0*.  The  statement  of  Dulong,  that  phosphorus  is  vo- 
latilized at  the  same  time,  is  contradicted  by  Rose. 

/?.  With  a  larger  quantity  of  water,  the  hydrate  forms  a  thin  colour- 
less solution  which  precipitates  the  metals  from  solutions  of  gold  and 
silver  (Dulong);  from  a  solution  of  corrosive  sublimate  it  precipitates 
calomel  or  metallic  mercury,  according  to  the  proportions  used.  (H.  Rose.) 

VOL.  II.  X 


I 


114  PHOSPHORUS. 

b.  With  salifiable  bases,  hjpophosphoroos  acid  forms  salts  called 
Hyp<ypho9phUe$, — Pi^eparaJbUm:  1.  By  dissolving  the  bases  in  the  aqaeoas 
solution  of  the  acid.  (Dalong.^  2.  aj  boiling  phosphoins  in  alooholic 
solution  of  potassa.  3.  B^  boiling  phosphorus  in  solution  of  baryta, 
strontia,  or  lime,  and  filtering  from  the  insoluble  phosphate  which  is 
formed  at  the  same  time.  4.  The  lime-salt  prepared  according  to  (2)  is 
precipitated  by  carbonate  or  sulphate  of  ammonia,  potassa,  or  soda — the 
iiquid  evaporated  to  dryness — and  the  hypophosphite  extracted  by  alcohol. 
5.  The  lime-salt  dissolved  in  water  is  boiled  with  an  insoluble  oxalate, 
as  that  of  magnesia  or  protoxide  of  manganese.  Many  other  oxalates 
decompose  hypophosphite  of  lime,  but  not  completely.  (H.  Rose.^ 

The  hypophosphites  are  mostly  crvstallizable :  they  cannot  exist  with- 
out a  certain  quantity  of  water,  whicn  amounts  to  1^  atoms  for  each  atom 
of  the  salt.  (H.  Rose.)  Hence,  for  example,  the  formula  of  the  baryta- 
salt  deprived  of  water  as  much  as  possible  is  :  2(BaO,  PO)  +  3Aq.  The  salts 
when  heated  are  converted — ^by  decomposition  of  the  water  which  essen- 
tially belougs  to  them — ^into  phosphuretted  hydrogen  gas,  generally  of  the 
easily  inflammable  kind,  and  a  di-phosphate  which  remains  behind. 
(Dulong;  H.  Rose.)  2BaO,2PO  H-  3H0  =  2BaO,6PO»  -h  PH».  Part  of 
the  phosphuretted  hydrogen  is  resolved  into  hydrogen  and  phosphorus, 
the  qaantity  thus  decomposed  increasing  with  the  heat,  being  greater 
therefore  when  the  salt  is  heated  strongly  and  suddenly,  than  when  it  is 
cautiously  heated,  and  greater  towards  the  end  of  the  operation,  when 
little  else  than  pure  hydrogen  is  evolved,  than  at  the  beginning.  Of  all 
these  salts,  the  lead  salt  yields  the  largest  Quantity  of  undecomposed 
phosphuretted  hydrogen.  The  cobalt  and  nickel  salts  when  heated  decom- 
pose a  somewhat  greater  quantity  of  water,  and  therefore  evolve  a  gaseous 
mixture  less  rich  in  phosphorus,  leaving  a  salt  which  contains  rather 
more  phosphoric  acid.  The  residue  which  remains  after  the  ignition  of 
the  hypophosphites  contains  a  certain  quantity  of  phosphoric  oxide,  which 
gives  it  a  red  colour  (white,  however,  at  the  temperature  of  ignition)  when 
the  phosphate  is  essentially  white,  and  black  when  the  phosphate  itself  is 
coloured.  (H.  Rose.) 

The  hypophosphites,  when  dry,  are  permanent  in  the  air;  but  in  the 
state  of  solution  they  oxidize  when  boiled  in  contact  with  the  air,  and  are 
converted  into  simple  phosphates.  KO,PO  -h  40  =  KO,PO*.  (Dnlong.) 
When  boiled  in  a  close  vessel,  they  remain  unaltered,  provided  no  excess 
of  alkali  is  present;  but  alkaline  hypophosphites  dissolved  in  water  and 
containing  excess  of  alkali,  are  decomposed  by  boiling  into  hydrogen  gas 
and  a  residual  alkaline  phosphate,  the  change  taking  place  with  greater 
rapidity  in  proportion  as  the  alkali  is  stronger,  its  quantity  greater,  and 
the  solution  more  highly  concentrated.  (H.  Rose.)  In  an  alcoholic 
solution,  the  resolution  of  the  hypophosphite  into  hydrogen  gas  and  an 
alkaline  phosphate  does  not  take  place  so  readily. 

3K0  +  PO  +  4H0  =  3K0,  P0»  +  4H. 

The  aqueous  solutions  of  these  salts  throw  down  metallic  copper  from 
solutions  of  copper  salts,  but  only  when  highly  concentrated,  and  at  a  high 
temperature.  When  mixed  with  hydrochloric  acid,  they  precipitate  calo- 
mel from  a  solution  of  proto-chloride  of  mercury  in  excess,  and  metallic 
mercury  when  the  mercurial  solution  is  not  in  excess.  With  nitrate  of 
silver  they  give  a  white  precipitate  which  soon  turns  brown  and  is  con- 
verted into  metallic  silver,  the  chan^  being  further  accelerated  by  the 
action  of  heat.     From  chloride  of  gold  they  precipitate  the  metal.  (H. 


PHOSPHOROUS  ACID.  115 

Roae,  Analyt.  Ghem.  1,  274.)  All  hypophosphites  are  soluble  in  water, 
sereral  also  in  alcohol;  some  of  them  deliquesce  in  the  air.  (Dnlong.) 
The  solution  does  not  precipitate  barjta,  strontia,  or  lime-water. 

^  All  the  hypophosphites  contain  at  least  2  atoms  of  water:  the 
hjdrated  acid  in  its  most  concentrated  form,  contains  three,  one  of  which 
is  basic  and  may  be  replaced  by  a  metallic  oxide ;  while  the  other  two 
are  in  a  state  of  more  intimate  combination,  and  cannot  be  replaced  by 
metallic  oxides,  but  appear  to  be  essential  to  the  constitution  of  the  acid, 
and  are  present  in  all  its  salts.  The  hydrate  may  therefore  be  denoted 
by  2H0,P0  H-  HO;  and  the  general  formula  of  a  hypophosphite  will  be 
(2H0,P0  +  RO  H-  nAq).  Hydrogen  as  well  as  oxygen  appears  then  to 
be  essential  to  the  constitution  of  the  acid.  For  this  reason,  Wurtz 
regards  it  as  a  compound  of  phosphorus,  hydrogen,  and  oxygen,  denoted 
by  the  formula  PH'O^.  On  this  hypothesis,  *  the  composition  of  the 
hydrate  will  be  HO,  PH*0',  and  the  general  formula  of  a  hypophosphite, 
RO,PH*0'  +  nAq.  In  the  compound  PH'O',  both  the  hydrogen  and 
oxygen  may  be  regarded  as  electro-negatiye  elements,  and  then  the  acid 
will  be  viewed  as  an  analogue  of  phosphoric  acid,  PO*,  in  which  2  atoms 
of  oxygen  are  replaced  by  2  atoms  of  hydro^n.  Or  again,  the  hydrogen 
and  phosphorus  may  be  regarded  as  positiye,  the  oxygen  as  negative, 
and  the  acid,  PH'O*,  as  a  compound  of  oxygen  with  the  compound  radical 
PHI  This  radical  has  actually  been  isolated  by  Paul  Th^naid.  (Vid, 
p.  133.)  IT 


C.    Phosphorous  Acid.    PO*. 

UnvoUkommene  Pho9phormure,  Photphorige  Siiure,  Aeide  photphareux, 
Acidum  photpharotum. 

FormcUum.  By  the  imperfect  combustion  of  phosphorus,  a.  When 
phosphorus  is  placed,  at  a  somewhat,  elevated  temperature,  in  contact  with 
a  small  quantity  of  air  sparingly  renewed  or  very  much  rarefied. 

h.  When  phosphorus  is  exposed  to  the  air  or  to  oxygen  gas  at  ordi- 
nary temperatures.  Slaw  comhugtion  of  phosphorus*  This  combustion  is 
attended  with  a  very  slight  degree  of  heat,  a  light  visible  only  in  the  dark, 
and  the  formation  of  white  fumes  which  smell  like  garlic.  The  phos- 
phorous acid  hereby  produced  condenses  with  the  moisture  of  the  air  to  a 
liquid,  and,  by  taking  up  an  additional  dose  of  oxygen,  is  converted  into 
a  mixture  of  phosphorous  and  phosphoric  acid. 

Phosphorus  exhibits  slow  combustion  in  the  air  when  it  is  exposed,  at 
ordinary  pressures,  to  a  temperature  above  7^  (44*6°  F.).  In  rarefied  air 
its  luminosity  increases  with  the  degree  of  rarefaction,  and  the  light  does 
not  diminish  in  brightness  even  in  the  vacuum  of  the  air-pump :  if  air  be 
then  suddenly  admitted,  the  light  disappears.  (J.  Davy.)  In  compreaed 
air,  phosphorus  does  not  shine  till  the  temperature  is  raised.  (Hell wig.} 
It  does  not  shine  in  air  compressed  to  four  atmospheres.  (J.  Davy.) 

In  oxygen  gas,  under  the  ordinary  atmospheric  pressure,  phoq>honis 
does  not  exhibit  slow  combustion  till  heated  to  27°  (80*6°  F.).  (It  behaved 
differently  in  oxygen  gas  prepared  from  chlorate  of  potassa  at  different 
times;  at  temperatures  between  16^  and  27°,  it  shone,  sometimes  not  at 
all,  sometimes  more  feebly  than  in  air,  sometimes  very  brightly,  in  flashes, 
a  degree  of  heat  being  likewise  produced  sufficient  to  melt  the  pbospho- 

I  2 


116  I>nOSPHORUS. 

Tua,  but  not  to  cause  rapid  inflamination.  (J.  Davy.)  At  a  temperature 
^t  which  it  does  not  shine^  it  volatilizes  unaltered  in  oxygen  gas,  and  then 
produces  luminosity  on  the  introduction  of  nitrogen  or  hydrogen  gas. 
When  nitrogen,  hydrogen,  carbonic  oxide,  carbonic  acid,  or  hydrochloric 
acid  2as  has  been  placed  in  contact  with  phosphorus  and  become  loaded 
with  its  vapour,  the  introduction  of  oxygen  gas  produces  an  emission  of 
light.  (Berthollet;  J.  Davy.)  In  oxygen  gas  under  a  pressure  of  1^ 
atmospheres,  phosphorus  does  not  shine  till  it  is  heated  to  its  melting 
point,  and  then  it  takes  fire  (J.  Davy) ;  on  the  other  hand,  it  shines 
at  ordinary  temperatures  in  oxygen  gas  rarefied  by  the  air-pump. 
(Schweigger;  J.  Davy.)  The  more  therefore  the  oxygen  is  rarefied, 
either  by  diminution  of  external  pressure  or  by  mixture  with  other  gases, 
nitrogen  for  example,  the  lower  is  the  temperature  at  which  the  phospho- 
rus begins  to  undergo  slow  combustion.  (Schweigger,  Sckw.  40,  16.)  It 
still  remains  to  be  explained  why  the  rarefaction  of  oxygen  gas  facilitates 
the  combustion. 

According  to  Th6nard,  the  slow  combustion  ceases  in  the  course  of  an 
hour  when  the  air  or  oxygen  gas  is  dry,  because  the  acid  formed  surrounds 
the  phosphorus  as  a  solid  crust,  and  thus  prevents  further  contact  between 
the  phosphorus  and  the  gas:  but  when  water  is  present,  it  is  rapidly 
attracted  by  the  acid,  which  then  deliquesces  and  allows  the  combustion 
to  go  on.  According  to  J.  Davy,  on  the  contrary,  phosphorus  bums  in 
air  thoroughly  dried  over  oil  of  vitriol  quite  as  rapidly  as  in  moist  air^ 
until  all  the  oxygen  is  consumed.  Accoinling  to  the  author*s  experiments, 
phosphorus  emits  no  fumes  in  air  dried  over  oil  of  vitriol,  but  still  shines 
very  feebly  in  the  dark. 

The  luminosity  of  phosphorus  in  the  air  is  not  prevented  by  the  pre- 
sence of  the  gas  or  vapour  of  sulphur,  hydrochloric  acid,  ammonia,  or 
acetic  acid.  (J.  Davy;  Graham.)  Phosphorus  shines  even  in  hydrochlo- 
ric or  carbonic  acid  gas  containing  but  a  trace  of  air.  On  the  other  hand, 
the  luminosity  is  prevented  by  phosphuretted  hydrogen,  sulphuretted 
hydrogen,  sulphurous  acid  gas,  vapour  of  sulphide  of  carbon,  vapour  of 
iodine,  (according  to  J.  Davy  this  last  vapour  stops  the  phosphorescence ; 
according  to  Graham,  it  does  not),  chlorine  gas,  nitrous  oxide  gas,  vapour 
of  hyponitric  acid,  marsh-gas,  defiant  gas,  or  the  vapour  of  ether,  alcohol, 
rock-oil,  oil  of  turpentine,  eupion,  creosote,  and  other  volatile  oils.  (J. 
Davy;  Graham;  Vogel.)  Many  but  not  all  of  these  substances  form 
compounds  with  phosphorus,  which  are  but  little  inclined  to  the  slow 
combustion. 

Phosphorus  does  not  shine  at  21^  in  air  which  contains  ^  J^^  of  its 
volume  of  phosphuretted  hydrogen  gas  not  spontaneously  inflammable. 
(Graham.)  At  10°,  less  than  -^ij  of  a  volume  of  sulphurous  acid  gas  is 
sufficient  to  prevent  the  luminosity  of  phosphorus  in  the  air,  but  at  IS"* 
it  shines  again  and  fuses.  (Vogel.)  [In  consequence  of  the  formation  of 
sulphide  of  phosphorus  ?]  Of  sulphide  of  carbon,  less  than  a  drop  is 
sufficient  to  prevent  the  luminosity  of  phosphorus  in  25  cubic  inches  of 
air  at  10°,  and  even  at  the  melting  point;  and  the  phosphorus  then  no 
longer  shines  in  a  fresh  portion  of  air,  unless  it  has  been  previously  washed 
and  dried  with  bibulous  paper.  (Vogel.) — J  of  a  volume  of  hydrosul- 
phuric  acid  gas,  or  -^  of  chlorine  added  to  1  volume  of  air  prevents  phos- 
phorus from  shining  in  it.  (Graham.)  Vapour  of  bromine  at  10"  merely 
weakens  the  luminosity  of  phosphorus  in  the  air,  but  does  not  completely 
destroy  it:  at  18",  phosphorus  fuses  in  air  charged  with  bromine,  but 
does  not  take  fire.    Of  chlorine  gas  at  least  8  measures  are  required  for 


PHOSPHOROUS  ACID.  11? 

every  100  measnres  of  air  at  12*5'*,  to  stop  the  phosphorescence.     When 
air  is  mixed  with  •}-  or  -^  of  its  volnme  of  chlorine  gas^  phosphorus  melts  in 
it  at  8^  in  consequence  of  the  formation  of  chloride  of  phosphorus,  and 
at  the  same  time  becomes  so  much  heated  that  it  takes  fire.  (Vogel.) 
In  a  mixture  of  air  and  nitrous  oxide  gas,  phosphorus  may  be  heated 
above  its  melting  point  without  emitting  light,  but  it  takes  fire  at  its 
boiling  point.     In  air  containing  a  trace  of  hyponitric  acid,  phosphorus 
does  not  shine.     Marsh-gas  retards  the  slow  combustion,  but  does  not 
altogether  prevent  it.  Even  -^-^  of  a  volume  of  defiant  gas  mixed  with  one 
volume  of  air  destroys  the  luminosity  at  a  temperature  of  15°  and  under  the 
ordinary  atmospheric  pressure  j    and  -j^,  even  at  21°.  In  a  mixture  of  air 
and  olefiant  gas,  phosphorus  may  even  be  heated  to  1 00°  without  taking  fire. 
When  the  external  pressure  is  diminished,  the  interfering  power  of  olefiant 
gas  becomes  less;  phosphorus  shines  at  21°  in  a  mixture  of  equal  volumes 
of  olefiant  gas  and  air  at  05  English  inches  external  pressure ;  of  1  volume 
of  olefiant  gas  with  2  volumes  of  air,  at  14  in. ;  wiUi  4  volumes  of  air,  at 
2*3  in.j  with  9  volumes  of  air,  at  2-2  in.;  with  19  volumes  of  air,  at  50  in. ; 
with   29  volumes,  at  10*3  in.;  with  39  volumes  , at  12-1  in.;  with  49 
volumes,  at  16*5  in.;  with  99  volumes,  at  25*5  in.;  with  199  volumes, at 
26'5  in.;  and  with  449  volumes  of  air,  at  29*0  in.  (Graham.)    Coal-gas  like- 
wise stops  the  phosphorescence  (Graham) ;  so  likewise  does  hydrogen  gas 
prepared  from  vapour  of  water  and  red-hot  iron  filings,  its  action  being 
due  to  vapour  of  oily  matters  mixed  with  it ;  for  that  prepared  hy  means 
of  harpsichord  wire  produces  no  such  effect.  (J.  Davy.)     In  air  impreg- 
nated with  vapour  of  alcohol,  phosphorus  does   not  shine  at   2 6 '7**. 
(Graham.)     Phosphorus  shines  at  19°  in  air  with  which  is  mixed  -j-f^  of 
its  volume  of  ether  vapour,  tbttt  ^^  vapour  of  sulphide  of  carbon,  or  xAt 
of  vapour  of  turpentine.    In  a  mixture  of  3  measures  of  air  and  2  measures 
of  ether  vapour,  phosphorus  emits  a  faint  li^ht  visible  only  in  the  dark, 
commencing  at  104*7°,  and  always  ceaising  when  the  temperature  falls  to 
99":  rapid  combustion  begins  at  115*5°.     In  a  mixture  of  111  volumes  of 
air  and  1  volume  of  vapour  of  rock-oil,  phosphorus  begins  to  shine  at 
67*7°;  and  in  a  mixture  of  116  volumes  of  air,  and  1  volume  of  vapour  of 
turpentine,  at  83*5^.     But  the  vapours  of  rock-oil  and  oil  of  turpentine 
rapidly  lose  their    interfering   power  when    the   external  pressure   is 
diminished.     The  oil  deposited  by  compressed  oil-gas  likewise  exerts  a 
preventive  action.  (Graham.)     Vapour  of  eupion,  and  still  more  that  of 
creosote,  mixed  in  small  quantity  with  air,  weakens  or  stops  the  emission 
of  light.  (Vogel.)     Camphor  vapour  mixed  with   air  produces  no  eflect, 
according  to  Graham,  but  according  to  J.  Davy,  it  stops  the  phosphores- 
cence. {Coinp.  Berthollet,  /.  Polytechn,  Cah,  3,  p.  275 ;  J.  Davy,  N,  Ed. 
FkU.  J.  15,  48;  also  Schw.  68,  384;  also  Ann,  Pharm,  9, 158;  Graham, 
y.  Quart.  J.  of  Sc,  6,  83;  also  Schw,  57,  230;  ahHr.  Pogg,  17,  375; 
Vogel,  Jun.  J.  pr.  Chem,  19,  394.) 

2.  By  dissolving  phosphorus  in  heated  nitric  acid.  Phosphoric  acid 
is  produced  at  the  same  time,  the  quantity  increasing  with  the  strength 
of  the  acid. 

3.  In  the  mutual  decomposition  of  water  and  terchloride  of  phospho- 
rus. {Sch.  40.) 

Preparation.  When  phosphorus  is  heated  to  100°  in  a  narrow  glass 
tube  containing  air  it  sublimes  as  phosphorous  acid,  a  small  quantity  of 
phosphoric  oxide  being  produced  at  the  same  time.  (Steinacher,  A.  GehL 
1,681.) — Berzelius  {Lehrb.  2,  67)  conducts  this  process  in  the  following 


118  PHOSPHORUS. 

manner.  One  end  of  a  glass  tnbe  10  inches  long  and  half  an  inch  wide, 
is  nearly  closed  at  one  end,  leaving  however  an  aperture  of  the  sise  of 
a  large  pin ;  it  is  then  bent  at  an  obtuse  angle  at  the  distance  of  from 
half  an  inch  to  an  inch  of  the  dosed  end;  a  piece  of  phosphorus  is  in- 
troduced and  placed  near  the  narrow  aperture  and  heated  from  time  to 
time:  it  then  bums  with  a  pale  greenish  flame,  and  forms  phosphorous 
acid,  which  condenses  in  the  part  of  the  tube  directed  upwards.  — 2.  Phos- 
phorus heated  in  highly  rarefied  air,  forms  phosphoric  acid,  phosphorous 
acid,  and  phosphoric  oxide.  (H,  Davj.) 

Properties.  Phosphorous  acid  forms  white  and  very  bulky  flakes, 
easily  volatilized  and  sublimed ;  smells  like  garlic ;  has  a  sour  and  cha- 
racteristically sharp  taste;  reddens  moistened  litmus  paper  strongly,  but 
not  that  which  is  dry.  (Steinacher.) 

Calcnlatioii.  Davy.        Beneliaa.       Dulong.     ThomBon. 

P    31-4  56-68  56  56524  5718  60 

30  24      43-32  44  43.476  4282  40 


P0» 55-4  10000  100  100000  10000  100 

(PtQ*  :»  2  .  196-14  +  3  .  100  =  69228.    BeneUiu.) 

Decompodtions.  1.  The  hydrated  acid  undergoes  decomposition  at  a 
certain  degree  of  concentration,  and  the  water  being  likewise  decomposed, 
the  products  are  phosphuretted  hydrogen  gas  of  the  less  inflammable 
variety,  and  hydrated  phosphoric  acid  which  remains  behind:  hence  the 
acid  when  heated  in  the  air  exhibits  vivid  combustion,  evolving  bubble 
of  gas  which  take  fire  as  they  escape.  (H.  Davy.) 

4P0»  +  9HO  =  6H0,  3P05  +  PH». 

2.  When  zinc  or  iron  is  dissolved  in  the  acid,  phosphuretted  hydrogen 
gas  and  a  salt  of  phosphoric  acid  are  likewise  produced.  (Berzelius). — 
3.  By  sulphurous  acid  {q.  v.). 

Combinations,  a.  With  water. — The  anhydrous  acid  attracts  the 
moisture  of  the  air  with  so  great  a  development  of  heat  that  it  takes  fire. 

«.  Hydrate  of  Phosphorous  Add,  Terchloride  of  phosphorus  is  de- 
composed by  water,  and  the  hydrochloric  acid  produced,  together  with  the 
excess  of  water,  driven  off  by  gentle  evaporation.  (H.  Davy.)  Instead 
of  preparing  the  chloride  of  phosphorus  beforehand,  it  is  better  to  fill  a 
cylinder  12  inches  long,  and  at  most  an  inch  in  diameter,  one-fourth  with 
phosphorus  and  three-fourths  with  water — ^heat  it  till  the  phosphorus 
melts — and  then  pass  chlorine  gas  washed  with  water  slowly  into  the 
liquid  through  a  tube  reaching  down  to  the  bottom  of  the  cylinder.  The 
chlorine  sets  fire  to  the  phosphorus,  combines  with  it,  and  forms  terchlo- 
ride of  phosphorus,  and  this  compound  is  decomposed  by  the  superin- 
cumbent water.  The  water  when  saturated  with  acid  must  be  replaced 
by  fresh  water,  and  more  phosphorus  added ;  for  when  the  quantity  of 
the  latter  is  too  small,  pentachloride  of  phosphorus  is  formed  and  con- 
verted into  phosphoric  acid.  (Droquet,  J,  Uhim.  Med.  4,  220,  abstr. 
Pogg.  12,  268.) 

After  being  concentrated  as  much  as  possible  in  a  retort  out  of  con- 
tact of  air,  or  in  vacuo  over  hydrate  of  potassa,  the  hydrate  remains  in 
the  form  of  a  thick  uncrystallizable  syrup  containing  74-26  acid  and 
27*54  water.  This,  when  gradually  heated,  is  resolved  into  71*62  per 
cent,  of  phosphoric  acid,  8-91  of  phosphuretted  hydrogen,  and  19*47  of 


PHOSPHOROUS  ACID.  119 

water;  but  when  rapidly  concentrated  and  to  a  greater  extent^  it 
yields  68*04  phosphoric  acid^  10*27  phosphuretted  hydrogen  and  21*69 
water. 

fi,  GrystaUixed  Fho^horous  Acid.  Formed  by  eyaporatinf  the  sola*' 
tion  to  a  thinner  syrup  than  that  above  mentioned^  and  cooling  it  ^H. 
Davy)— or  by  adding  a  small  quantity  of  water  to  the  hydrate.  (H. 
Rose.)  The  crystals  when  heated  yield  77  per  cent,  of  hydrate  of  phos- 
phoric acid  together  with  28  per  cent,  of  phosphuretted  hydrogen  and 
water.  (K.  I^avy*) 

y,  Aqueaiu  Pkogpkarous  Acid,  The  crystalliEed  acid  deliquesces  in 
the  air^  producing  a  colourless  liquid  which  exceeds  water  in  consistence 
and  specific  gravity :  this  liquid  when  concentrated  must  be  preserved  in 
close  vessels.  The  solution  precipitates  the  metals  from  chloride  of  gold, 
nitrate  of  silver,  and  protochloride  of  mercury,-— or  calomel  from  the 
latter,  when  the  mercurial  solution  is  in  excess. 

b.  With  various  salifiable  bases,  phosphorous  acid  forms  salts  called 
Phosphites  ;  but  with  many  metallic  oxides  it  is  incapable  of  combining, 
because  it  reduces  them.  The  affinity  of  phosphorous  acid  for  salifiabJe 
bases  is  but  small.  The  soluble  phosphites  have  a  somewhat  sharp 
taste,  like  garlic.  According  to  (traham,  the  normal  salts  contain  one 
atom  of  acid  to  three  atoms  of  base ;  but,  according  to  H.  Rose,  most  of 
the  phosphites  contain  one  atom  of  acid  to  two  atoms  of  base  j  and  others, 
one  atom  of  acid  to  one  atom  of  base.  It  appears  also  that  they  cannot 
be  obtained  in  the  anhydrous  state.  When  heated,  they  are  all,  together 
with  the  water  which  they  contain,  resolved  into  hydrogen  which  escapes 
as  gas,  and  a  phosphate  which  remains  behind;  hence,  when  heated  in  con- 
tact with  the  air,  they  bum  either  with  glow  or  with  flame.  Most  of 
the  phosphites  when  thus  decomposed  yield  pure  hydrogen  gas ;  e.  g. 

2BaO,  PCs  +  2HO  =  2BaO,  PO»  +  2H ; 
in  others,  a  small  quantity  of  phosphorus  is  mixed  with  the  hydrogen. 
The  phosphites  of  protoxide  of  manganese  and  oxide  of  lead,  which  when 
thoroughly  dried  do  not  contain  sufficient  water  to  efiect  this  decomposi- 
tion, are  resolved  into  a  mixture  of  much  hydrogen  with  a  small  quantity 
of  phosphuretted  hydrogen  gas,  and  a  compound  of  10  atoms  of  base  with 
4  atoms  of  phosphoric  acid. 

lOPbO,  6PO»  +  5H0  =  lOPbO,  4PO*  +  PH"  +  2H. 

Part  of  the  PH'  is  resolved  by  the  heat  into  its  elements;  hence  phos- 
phorus likewise  sublimes.  (H.  Rose.) 

At  ordinary  temperatures,  the  pnosphites  do  not  attract  oxygen  from 
the  air;  but  they  are  oxidized  and  converted  into  phosphates  by  nitric 
acid,  by  chlorine  water,  by  many  metaUic  oxides,  which  are  at  the  same 
time  reduced, — and  at  higher  temperatures,  by  salts  of  chloric  and  nitric 
acid  with  which  they  detonate.  (Vid.  Guy-Lussac,  Ann,  Chim.  Fhys. 
1,  212.)  They  are  not  altered  by  boiling  with  solution  of  caustic 
potassa, — ^neither  do  they  produce  any  evolution  of  hydrogen  gas.  They 
precipitate  the  metal  from  aqueous  solution  of  protochloride  of  copper,  but 
only  on  boiling.  (H.  Rose.)  From  solution  of  corrosive  sublimate  they 
precipitate  calomel,  and  from  nitrate  of  silver  and  chloride  of  gold  they 
throw  down  metallic  silver  and  metallic  gold — ^the  former  being  brown- 
black  when  precipitated  from  a  cold  solution,  and  black  when  precipitated 
at  a  boiling  temperature.  Many  simple  phosphites  are  insoluble  in  water, 
but  are  rendered  soluble  by  excess  of  acid.  Those  which  are  solu- 
ble in   water  precipitate  baryta  and  lime-water,  as  well  aa  the  salts 


120  PHOSPHORUS. 

of  the  earthy  alkalis,  the  earths,  and  the  heavy  metallic  oxides  (the 
lead -salts  most  easily  of  all), — sometimes  even  in  the  cold^  some- 
times, especially  when  the  solutions  are  very  dilute,  only  on  the  applica- 
tion of  heat.  They  do  not  precipitate  a  mixed  solutioii  of  sulphate  of 
magnesia,  sal-ammoniac,  and  ammonia,  when  diluted  to  a  certain  extent 
This  character  distinguishes  the  phosphites  from  the  phosphates.  (H. 
Rose.) 

IT  According  to  Wurtz,  the  phosphites  are  all  hihasic,  and  all  contain 
at  least  one  atom  of  water  (or  rather  of  the  elements  of  water).  The 
hydrogen  and  oxygen  thus  united  with  a  phosphite  are  never  evolved 
in  the  form  of  water  on  the  application  of  heat;  neither  can  they  he  re* 
placed  hy  an  atom  of  a  metallic  oxide.  The  crystallized  hydrate  of  phos- 
phorous acid  contains  3  atoms  of  water,  two  of  which  are  basic  and  may 
be  replaced  by  two  atoms  of  metallic  oxide;  but  the  third  is  inseparably 
bound  up  with  the  acid  and  is  essential  to  its  existence  as  an  acid. 
Hence  (as  in  the  case  of  hypophosphorons  acid)  phosphorous  acid  may  be 
regarded  as  a  compound  of  phosphorus,  hydrogen,  and  oxygen,  denoted 
by  the  formula  PHO^ — or  as  phosphoric  acid  in  which  one  atom  of  oxygen 
is  replaced  by  hydrogen.  According  to  this  view,  the  formula  of  tho 
crystallized  hydrate  will  be  2H0,  PHO^;  and  the  general  formuk  of  a 
phosphite: 

2RO,  PRO*  +  n  Aq. 
To  this  view  of  the  composition  of  anhydrous  phosphorous  acid,  it  may  be 
objected  that  the  compound  PO'  has  actually  ^en  isolated  (p.  117).  But 
the  properties  of  this  and  of  the  other  so-called  anhydrous  acids,  such  as 
SO',  SO',  PO',  &c.,  which  Gerhardt  calls  AnhydAdes,  are  altoffether 
different  from  those  of  the  corresponding  hydrated  compounds.  In  fact 
it  would  appear  that  the  presence  of  the  elements  of  water,  or  at  least  of 
hydrogen,  is  essential  to  the  development  of  acid  properties  properly  so 
called — and  that  tho  Anhydrides  are  not  really  acuU  m  the  true  sense  of 
the  word.  The  existence  of  PO'  in  the  separate  state  need  not,  there- 
fore, be  regarded  as  subversive  of  the  preceding  view  of  the  constitution 
of  phosphorous  acid.  (Wurtz,  Ann.  Pharm,  58,  49.)  If 

c.  With  alcohol  and  other  organic  liquids. 

Pelletiers  Phosphorous  acid,  ffypophosphoric  add,  Phosphalic  acid, — 
This  compound  is  obtained  by  the  slow  combustion  of  phosphorus.— > 
Pelletier's  method  of  preparing  it  {Orell,  Ann,  1796,  2,  447)  is  to  intro- 
duce a  number  of  separate  sticks  of  phosphorus  into  glass  tubes  an  inch 
long,  open  abo>eand  below,  but  drawn  out  funnel-shape  at  bottom — these 
tubes  being  arranged  in  a  funnel,  and  the  funnel  inserted  into  a  bottle 
which  stands  in  a  dish  containing  water.  The  whole  arrangement  is 
covered  with  a  glass  bell-jar,  but  in  such  a  manner  as  to  give  ac- 
cess to  the  external  air — which,  however,  ought  not  to  be  very  warm, 
as  in  that  case  the  phosphorus  would  melt  and  take  fire.  The  acid 
which  collects  in  the  bottle  is  equal  in  weight  to  three  times  the 
quantity  of  phosphorus  consumed,  but  it  may  be  obtained  in  a  more  con- 
centrated state  by  gentle  evaporation.  Bucholz  lays  the  sticks  of  phos- 
phorus on  the  upper  part  of  an  inclined  shallow  dish,  and  places  the  dish 
in  a  cellar  at  a  temperature  not  exceeding  50°  P.  The  acid  produced, 
which  amounts  to  more  than  five  times  the  weight  of  phosphorus  used, 
flows  down  into  the  lower  part  of  the  dish.  The  aqueous  acid  thus  ob- 
tained presents  the  character  of  a  dense  tenacious  syrup  of  faint  garlic 
odour  and  very  acid  taste;   it  evolves  phosphuretted  hydrogen  when 


PHOSPHORIC  ACID.  121 

heated,  and  combines  with  larger  quantities  of  water^  producing  considera- 
ble rise  of  temperature.  Phosphorus  containing  arsenic  yields  phos- 
phatic  acid  contaminated  with  arsenious  acid,  which  is  immediately  pre- 
cipitated by  sulphuretted  hydrogen :  the  acid  when  treated  with  zinc 
and  hydrochloric  acid,  evolves  arseniuretted  hydrogen,  and  when  heated 
alone  till  phosphuretted  hydrogen  is  evolved,  deposits  the  arsenic  in  black 
metallic  laminje.  (A.  Vogel,  J.  pr.  Chem.  13,  55.)  This  acid  of  Pelle- 
tier  may  be  re^rded  either  as  a  particular  degree  of  oxidation  of  phos-* 
phorus  occupying  an  intermediate  place  between  phosphorous  and  phos* 
phorlc  acid,  or  else  as  a  mere  mixture  of  those  two  acids. 


2P   ....   62-8  ... 
90  ....  72     ... 

.....  46-59  . 
53-41  . 

Th6iard. 

47  .... 

53  

Dulong. 
...  47-85 
...  52-15 

or 

PO»  ... 
4PO*  ... 

Calculation. 

.....  56-8  16-34 

....285-6  83-66 

P"0»   134-8     ... 

100-00  . 

100  

...10000 

p*o*» 

341-4  10000 

In  support  of  the  former  view  it  may  be  alleged  that,  according  to 
Dulong,  this  acid  always  contains  the  same  quantity  of  oxygen,  and  when 
exposed  to  the  air  even  for  a  considerable  time,  does  not  appear  to  be 
converted  into  phosphoric  acid  by  further  oxidation.  Since,  however, 
when  combined  with  salifiable  bases,  it  does  not  form  salts  of  a  peculiar 
kind^  but  merely  phosphites  and  phosphates,  the  latter  view  must  be  re* 
garded  as  the  more  probable.  The  phosphorous  acid  first  produced  by 
the  slow  combustion  of  phosphorus  appears  to  go  on  taking  up  more 
oxygen  till  four  atoms  of  phosphoric  acid  are  produced  for  each  atom  of 
phosphorous  acid  remaining.  Leverrier  (Ann.  Chim.  Phys.  Q5y  278), 
thinks  it  possible  that  phosphatic  acid  may  be  a  compound  of  phosphoric 
acid  and  phosphoric  oxide. 

D.    Phosphoric  Acid.    PO*. 

Acid  of  Bones,  AcicU  phosphorique,  Acidum  phosphorieum,  Phosphorsaure, 

Sources.  In  the  mineral  kingdom,  this  acid  occurs  in  combination 
with  lime,  magnesia,  protoxide  of  cerium,  yttria,  alumina,  and  the  oxides 
of  uranium,  manganese,  iron,  lead  and  copper;  in  various  rocks  of  igneous 
origin  (Fownes ;  Sullivan);  in  all  primitive  rocks  (R.  D.  Thomson);  in 
the  organic  kingdoms,  especially  in  the  animal,  combined  with  ammonia, 
potassa,  soda,  lime,  magnesia,  and  iron.  All  phosphates  in  the  mineral 
kingdom  contain  ordinary  phosphoric  acid,  (Boussingault,  Ann.  Chim. 
Phya.  55,  185.)  The  conclusion  that  they  cannot  therefore  have  been 
formed  at  a  high  temperature,  is  however  inadmissible  with  regard  to 
those  which  contain  one  atom  of  acid  to  3  atoms  of  base. 

Phosphorus  exhibits  rapid  combustion  under  the  following  circum- 
stances, the  surroundinff  medium  being  at  the  ordinary  temperature. 

».  When  considerable  quantities  of  air  are  presented  to  the  phosphorus 
— slow  combustion  taking  place  at  first  and  producing  a  slight  elevation 
of  temperature — this  rise  of  temperature  accelerating  the  slow  combustion 
— ^this  in  its  turn  raising  the  temperature  still  higher,  and  so  on — till  the 
phosphorus  attains  the  temperature  necessary  for  rapid  combustion^ 
According  to  Hiinefeld  (J.  pr.  Chem.  1,  233),  a  piece  of  phosphorus, 
loosely  wrapped  in  soft  white  blotting-paper  (which  perhaps  prevents 
the  cooling),  or  laid  with  the  freshly  cut  surface  in  contact  with  the 
paper — stakes  fire  in  a  few  minutes  at  a  temperature  of  20''  {5%"^  F.),  after 
previously  fusing  at  the  comers. 


122  PHOSPHORUS* 

0,  The  more  finely  the  phosphonis  is  diyided,  either  by  itself  or  by 
mixture  with  other  bodies  of  a  pulyemlent  nature— the  more  quickly 
therefore  the  gradual  oombnstion  can  go  on,  by  the  action  of  an  increased 
sarfiEU)e  of  contact — ^the  more  quickly  does  the  phosphorus  take  fire. 
Finely  granulated  phosphorus  rapidly  takes  fire  in  the  air  after  drying. 
Paper  saturated  with  solution  of  phosphorus  in  bisulphide  of  carbon,  takes 
fire  after  the  eraporation  of  the  latter^  because  the  phosphorus  remains 
on  the  paper  in  a  fine  state  of  division.  Many  of  the  preparations  known 
by  the  name  of  Phofphoru&^xes  are  also  formed  on  similar  principles. 
They  often  likewise  contain  substances  which  absorb  moisture  from  the 
air,  and  thereby  produce  a  rise  of  temperature  which  &yours  the  com- 
bustion. The  following  are  mixtures  of  this  kind :  Phosphorus  is  heated 
above  its  boiling  point  in  a  small  glass  flask,  and  air  is  several  times 
blown  in  with  the  blow-pipe,  while  the  contents  of  the  flask  are  constantly 
agitated.  In  this  manner  a  red  mixture  of  phosphorus,  phosphoric  oxide, 
phosphorous  acid  and  phosphoric  acid  is  produced.  These  acids,  by  their 
powerful  attraction  for  moisture,  favour  the  combustion  of  the  phosphorus. 
The  phosphoric  oxide  merely  exerts  a  mechanical  action,  serving  to  divide 
the  phosphorus.  Melting  phosphorus  mixed  with  phosphoric  oxide  like- 
wise, according  to  Pelouze  («/.  Ckim,  Med,  8,  533),  yields  a  luminous 
mixture.  Luminous  mixtures  are  likewise  obtained  by  heatin?  phos- 
phorus in  a  small  flask  together  with  calcined  magnesia  or  pounded  quick- 
lime till  it  melts,  the  materials  being  well  shaken  up  all  the  while. 
Saltzer  (Kastn.  Arch.  19,  120)  melts  in  a  small  flask  30  grains  of  phos- 
phorus with  10  grains  of  wax — blows  air  in  with  the  bellows  till  the 
phosphorus  takes  fire,  and,  in  consequence  of  the  higher  temperature  thus 
produced,  mixes  more  intimately  with  the  wax — and  then  closes  the  flask. 
Benedix  {Schw,  60,  129)  fuses  and  works  together,  1  part  of  fine  cork- 
powder,  1  part  of  bees-wax,  4  of  phosphorus,  and  8  of  rock-oil,  which 
must  be  free  from  turpentine.  The  mass  takes  fire  spontaneously  at  20°; 
at  lower  temperatures,  it  is  necessary  to  breathe  upon  it. 

y.  The  more  the  air  is  rarefied,  the  more  energetic  is  the  gradual  com- 
bustion, and  the  more  easUy  does  it  pass  into  rapid  combustion,  especially 
when  the  phosphorus  is  surrounded  with  floculent  substances  which 
prevent  its  cooling.  When  phosphorus  is  covered  with  cotton,  or  with 
pounded  resin  or  sulphur,  and  the  surrounding  air  rapidly  abstracted  by 
the  air-pump,  the  phosphorus  takes  fire  at  ordinary  temperatures.  (Van 
Marum,  Oren,  N.  J,  de  Fhys.  3,  96,  and  Van  Bemmelen,  A.  GehL  2,  252, 
N.  OM,  1,  144,  and  GiJb.  59,  268.  Meylink,  Repert.  46,  489.)  Accord- 
ing to  Bache  (Sill.  Am.  J.  18,  372;  also  Pogg.  23,  151;  also  Schw. 
63,  487)  there  is  no  necessity  for  surrounding  the  phosphorus  with  these 
different  powders,  in  order  to  cause  it  to  take  fire  on  rarefying  the  air : 
nevertheless  these 'powders  facilitate  the  inflammation — not  only  those  of 
sulphur  or  resin,  but  likewise  those  of  charcoal,  boracic  acid,  hydrate  of 
po^sa,  hydrate  of  baryta,  lime,  carbonate  of  lime,  magnesia,  sal-am- 
monia, common  salt,  chloride  of  calcium,  nitre,  fluor  spar,  silica,  arsenic, 
antimony,  manganese,  &e.  Animal  charcoal  and  lamp-black  act  so  power- 
fully (by  preventing  cooling)  that  phosphorus  sprinkled  with  them  takes 
fire  at  15*5®  (60°  P.)  even  in  the  open  air. 

On  the  other  hand,  the  inflammation  is  retarded  by  increase  of  external 
pressure.  When  phosphorus  is  heated  in  a  closed  retort  till  it  takes  flre, 
the  increased  pressure  produced  by  the  heat  causes  the  extinction  of  the 
flame;  on  opening  the  retort,  the  flame  again  appears.  (J.  Davy.) 


PHOSPHORIC  ACID.  123 

FormcUion.     1 .  From  phosphornB.     a.  Phosphoric  acid  is  prodaced 
in  the  rapid  combnetion  of  phoephoruB,  provided  a  sufficient  quantity 


phosphoric  acid^  which  partly  rises  in  a  white  cloud  luminous  in  the  dark, 
partly  remains  in  a  glassy  condition  mixed  with  phosphoric  oxide,  at  the 
place  where  the  phosphorus  bums.  According  to  Davy,  phosphorous  acid 
is  often  produced  at  the  same  time. 

6.  Phosphorus  is  converted  into  phosphoric  acid  by  abstracting  oxygen 
from  the  following  substances.  From  carbonic  acid  combined  with  a 
fixed  alkali,  the  action  being  attended  with  moderate  inflammation  (a 
piece  of  phosphorus  is  placed  at  the  closed  end  of  a  glass  tube,  and  a  fixed 
alkaline  carbonate  in  the  middle;  the  latter  is  heat^to  redness,  and  then 
the  phosphorus  converted  into  vapour  by  the  application  of  heat) ;  from 
concentrated  sulphuric  acid,  hypochlorous  and  chlorous  acid,  nitrous  oxide, 
nitric  oxide,  hyponitric  and  nitric  acid,  also  from  the  salts  of  iodic,  hyper- 
iodic,  hromic,  chloric,  hyperchloric,  and  nitric  acid,  and  from  most  metallic 
oxides  and  metallic  acids, — the  products  of  the  decomposition  being  a 
phosphide  of  the  metal  and  a  phosphate  of  the  oxide. 

2.  From  phosphoric  oxide.  This  substance  oxidizes  slowly  in  moist 
air,  takes  fire  when  heated  to  300^  (572°  F.),  and  is  converted  into 
phosphoric  acid  by  oil  of  vitriol,  nitric  acid,  chlorate  or  nitrate  of  potassa, 
oxide  of  copper,  and  the  salts  of  sesqui-oxide  of  iron,  oxide  of  copper,  and 
oxide  of  silver.  (Pelouse ;  Leverrier.) 

3.  From  hypophosphorous  acid,  which  is  converted  into  phosphoric 
acid  both  by  heating  (p.  113),  and  by  contact  with  aqueous  solution  of 
iodine  or  chlorine,  with  hypochlorous  or  nitric  acid,  and  with  oxide  of 
notercury,  gold,  or  silver. 

4.  From  phosphorous  acid.  By  burning  the  anhydrous  or  the  concen- 
trated acid  in  the  air  (p.  118);  by  continued  exposure  of  the  dilute  acid 
to  the  air;  by  oil  of  vitriol,  chlorine,  hypochlorous  acid^  nitric  acid,  and 
by  salts  of  mercury,  silver,  and  gold. 

FreparcUion.-^The  only  method  of  obtaining  phosphoric  acid  in  the 
anhydrous  state  is  by  the  rapid  combustion  of  phosphorus  in  dry  air  or 
oxygen  gas. 

1.  A  few  grains  of  phosphorus  are  set  on  fire  in  a  porcelain  cap- 
sule standing  on  a  dish,  and  covered  with  an  inverted  bell-jar  of  the 
capacity  of  200  or  300  cubic  inches :  the  fiakes  of  acid  produced  are 
deposited  on  the  sides  of  the  jar  and  on  the  dish.  By  renewing  the 
air,  fresh  quantities  of  phosphorus  may  be  burnt.  (Berzelius,  Lehrh, 
2,  59.) 

2.  A  glass  globe  with  three  apertures,  two  at  the  sides  and  one  at  the 
top,  is  connected  by  one  of  the  lateral  apertures  with  a  wide  glass  tube 
filled  with  chloride  of  calcium  and  open  to  the  air  at  the  other  end ;  into 
the  other  horizontal  aperture  is  fitted  a  bent  glass  tube  which  passes  into 
one  of  the  mouths  of  a  Woulfe*s  bottle.  From  the  other  mouth  of  this 
bottle  a  tin  tube  proceeds  vertically  upwards,  and  is  surrounded  by  a 
wider  tin  tube  perforated  with  holes,  so  that  it  may  be  heated  by  means  of 
red-hot  charcoal  placed  in  the  outer  tube.  The  heat  thus  applied  pro- 
duces a  continuous  draught  of  air  through  the  chloride  of  calcium  tube 
into  the  globe,  and  thence  through  the  Woulfe's  bottle  into  the  tin  tube. 
Lastly,  to  the  third  opening  of  the  globe  situated  at  the  top  is  adapted  a 


124  PHOSPHORUS. 

porcelain  tube ;  and  from  the  lower  extremity  of  this  is  saspeuded  a  small 
dish,  in  which  the  phosphorus,  thrown  in  from  time  to  time  by  the  upper 
end  of  the  tube  (which  can  be  closed  by  a  stopper)  is  to  be  burnt.  When 
a  sufficient  quantity  of  phosphorus  has  been  consumed,  the  three  tubes 
are  removed  from  tne  apertures  of  the  globe,  the  apertures  closed,  the  acid 
shaken  loose  from  the  sides,  and  quickly  introduced  into  a  dry,  well 
stopped  glass  vessel.  (Delalande,  Ann,  (fkim.  Fhys,  76,  117>  also  J.  pr. 
Chem,  23,  300.) 

3.  A  porcelain  crucible  is  placed  on  a  large  dish  of  the  same  material^ 
and  on  the  crucible  is  laid  a  small  porcelain  capsule  containing  some  pieces 
of  phosphorus:  a  large  tubuhited  bell-jar  is  placed  over  the  whole. 
Through  the  cork  which  closes  the  opening  there  passes  a  narrow  bent 
tube,  and  likewise  a  wide  straight  tube  which  descends  into  the  interior 
of  the  jar.  The  bent  tube  serves  to  introduce  a  supply  of  oxygen  gas 
evolved  from  chlorate  of  potassa,  or  contained  in  a  gas-holder,  and  pre- 
viously dried  by  chloride  of  calcium.  Through  the  straight  tube  a  red-hot 
wire  is  passed  for  the  purpose  of  setting  nre  to  the  phosphorus;  and, 
when  the  first  portion  is  burnt  away,  fresh  pieces  are  dropped  in  to  sup- 
ply its  place.  If  the  glass  globe  becomes  too  hot,  the  process  is  inter- 
rupted for  a  time.  The  floculent  acid,  which  weighs  more  than  twice  as 
much  as  the  phosphorus  used,  is  scraped  together  with  a  spoon  and  put 
into  a  bottle.  (Marchand,  J.  pr.  Cliem.  16,  373.) 

4.  Phosphorus  is  placed  upon  a  porcelain  dish  and  covered  with  a 
funnel  having  a  hole  in  its  side,  through  which  the  phosphorus  can  be 
set  on  fire,  and  fresh  pieces  introduced.  The  funnel  is  connected  by  a 
bent  tube  with  a  Woulfe's  bottle  containing  water,  and  communicating 
by  means  of  a  second  tube  with  an  aspirator  (p.  35),  by  which  a  draught 
of  air  is  kept  up.  The  acid,  which  is  mixed  with  phosphorous  acid, 
accumulates  under  the  funnel  and  in  the  bent  tube.  (Brunner,  Fogg. 
38,  267.) 

Properties,  The  acid  which  sublimes  during  the  combustion  presents 
the  aspect  of  white  flakes ;  that  which  remains  where  the  phosphorus  is 
burnt,  forms  a  vitreous  mass.  It  fuses  at  a  red  heat,  and,  according  to 
Davy  {Ann,  Chim,  Fhys.  10,  218),  sublimes  below  a  white  heat,  ft  is 
inodorous ;  not  corrosive ;  of  strong  and  agreeable  sour  taste;  and  reddens 
litmus  strongly.  With  baryta,  strontia,  or  lime-water,  it  produces  white 
flakes  which  dissolve  in  an  excess  of  the  acid. 

Valentiiie 
Calcolalion.  Lavoisier.  Thomson.  H.Davy.  Berzelias.    Dolong.     Rose. 

P 31-4  ....  43*98  ....  39-35  ....  4286  ....  426  ....  43-936  ....  44*923  ....  46-5 

50 40     ....  56-02  ....  60*65  ....  5714  ....  57*4  ....  56064  ....  55077 ....  53*5 

P0» 71*4  ....100*00  ....100*00  ....100*00  ....100*0  ....100*000  ....100-000....100-0 

(P*0*  =  2  .  196*14  +  5  .  100  =  892*28.    Benelias.) 

Phosphoric  acid  is  decomposed  by  charcoal  at  a  red  heat,  with  forma* 
tion  of  carbonic  oxide;  by  potassium,  sodium  (by  these  with  inflamma- 
tion), zinc,  iron,  and  some  other  metals,  the  products  being  a  metallic 
phosphide  and  an  oxide  of  the  metal  or  phosphate  of  the  oxide. 

Combinations,  Phosphoric  acid  occurs  in  three  isomeric  (or  poly- 
meric 1)  states  (I.,  109;  II.,  16),  as  Metaphosphoric  or  a-Phosphonc  acid  = 
aVO\  one  atom  of  which  takes  up  only  one  atom  of  base ;  as  Pyrophos- 
phoric  or  ^-Phosphoric  acid  =  6P0*,  which  combines  with  2  atoms  of  base; 


PHOSPHORIC  ACID.  125 

and  OS  ordinary  or  e-Phosphoric  ==  cPO^  which  requires  3  atoms  of  hase. 
The  acid  obtained  by  the  rapid  combustion  of  phosphorus  is  the  meta-* 
Dhosphoric;  the  other  two  varieties  are  not  known  in  the  separate  state, 
but  only  in  combination  with  water  or  with  bases.  The  particular  state 
in  which  the  acid  may  exist  depends  upon  the  quantity  of  water  or  base 
with  which  it  is  united.  If  no  base  or  water  is  present,  or  if  the  acid  is 
combined  with  only  one  atom  of  it,  the  variety  produced  is  the  metaphos- 
phoricacidj  this,  when  2  atoms  of  base  are  present,  especially  at  high 
temperatures,  is  converted  into  pyrophosphoric-^and  with  8  or  more  atoms 
of  base,  into  ordinary  phosphoric  acid.  Conversely,  the  last  two  varie* 
ties,  by  abstraction  oi  water  or  base,  are  converted  into  the  first. 

These  diversities  may  be  explained  on  the  hypothesis  either  of  iso- 
merism, or  of  polymerism.  (I.,  109.)  The  atoms  of  oxygen  and  phos- 
phorus appear  to  dispose  themselves  in  different  ways  according  to  the 
number  of  atoms  of  water  or  of  base  presented  to  them,  and  thus  to  form 
acids  of  various  degrees  of  saturating  power.  According  to  Graham's 
view  (Ann.  Pharm,  28,  19),  on  the  other  hand,  there  is  but  one  kind 
of  phosphoric  acid.  When  this  acid  is  intimately  combined  with  only  one 
atom  of  water,  it  can  likewise  take  up  by  substitution  (I.  37)  only  one 
atom  of  base;  whereas,  when  intimately  combined  with  2  or  3  atoms  of 
water,  it  can  take  up  2  or  3  atoms  of  base  in  their  stead.  But  why  does 
the  anhydrous  acid,  when  dissolved  in  a  large  quantity  of  water,  unite 
intimately  with  but  one  atom  of  that  substance,  and  not  with  two  or  three, 
unless  it  exists  in  a  peculiar  condition  ? 

a.  Combinations  with  water. 

Hydrate  of  Metaphosphoric  Acid,  Glacial  Phoapkoric  Acid,  The 
aqueous  solution  of  either  of  the  three  acids  is  evaporated  in  a  platinum 
crucible  till  the  quantity  of  water  in  the  residue  no  longer  diminishes. 
With  the  last  portions  of  water,  a  quantity  of  acid  likewise  volatilizes. 
The  syrupy  liquid  solidifies,  on  cooling,  to  a  transparent  glass  which  vola- 
tilizes altogether  at  a  red  heat. 


Calcalatiou. 

H.  Rose. 

Pdigot. 

Dubng. 

BerthoUet 
(nearly) 

75 

25 

flPO* 71-4  ....   88-81  .... 

HO 9-0  ....    1119  .... 

....  92-7  ....  90-52  ... 
....     7-3  ....    9-48  ... 

87-45  .. 

12-55  .. 

82-92 

17-08 

HO,aPO*....80-4  ....^lOOOO  1000  ....10000  100-00  100-00  100 

The  diversities  in  the  amount  of  water  found  in  these  several  analyses 
are  to  be  attributed  to  the  different  degrees  to  which  the  evaporation  was 
carried.  Berthollet's  hydrate  appears  to  have  been  that  of  pyrophos- 
phoric  acid.  Peligot  had  heated  his  hydrate  to  redness.  Rose's  analyses 
show  that,  after  rapid  evaporation,  there  remains  a  mixture  of  hydrated 
and  anhydrous  acid. 

Solution  of  Metaphotphoric  Acid,  The  anhydrous  acid  obtained  by 
combustion  rapidly  deliquesces  in  the  air.  It  dissolves  in  water  with 
disengagement  of  heat;  but  the  flakes  do  not  dissolve  entirely  in  less 
than  an  hour.  The  hydrate  deliquesces  in  the  air.  According  to  Berzelius, 
when  water  is  poured  upon  this  substance,  it  splits  with  violence  into 
small  pieces,  which  are  projected  upwards:  solution  takes  place  but 
slowly.  The  same  solution  is  obtained  when  metaphosphate  of  soda  dis- 
solved in  water  is  precipitated  by  acetate  of  lead,  the  metaphosphate  of 
lead  diffused  through  water  and  decomposed  by  sulphuretted  hydrogen, 
and  the  liquid  filtered.  ^Graham.)  This  solution  ^ves  white  precipi- 
tates with  cnloride  of  banum  or  calcium,  nitrate  of  silver,  aud  solution  of 


126  PHOSPHORUS. 

white  of  egg  :  it  likewise^  a<3Cording  to  Graham,  throws  down  a  difficultly 
soluble  Bait  from  solution  of  potassa.  One  part  of  anhydrous  phosphoric 
acid  dissolyed  in  10,000  parts  of  water  reddens  litmus,  and  gives  an  imme- 
diate precipitate  with  lime-water  or  acetate  of  lead ;  with  one  part  of  acid 
in  20,000  parts  of  water,  the  precipitate  does  not  appear  for  half  an  hour. 
(Harting,  J,  pr,  Chem.  22,  48.)  After  standing  for  several  days,  and 
more  quickly  when  boiled,  the  solution  (according  to  Graham)  loses  these 
properties,  and  is  converted  at  once  into  ordinary  phosphoric  acid,  not 
first  into  pyrophosphoric  acid ;  because  the  water  acting  in  excess  induces 
the  acid  to  assume  the  state  in  which  it  is  capable  of  taking  up  the  largest 
quantity  of  water  (3  atoms). 

Hydrate  of  Pyrcphotphoric  add.  By  evaporating  a  solution  of  ordinary 
phosphoric  acid  in  a  platinum  flask  till  the  temperature  rises  to  213*^(415^ 
F.),  an  acid  is  obtained  containing  23  per  cent.  (2-^  at.)  of  water.  (  Vid. 
aeq.  Graham.)  In  this  state  it  may  take  the  form  of  a  soft  glass. — Peligot 
obtained  it  in  opaque,  indistinct  crystals  like  loaf-sugar.  Fused  phos- 
phoric acid  was  left  to  itself  in  a  bottle  for  several  years,  and,  by  absorb- 
ing water,  formed  at  the  top  transparent  crystals  of  ordinary  phosphoric 
acid,  in  the  middle  a  mother  liquid  of  1*7  sp.  gr.,  and  at  the  bottom 
crystals  of  hydrated  pyrophosphoric  acid  like  those  above  mentioned. 
{Ann.  Chim.  Fhys.  73,  286;  also  J.  pr.  Chem.  21,  169.) 


*P0*  .... 

Calculation. 
71*4  

79-87  

PeKgot. 
76-97 

2HO    

18      , 

20-13  

2303 

2H0,  *PO*  . 

89-4  

10000  

100-00 

The  crystals  examined  were  still  mixed  with  a  portion  of  the  hydrate 
of  ordinary  phosphoric  acid.  (Peligot.) 

JSolution  of  Pyrophosphoric  acid.  Pyrophosphate  of  soda  dissolved 
in  water  is  precipitated  by  acetate  of  lead;  the  precipitated  pyrophos- 
phate of  lead  is  washed,  diffused  through  water,  and  decomposed  by 
hydrosulphuric  acid,  and  the  solution  filtered  from  sulphide  of  lead. 
This  solution  gives  a  white,  earthy  precipitate  with  nitrate  of  silver,  but 
does  not  precipitate  chloride  of  barium  or  calcium,  or  solution  of  white  of 
egg.  The  aqueous  solution  of  this  acid,  even  when  dilute,  remains 
unaltered  for  naif  a  year,  according  to  Graham  ;  but  when  heated,  it  is 
converted  into  ordinary  phosphoric  acid. 

Hydrate  of  ordinary  Phosphoric  add;  CrystaUized  Phosphoric  acid. 
Aqueous  solution  of  ordinary  phosphoric  acid,  evaporated  to  a  thin  syrup 
and  left  at  rest,  crystallizes,  according  to  Siiersen  {Scher,  J.  8,  125), 
Steinacher  {A.  Gehl.  1,  577),  and  Stromeyer  (Grund.  d.  iheor.  Chem.  1, 
248),  in  right,  four-sided  prisms,  slightly  inclined,  or  in  broadly  flattened 
six-sided  prisms,  terminated  with  quadrilateral  summits,  and  having 
planes  of  cleavage  parallel  to  the  lateral  faces  of  the  rhombic  prism. 
The  crystals  are  perfectly  transparent,  hard,  and  brittle. 


cPO»  .... 

Calculation. 
71*4  

,..  72-56  

Brandes. 
72-205  

Peligot. 
71-6 

3HO   .... 

27-0  

...  27-44  

27-795  .    . 

28-4 

3H0,cP0*    98-4  100-00  lOOOOO  1000 

At  149°,  the  acid  does  not  lose  any  water;  at  160**  it  parts  with  its 
water  very  slowly.  Evaporated  in  a  platinum  vessel  to  213^  till  it  loses 
scarcely  any  more  water,  it  still  retains  23'02  per  cent,  (about  2 J  at.), 
and  is  for  the  most  part  converted  into  pyrophosphoric  acid;  for  when 


PHOSPHORIC  ACID.  127 

dissolved  in  water  and  mixed  with  soda,  it  yields  abundance  of  crystals 
of  pyrophosphate  of  soda^  and  but  few  of  the  ordinary  phosphate.  A 
snuJl  quantity  of  metaphosphoric  aoid  is  also  formed  eyen  before  the 
quantity  of  water  has  been  reduced,  b^  increase  of  heat,  below  21-91  per 
cent.  (2  at.^j  the  quantity  of  this  acid  formed  becomes  considerable,  if 
by  raising  the  temperature  abore  the  melting-point  of  lead,  the  quantity 
of  water  is  reduced  below  18*7  per  ceut«  ^Graham.)  When  phosphoric 
acid  is  ignited  in  an  open  crucible,  a  considerable  quantity  of  the  acid 
volatilizes  with  the  water;  in  a  covered  crucible  this  does  not  take  place. 
After  gentle  ignition,  the  acid  forms,  on  cooling,  a  soft  glass  containing 
about  20  per  cent,  of  water;   after  stronger  ignition,  it  forms  a  hard 

flass  (metaphosphoric  acid  containing  1 0  per  cent,  of  water).  (Berzelius, 
fehrb.  2,  64.)     In  an  open  platinum  dish,  pure  hydrate  of  phosphoric 
acid  may  be  completely  evaporated.  (H.  Rose.) 

SoliUion  of  ordinary  Phosphoric  acid. — Preparation.  1.  Prom  Phos- 
phorus, a.  Considerable  quantities  of  phosphorus  are  burnt  by  degrees 
under  a  glass  bell-jar,  according  to  the  method  of  Berzelius  and  Brunner 
(p.  123);  the  phosphoric  acid  washed  together  with  water;  the  solution 
mixed  with  nitric  acid  and  evaporated,  in  order  to  convert  phosphoric 
oxide  and  phosphorous  acid  into  phosphoric  acid;  and  the  excess  of 
nitric  acid  removed  by  further  evaporation.  Or,  according  to  Funke, 
phosphorus  is  burnt  on  a  spoon  in  an  oil  of  vitriol  bottle  containing  a 
small  quantity  of  water  and  nitric  acid,  and  the  solution  evaporated. 
Leube  {J.  pr,  Chem.  2,  276)  decomposes  the  nitric  acid  by  boiling  with 
charcoal,  till  nitric  oxide  gas  is  no  longer  evolved ;  by  this  process,  how- 
ever, a  quantity  of  artificial  tannin  may  be  introduced  into  the  acid. 
The  acid  produced  by  the  combustion  is  the  metaphosphoric;  but  this 
when  boiled  is  converted  into  the  ordinary  acid. 

b.  Phosphorus  is  converted  by  slow  combustion  (p.  120)  into  phos- 
phatio  acid;  this  is  mixed  boiling  with  nitric  acid,  as  long  as  nitric 
oxide  gas  is  evolved,  and  the  excess  of  acid  removed  by  evaporation. 
(Bncholz,  Beitr.  zur  Erweiterung  d,  Ghent.  1,  69.) 

c.  Phosphorus  is  heated  with  dilute  nitric  acid,  by  which  it  is  dis- 
solved, with  evolution  of  nitric  oxide  gas,  partly  as  phosphorous,  partly  as 
phosphoric  acid;  the  liquid  is  evaporated — ^whereupon,  at  a  certain 
degree  of  concentration,  the  nitric  acid  still  present  converts  the  phos- 
phorous acid  into  phosphoric;  more  nitric  is  then  added,  till  the  evolution 
of  nitric  oxide  gas  ceases ;  and  the  evaporation  is  continued  till  all  the 
undecomposed  nitric  acid  is  driven  off. 

The  solution  of  the  phosphorus  in  nitric  acid  is  performed  in  a  glass 
flask,  or  better  in  a  retort,  in  order  that  the  nitric  and  hyponitric  acids, 
which  carry  phosphorus  over  with  them  (according  to  Wittstock,  because 
phosphuretted  hydrogen  is  evolved),  may  be  collected  in  a  receiver  and 
poured  back  again.  The  solution  is  evaporated  in  basins  of  porcelain 
(the  glazing  of  which  is  less  easily  attacked  by  the  concentrated  acid 
than  glass)  or  of  platinum.  In  concentrated  nitric  acid,  phosphorus 
often  takes  fire;  consequently,  when  strong  acid  is  used,  the  phosphorus 
must  be  introduced  in  separate  pieces,  each  being  left  to  dissolve  before 
another  is  put  in.  On  this  account,  an  acid  of  specific  gravity  1-1  or  1*2 
is  to  be  preferred ;  the  phosphorus  may  then  be  put  in  all  at  once  without 
danger;  if  the  effervescence  should  become  too  violent,  the  fire  must  be 
removed.  One  part  of  phosphorus  requires  about  13  parts  of  nitric  acid 
of  specific  gravity  1*2,  to  dissolve  it.  (Wittstock.)  The  conversion  of 
the  phosphorous  acid  into  phosphoric  acid,  and  the  effervescence  attending 


128  PHOSPHORUS. 

it,  take  place  when  the  quantity  of  liquid  is  reduced  to  about  eight  times 
that  of  the  phosphorus  used.  (Wittstock.)  As  soon  as  the  effervescence 
begins,  the  liquid  turns  yellow  (from  the  presence  of  h jponitric  acid  ?). 
(Sohbnbein.)  When  the  effervescence  stops,  nitric  acid  is  added  in  small 
portions  at  a  time,  the  heating  being  still  continued  as  long  as  any 
effervescence  is  produced.  Lastly,  when  the  liquid  is  so  far  evaporated 
that  its  temperature  rises  to  188°  (370°  F.),  in  which  case  it  weighs 
about  four  times  as  much  as  the  original  quantity  of  phosphorus,  the 
whole  of  the  nitric  acid  is  expelled.  (Wittstock.)  It  by  very  great 
concentration,  &P0^  or  aPO'  should  be  produced,  these  acids  may  be 
reconverted  into  cPO'  by  subsequent  solution  in  water,  and  boiling*.  If 
the  phosphorus  contains  arsenic,  this  metal  dissolves  at  first  in  the  nitric 
acid,  in  the  form  of  arsenious  acid.  This  acid  remains  dissolved  during 
the  evaporation,  provided  there  is  sufficient  nitric  acid  present  to  oxidate 
the  phosphorous  acid.  But  if  this  is  not  the  case,  and  the  remaining 
phosphorous  acid  evolves  phosphuretted  hydrogen  gas,  the  arsenic  is 
thereby  reduced  in  the  form  of  a  black  powder,  which,  on  the  addition 
of  nitric  acid,  is  re-dissolved  with  evolution  of  nitric  oxide  gas.  The 
arsenic  may  therefore  be  removed  by  diluting  and  filtering  the  liquid 
from  which  it  has  separated,  boiling  down  again,  and  treating  the  residue 
several  times  with  phosphatic  acid,  till  no  more  black  powder  separates. 
(Liebig.)  Since,  however,  in  this  process,  a  great  deal  of  phosphorus  is 
lost  in  the  form  of  phosphuretted  hydrogen,  Wittstock  thmks  it  prefer- 
able to  dissolve  the  phosphoric  acid  in  water,  after  it  has  been  completely 
oxidized  bjr  nitric  acid,  and  freed  from  the  excess  of  that  acid  by  strong 
concentration — ^then  saturate  it  with  hydrosulphnric  acid,  and  leave  it  to 
stand  for  some  time.  The  excess  of  nitric  acid,  however,  converts  the 
arsenious  into  arsenic  acid,  which  is  but  slowly  precipitated  by  hydrosul- 
phnric acid.  The  liquid  must  therefore  be  saturated  with  hy<m>sulphuric 
acid,  placed  for  some  days  in  a  stoppered  bottle,  and  if  it  then  no  longer 
smells  of  hydrosulphnric  acid,  again  saturated,  and  put  aside,  &c. — till, 
even  after  several  days,  no  more  sulphide  of  arsenic  is  precipitated,  and 
the  liquid  retains  the  odour  of  hydrosulphnric  acid;  it  is  then  to  be 
filtered,  and  freed  by  evaporation  irom  hydrosulphnric  acid.  Warming 
the  liquid  while  impregnated  with  hydrosulphnric  acid,  accelerates  the 
precipitation,  but,  according  to  Barwald,  induces  the  formation  of  hypo- 
sulphuric  acid  (1).  The  acid  thus  prepared  is  free  from  ammonia. 
(L.  A.  Buchner. — Comp.  Martins  8c  Kastner,  Reperi,  15,  73;  Barwald, 
Berl  Jakrb,  33,  2,  113;  Wittstock,  Berl.  Jahrh.  33,  2,  125;  Liebig,  Ann, 
Fharm.  11,  260;  Schbnbein,  J.  pr.  Chem,  16,  121;  L.  A.  Buchner, 
BepeH.  66,  215;  Gieseler,  N.  Br.  Arch,  19,  313;  Reinsch,  J.  pi\  Chem. 
28,  235.) 

2.  Frcm  Bone-ash.  The  bones  of  oxen  burnt  to  whiteness  contain, 
according  to  Berzelius,  in  100  parts,  86  phosphate  of  lime,  6  carbonate 
of  lime,  5  fluoride  of  calcium,  and  3  phosphate  of  magnesia;  other  kinds 
of  bone-ash  are  similarly  composed. — (a.)  100  parts  of  bone*ash  are  digested 
with  about  06  parts  of  oil  of  vitriol  diluted  with  from  10  to  16  times  its 

*  ReiiiBch  Hub  observed  that  phoBphorns  is  but  slightly  attacked  by  nitric  add  in 
an  open  vessel,  and  at  comparatively  low  temperatures,  because  it  becomes  covered 
with  a  film  of  oxide.  When  the  air  is  excluded  and  the  temperature  kept  low,  pure 
nitric  oxide  is  evolved  aud  phosphoric  add  formed,  the  liquid  acquiring  a  blue  colour. 
At  a  boiling  heat  and  out  of  contact  of  air,  nitric  add  acts  upon  phosphorus  in  sudi  a 
manner  that  nearly  all  the  oxygen  of  the  liberated  nitric  oxide  is  transferred  to  the 
phosphorus,  and  nitrogen  gas  is  evolved.  If  the  air  has  access  to  the  liquid,  the  nitric 
oxide  is  not  decomposed  (/.  pr.  Chem.  28,  385  -,  Ann.  Pharm.  48,  205).     [W.] 


PHOSPHORIC  ACID.  129 

weight  of  water;  the  phosphoric  acid  is  strained  tlirough  linen;  the 
sulphate  of  lime  remaining  on  the  filter  washed  with  water;  and  the 
liquid  thus  obtained  is  concentrated  by  evaporation,  freed  bj  filtration 
through  linen  from  the  sulphate  of  lime  which  separates  from  it,  and 
further  purified  in  various  ways. 

The  oil  of  vitriol  must  be  free  from  arsenious  acid ;  otherwise  this 
acid  will  be  transferred  to  the  phosphoric  acid.  The  digestion  of  the 
bone-ash  with  the  dilute  sulphuric  acid,  which  is  performed  with  frequent 
stirring  in  vessels  of  porcelain,  stoneware,  or  lead,  must  be  continued  for 
a  day  or  more,  the  liquid  being  ultimately  raised  to  the  boiling  point. 
Burnt  bones  in  the  solid  state  may  also  be  used :  the  decomposition  is 
complete  when  they  are  reduced  to  a  paste.  When  the  quantity  of 
sulphuric  acid  is  too  small,  phosphate  of  lime  remains  dissolved  in  the 
phosphoric  acid :  in  this  case,  a  further  addition  of  sulphuric  acid  to  the 
concentrated  liquid  precipitates  sulphate  of  lime,  which  is  almost  inso- 
luble in  the  liquid  supersaturated  with  sulphuric  acid.  The  excess  of 
sulphuric  acid  may  be  removed  by  further  evaporation ;  but  sulphate  of 
magnesiar— which,  on  the  application  of  a  stronger  heat,  parts  with  its 
sulphuric  acid  and  is  converted  into  phosphate — and  a  smidl  quantity  of 
sesqui-oxide  of  iron,  still  remain  mixed  with  the  phosphoric  acid.  When 
100  parts  of  bone-ash  are  digested  in  90  parts  of  oil  of  vitriol,  a  portion 
of  the  phosphate  of  lime  remains  undecomposed :  when  equal  weights  are 
used,  a  small  quantity  of  sulphuric  acid  remains  in  excess.  (Funcke, 
N'.  Tr.  8,  2,  3.)  Liebig  {Ann.  Pharm.  9,  255;  11,  260)  employs  equal 
parts  of  bone-ash  and  oil  of  vitriol — separates  the  phosphoric  acid  from 
the  gypsum— concentrates  it  considerably — adds  oil  of  vitriol  to  it  when 
cool,  as. long  as  sulphate  of  lime  separates — strains  the  liquid  through 
linen,  after  diluting  it  with  water— evaporates  again— once  more  adds 
oil  of  vitriol  as  long  as  any  precipitate  is  produced — and  lastly,  frees  the 
filtrate  from  excess  of  sulphuric  acid,  by  evaporating  till  the  heat  rises  to 
redness.  The  residue  is  free  from  lime  and  sulphuric  acid,  but  still  con- 
tains magnesia,  which  can  only  be  removed  by  solution  in  alcohol  or 
by  precipitation  with  carbonate  of  ammonia. 

To  purify  phosphoric  acid  obtained  from  bone-ash  by  the  action  of 
sulphuric  acid,  as  completely  as  possible  from  lime  or  magnesia,  alcohol 
or  ammonia  may  be  used.  Purification  hy  alcohol :  The  acid  evaporated 
to  a  syrupy  consistence  is  agitated  with  excess  of  alcohol  and  filtered 
from  the  insoluble  matter,  which  consists  of  lime  and  magnesia  combined 
with  phosphoric  or  sulphuric  acid  (any  arsenious  acid  which  may  happen 
to  be  present  remains  dissolved,  Wackenroder),  The  alcohol  is  recovered 
by  distillation.  In  this  process,  small  quantities  of  sulphovinic  and  phos- 
phovinic  acids  are  formed  (Biichner,  Liebig,  jinn.  Pharm,  9,  254),  in  con- 
sequence of  which,  the  acid  becomes  yellow  on  further  evaporation,  and 
evolves  olefiant  gas.  By  igniting  the  acid  these  compounds  are  de- 
stroyed, the  decomposition  being  attended  with  a  blackening  of  the  acid, 
which  may  be  removed  by  nitric  or  sulphuric  acid.  Commercial  phos- 
phoric acid  obtained  from  bones  may  also  be  dissolved  in  alcohol  with 
addition  of  sulphuric  acid;  or  again,  the  digested  mixture  of  bone-ash 
and  sulphuric  acid  may  be  at  once  exhausted  with  alcohol.  {Vid. 
TrommsdorflT,  N.  Tr.  1,  1,  51 ;  2,  1,  354;  Trommsdorfi",  junr.,  N.  Br. 
Arch.  11,  229.) 

Purification  hy  Ammonia.  The  liquid  obtained  by  the  decomposition 
of  bone-ash  by  dilute  sulphuric  acid  is  saturated,  after  filtration,  with 
carbonate  of  ammonia,  which  precipitates  triphosphate  of  lime  and  am- 

VOL.    II.  K 


130  PHOSPHORUS. 

monio-pliosphaie  of  magnesia;  the  complete  separation  of  the  precipitate 
is  facilitated  bj  warming  the  liqnid.  The  phosphate  of  ammonia  obtained 
by  evaporation  of  the  filtrate  is  freed  from  ammonia  by  continued  fusion 
at  a  red  heat  in  a  porcelain  or  platinum  crucible.  Tne  residue  is  the 
hydrate  of  metaphosphorio  acid,  and  must  be  reconverted  into  ordinary 
phosphoric  acid  by  solution  in  water  and  boiling.  But  according  to  Du- 
long  (ifi^.  (FAreu€il,  S,  444)  and  Balard  (Ann,  Ckim.  Phys.  57,  278), 
the  whole  of  the  ammonia  is  not  expelled  by  a  red  heat,  even  when  long 
continued;  and  at  a  white  heat,  phosphide  of  platinum  is  formed.  More- 
over, when  porcelain  crucibles  are  used,  their  glazing  is  strongly  attacked 
by  the  acid,  which  thence  becomes  contaminated  with  alkali  and  earthy 
matters;  and  if  crucibles  of  platinum  are  employed,  the  utmost  care 
must  be  taken  to  ensure  the  absence  of  carbon,  and  consequently  of  all 
organic  matters;  since  otherwise  phosphorus  will  be  reduced  and  will 
combine  with  the  platinum,  forming  an  easily  fusible  phosphide  of  the 
metal,  and  consequently  the  crucible  will  be  perforated. 

IT  Gregory^ z  Method  of  Purification.  The  solution  of  phosphoric  acid 
from  which  the  lime  has  been  separated  by  excess  of  sulphuric  acid 
(Liebig's  method),  is  evaporated  to  a  syrup  and  gently  ignited,  to  drive 
off  the  sulphuric  acid.  The  glass  thus  obtained  is  dissolved  in  boiling 
water,  and  the  solution,  which  is  perfectly  clear,  concentrated  by  evapor- 
ation and  maintained  for  a  quarter  or  half  an  hour  at  a  temperature  of 
about  315°  C.  (600^  F.),  at  which  the  phosphoric  acid  begins  to  evaporate 
with  the  water.  A  white  powder  then  separates  in  considerable  quantity, 
consisting,  according  to  Gregory's  analysis,  of  phosphoric  acid  and  mag- 
nesia, in  the  proportion  of  3  atoms  of  acid  to  2  of  bfuse.  The  syrupy 
mass  is  left  to  cool,  afterwards  digested  in  cold  water,  and  the  liouid 
filtered.  The  filtrate  is  a  solution  of  pure  phosphoric  acid.  This  method 
is  much  more  advantageous  than  either  of  the  preceding :  for  the  glacial 
acid  purified  by  alcohol  still  retains  a  considerable  quantity  of  magnesia ; 
and  the  mode  of  purification  by  ammonia  is  objectionable,  on  account  of 
the  difficulty  of  expelling  the  last  traces  of  ammonia,  and  the  great  chance 
of  injury  to  the  platinum  vessels.  (Gregory,  Ann.  Phann.  54,  94.) 
Maddrell,  however,  finds  that  the  acid  obtained  by  Gregory's  process  is 
not  absolutely  pure,  but  retains  traces  of  magnesia  and  soda.  The  pre- 
sence of  soda  in  phosphoric  acid  obtained  from  bones  appears  to  have 
been  previously  overlooked ;  it  is  of  course  derived  from  the  bones  them- 
selves. Maddrell  finds  that  the  white  precipitate  above  mentioned,  which 
Gregory  supposed  to  be  an  anomalous  phosphate  of  magnesia,  contains 
about  8  per  cent,  of  soda,  and  is  in  fact  a  double  metaphosphate  of  soda 
and  magnesia:  3(MgO,PO«)  +  NaO,PO«.  {Ann.  Pharm.  61,  53.) 
From  these  considerations  it  would  appear  that  phosphoric  acid  quite  free 
from  the  impurities  above  mentioned,  can  only  be  obtained  either  by 
dissolving  phosphorus  in  nitric  acid,  or  else  by  the  method  of  Berzelius 
next  to  be  described.  But  the  acid  obtained  by  Gregory's  process  appears 
to  be  sufficiently  pure  for  nearly  all  purposes.  IT 

h.  Bone-ash  is  dissolved  in  the  smallest  possible  quantity  of  nitric 
acid — ^the  solution  mixed,  while  still  hot,  with  acetate  of  lead — and 
the  precipitated  phosphate  of  lead  digested  jfbr  some  hours  with  the  liquid, 
which  possibly  contains  more  or  less  acetate  of  lead  in  excess,  in  order  to 
decompose  the  small  quantity  of  phosphate  of  lime  mechanically  carried 
down  with  the  precipitate.  The  phosphate  of  lead  is  then  thoroughly 
washed  on  the  filter  with  hot  water,  and  afterwards  dried  and  ignited,  to 
destroy  any  organic  matter  which  may  be  present.     Finally,  100  parts  of 


PHOSPHORIC  ACID.  131 

the  phosphate  of  lead  thus  obtained  are  decomposed  by  digestion  with 
33-25  parts  of  oil  of  vitriol  and  400  of  water— the  liquid  is  filtered  and 
evaporated — the  sulphuric  acid  driven  oflf  by  ignition  in  a  platinum 
crucible — the  residue  dissolved  in  water — and  the  oxide  of  lead  precipi- 
tated by  hydrosulphuric  acid  gas.  ^Berzelius,  Lehrh.  2,  61.) 

Impurities  in  Fhosphorio  add, — Fhofpkorous    acid:    Precipitates 
calomel  from  a  solution  of  corrosive  sublimate;   produces  a  blackish^ 
instead  of  a  yellowish  white  precipitate  with  snbnitrate  of  mercury;  pre- 
cipitates sulphur  when  heated  with  sulphurous  acid ;  and  evolves  phos- 
phuretted  hydrogen  gas  when  heated  with  dilute  sulphuric  acid  in  Marsh's 
apparatus  (vide  Arsenic). — Metaphosphoric  acid :    Gives  with  nitrate  of 
baryta  or  nitrate  of  silver  a  white  precipitate  soluble  in  nitric  acid.— 
Sulphuric  acid:  Gives  with  salts  of  oaryta  a  white  precipitate  insoluble 
in  hydrochloric  acid. — Nitric  add:  Decolorizes  solution  of  indigo  when 
heated  with  it;  evolves  nitric  oxide  gas  when  heated  with  copper  or 
mercury;  yields  nitrate  of  lime  when  supersaturated  with  lime,  filtered, 
and  evaporated.     [When  the  solution  is  mixed  in  a  test-tube  with  sul- 
phuric acid,  and  a  solution  of  protosulphate  of  iron  carefully  poured  upon 
it,  a  brownish-black  ring  is  produced  at  the  surface  of  separation  of  the 
two  liquids.  (W.)] — Ammonia:  Evolved  on  supersaturating  the  liquid 
with  lime  or  potassa. — Lim>e:    Precipitated  by  ammonia;  xf,  however, 
metaphosphoric  acid  be  present,  the  mixture  remains  clear,  because  meta- 
phosphate  of  lime  is  soluble  in  metaphosphate  of  ammonia,  but  becomes 
opalescent  after  some  da^s,  in  proportion  as  cPO'  is  formed  (Liebig); 
oxalic  acid,  however,  precipitates  the  lime  from  the  mixture. — Magnesia: 
Precipitated  by  ammonia,  especially  on  the  application  of  heat. — Arseni- 
ous  acid:  Immediate  yellow  precipitate  by  hydrosulphuric  acid. — Arsenic 
add:  The  liquid  saturated  with  hydrosulphuric  acid  and  kept  in  a  stop- 
pered bottle,  deposits  a  yellow  precipitate  after  a  day  or  more ;  if  the 
liquid  has  been   boiled  with  sulphurous  acid,  the .  precipitate  appears 
immediately.     The  presence  of  arsenic  us  or  arsenic  acid  may  also  be 
shown  by  Marsh's  apparatus. — Sesgui^xide  of  iron:    Reddens  sulpho- 
cyanide  of  potassium.— C^xtc^  of  lead^  or  oxide  of  copper:  Precipitated 
black-brown  by  hydrosulphuric  acid,  after  proper  dilution  of  the  liquid. 
(The  statement  of  Runzler  (Br.  Arch.  3,  208),  that  lead  is  not  pre- 
cipitated from  phosphoric  acid  by  hydrosulphuric  acid,  is  without  founda- 
tion.) 

The  aqueous  solution  of  phosphoric  acid  is  of  a  syrupy  consistence 
when  concentrated.  According  to  Dalton,  100  parts  of  this  solution,  of 
specific  gravity  1*85,  contain  .50  parts  of  acid;  at  1*6  sp.  gr.,  40  parts; 
at  1*39  sp.  ffr.,  30  ^ts;  at  1-23  sp.  gr.,  20  parts;  and  at  )-l  sp.  gr.,  10 
parts  of  acid.  It  gives  a  white  precipitate  with  baryta,  stroutia^  or  Ihna- 
water,  and  with  solution  of  acetate  of  lead;  does  not  precipitate  chloride 
of  barium  or  strontium,  or  white  of  egg;  and  gives  with  nitrate  of  silyet, 
on  the  addition  of  a  small  quantity  of  ammonia^  a  precipitate  of  a  bright 
yellow  colour. 

6.  Combinations  with  Salifiable  Bases :  Pko^)hatesin  general.  The 
affinity  of  phosphoric  acid  for  bases  is  greater  than  that  of  carboni<^ 
boracic,  hypophosphorous,  or  phosphorous  acid,  and  it  neutralizes  the 
bases  more  completely.  Phosphates  are  fixed  in  the  fire,  provided  the. 
base  be  so,  and  for  the  most  part,  easily  fuse  to  a  vitreous  mass.  ^  Char- 
coal appears  not  to  decompose  the  compounds  of  phosphoric  acid^  witli 
the  fixed  alkalis^  eren  at  a  strong  red  beat,  excepting  whea  silica  ia 

K   S 


132  t>HOSP}IOtttS. 

{>resent.  (It.,  104.)  Of  the  remaining  salts  of  phosphoric  acLd^  some 
are  resolved  by  charcoal  into  metallic  oxide  and  free  phosphorus 
(magnesia);  some  into  metal  and  free  phosphorus  (oxide  of  lead); 
others  are  converted  into  metallic  phosphides,  part  of  the  phosphorus, 
however,  being  at  the  same  time  set  free.  If  a  salt  of  phosphoric  acid  be 
fused  with  boracic  acid  on  charcoal  before  the  blowpipe,  and  when  the 
glass  has  been  brought  to  a  state  of  tranquil  fusion,  a  small  piece  of  fine 
harpsichord  wire  be  put  into  it,  and  the  inner  flame  directed  upon  it  with 
a  strong  blast,  a  fused  globule  of  brittle  magnetic  phosphide  of  iron  will  be 
formed.  If  the  base  of  the  salt  is  such  as  would  exert  a  disturbing 
action,  the  salt  may  be  dissolved  in  hydrochloric  acid,  the  solution 
saturated  when  cold  with  hydrated  sesqui-oxide  of  iron,  the  filtrate 
heated  to  the  boiling  point,  and  the  basic  phosphate  of  iron  thereby 
precipitated,  treated  as  above  with  boracic  acid  and  harpsichord  wire. 
(Berzelius.) 

Phosphates  heated  with  potassium  yield  phosphide  of  potassium.  If, 
therefore,  a  phosphate  be  heated  with  potassium  in  a  glass  tube,  and,  when 
the  mass  has  cooled,  the  excess  of  potassium  be  removed  by  mercury,  and 
moist  air  blown  in,  or  if  the  residue  be  moistened  with  water — ^phos- 
phuretted  hydrogen  gas,  easily  detected  by  its  odour,  is  evolved.  (Th^nard; 
Vauquelin.) 

All  phosphates  are  decomposed  by  sulphuric  acid.  A  platinum  wire 
moistened  with  oil  of  vitriol,  then  dipped  in  the  finely-pounded  salt,  and 
heated  in  the  blowpipe  flame,  imparts  to  it  a  green  colour  easily  recog- 
niasable  in  the  dark.  rFuchs,  Erdmann,  Schw.,  24,  180;  59,  26.) 

The  compounds  of  phosphoric  acid  with  potassa,  soda,  and  lithia  are 
soluble  in  water,  in  whatever  proportions  the  base  and  acid  may  be 
united.  The  remaining  phosphates  are  nearly  insoluble  in  water  except- 
ing when  they  contain  an  excess  of  phosphoric  acid.  They  are  likewise 
all  soluble  in  dilute  nitric  acid.  The  solutions  give  with  nitrate  'or 
acetate  of  lead  a  white  pulverulent  precipitate  of  phosphate  of  lead.  This 
precipitate,  when  heated  upon^charcoal  in  the  outer  blowpipe  flame,  fuses  to 
a  globule  which,  on  cooling,  solidifies  to  an  angular  mass;  with  borax  it 
forms  a  glass  which  is  transparent  while  hot,  but  becomes  opaque 
and  white  upon  cooling;  when  very  strongly  i^ited  upon  charcoal,  it 
evoWes  phosphorus;  difi'used  through  water  and  decomposed  by  hydro- 
sulphuric  acid,  it  yields  a  filtrate  containing  phosphoric  acid.  Of  the 
insoluble  phosphates,  some  do  not  ^ive  up  any  of  their  acid  to  fused 
hydrate  of  potassas  or  boiling  solution  of  potassa  {e.  g,  triphosphate  of 
lime);  others  give  up  nearly  all,  {e,  g,  the  phosphates  of  magnesia,  protoxide 
of  cerium,  sesqui-oxide  of  chromium,  protoxide  of  manganese,  sesqui-oxide 
of  iron,  and  protoxide  of  nickel). 

Metaphosphates.  These  salts  are  produced  when  aqueous  metaphos- 
phoric  acid  is  brought  in  contact  with  a  base,  or  when  one  atom  of 
pyrophosphoric,  or  of  ordinary  phosphoric  acid  is  ignited  with  one 
atom  of  base.  They  always  contain  one  atom  of  base  and  one  atom 
of  acid;  e,  g,  NaO,  aPO*.  The  soluble  salts  have  a  slight  acid  re- 
action; they  precipitate  chloride  of  barium  in  gelatinous  flakes,  and 
the  salts  of  many  earths  and  heavy  metallic  oxides  in  the  form  of 
liquid  hydrates;  these  precipitates  likewise  become  more  or  less  fluid 
on  boiling  the  liquid.  When  the  solution  is  very  dilute,  only  a  slimy 
precipitation  is  produced.  The  metaphosphates  give  a  white  precipi- 
tate with  nitrate  of  silver.  That  obtained  with  baryta  is  converted, 
by  boiling  for  several  hoars,  into  dBaO,  cPO^  (Graham.) 


PHOSPHORIC  ACID.  133 

IT  ModifiecUions  of  Metapkosphoric  acid.  The  meiaphosphates  just 
spoken  of,  are  those  which  are  formed  by  doable  decomposition  from  the 
vitreous  metaphosphate  of  soda,  obtained  by  quickly  cooling  the  salt  from 
a  state  of  fusion.  They  are  wholly  destitute  of  crystalline  structure,  and 
it  is  difficult  to  obtain  them  in  a  definite  form.  The  vitreous  metaphos- 
phate of  soda  may,  however,  be  brought  into  the  crystalline  state  by  very 
slow  cooling.  If  a  considerable  quantity  of  the  vitreous  salt  be  fused  in 
a  platinum  crucible  enclosed  within  one  or  more  earthen  crucibles,  and 
left  to  cool  very  slowly,  the  mass  when  solidified  is  found  to  have  acquired 
a  beautiful  crystalline  structure;  and  on  digesting  this  crystalline  mass 
in  warm  water,  not  using  a  very  large  excess,  the  liquid  divides  into  two 
strata,  the  one  which  is  the  larger  in  quantity  containing  the  crystallized 
inetaphosphate,  and  the  other  the  common  vitreous  salt.  When  the 
solution  of  the  crystallized  salt  is  mixed  with  solutions  of  various  metallio 
oxides,  e.  g,  nitrate  of  silver,  acetate  of  lead,  chloride  of  barium,  ^c, 
crystalline  salts  of  the  various  bases  are  obtained,  containing  water  of 
crystallization :  e.  g,  3(AgO,  PO*)  4-  2H0;  PbO,  PO*  +  HO,  &c.  (Fleitmann 
&  Henneberg,  Ann.  Pharm,  68,  304.)  By  adding  dilute  phosphoric  acid  in 
excess  to  solutions  of  various  metallio  salts,  evaporating  to  expel  excess. of 
acid,  and  heating  to  upwards  of  316°  C.  (600°  F.),  metaphosphates  of  the 
various  bases  are  produced  in  the  form  of  earthy  powders,  which  are  all, 
even  the  potassa  and  soda  salts,  insoluble  or  nearly  so  in  water.  (Mad- 
drell,  Mem.  Ckem.  Soc.  S,  373.)  It  appears  then  that  metaphosphoric 
acid — at  least  in  combination  with  salifiable  bases — is  susceptible  of 
three  distinct  modifications.  These  are  attributed  by  Messrs.  Fleitmann 
&  Henneberg  to  polymeric  conditions:  thus,  the  three  classes  of  salts 
may  perhaps  be  represented  by  MO,  P0»;  2MO,2PO';  3MO,3PO*;  or 
possibly  by  MO,  PO*;  3MO,3PO*j  6MO,6PO».  IT 

Pyrophosphates.  These  salts  are  formed  when  aqueous  pyrophos- 
phoric  acid  is  brought  in  contact  with  a  salifiable  base,  or  when  one  atom 
of  metaphosphoric  or  ordinary  phosphoric  acid  is  ignited  with  two  atoms 
of  base.  They  contain  either  2  atoms  of  base  to  1  atom  of  acid,  e,  g. 
2NaO,  6P0* :  Norrnal  or  Di-pyrophosphates ;  or  1  atom  of  base  and  I 
atom  of  water  to  1  atom  of  acid,  e.  g.  NaO,  HO,  6P0' :  Acid  or  Simple 
Pyrophosphates.  The  soluble  normal  salts  have  a  slight  alkaline  reaction. 
Both  the  normal  and  the  acid  soluble  salts  give  white  precipitates  with 
chloride  of  barium  and  nitrate  of  silver,  the  latter  precipitate  forming  a 
chalky  powder.  When  a  quantity  of  dipyrophosphate  of  soda  (2NaO, 
5P0^)  containing  1  part  of  phosphoric  acid  is  dissolved  in  10,000  parts 
of  water,  the  solution  produces  a  strong  turbidity  in  baryta  or  lime-water, 
and  in  solutions  of  nitrate  of  baryta,  chloride  of  calcium,  and  nitrate  of 
silver ;  with  20,000  parts  of  water,  the  turbidity  is  faint ;  with  40,000 
parts  very  faint,  not  appearing  for  half-an-hour  in  lime-solutions ;  with 
80,000  parts  of  water,  the  lime-solutions  give  no  turbidity,  and  the  other 
three,  only  a  very  faint  cloudiness;  and  with  160,000  parts  of  water,  the 
same  solutions  produce  nothing  more  than  a  faint  opalescence.  (Las- 
saigne,  J.  Chim.  Med.  8,  523.) 

Ordinary  Phosphates.  These  are  produced  on  bringing  ordinary 
phosphoric  acid  in  contact  with  a  base,  and  on  igniting  one  atom  of 
metaphosphoric  or  pyrophosphoric  acid  with  3  or  more  atoms  of  base. 
For  1  atom  of  acid  they  contain,  either  3  atoms  of  base :  Normal  or 
Tri-phosphates,  otherwise  called  Basic,  e.  g.  3NaO,cPO';  or  2  atoms  of 
base  and  1  atom  of  basic  water :  Di-phcsphates,  otherwise  called  NeiUral, 
e.  g.  2NaO,  HO,  cPO',  the  ordinary  phosphate  of  soda;  or  1  atom  of  base 


1S4  PHOSPHORUS. 

and  S  fttoiDB  of  batio  water :  Simple  PhoBphates,  otberwise  called  Aeidy  e,  g, 
NaO,  2H0,  cPO*.  The  bibasio  salts  sometimefl  contain  two  different 
baflee  with  one  atom  of  water,  «.  g.  NH*0,  NaO,  HO,  cPO*.  The  tribasic 
alkaline  phosphates  hare  a  strong:,  the  bibasic  a  weak  alkaline  reaction, 
while  the  simple  salts  hare  an  acid  reaction.  The  tribasic  salts  suffer  no 
change  by  ignition ;  the  bibasic  salts  are  thereby  concerted  into  pyro- 
phosphates, inasmuch  as  I  atom  of  water  is  driyen  off,  and  there  remain 
2  atoms  of  base  nnited  to  1  atom  of  acid,  e.  g,  2NaO,  HO,  cPO*  is  con- 
rerted  into  2NaO,  ^PO';  and  the  simple  phosphates  are  changed  into 
metaphosphates,  since  2  atoms  of  basic  water  are  CTolred,  and  there 
remains  bnt  1  atom  of  base  nnited  with  1  atom  of  acid,  e.  g.  NaO,  2H0, 
cPO*  becomes  NaO,  aPO*.  (Graham.)  All  soluble  ordinary  phosphates 
giro  white  precipitates  with  a  miztare  of  a  salt  of  magnesia,  sal-ammo- 
niac, and  ammonia  j  white  with  leadnsalts,  and  lemon-yellow  with  nitrate 
of  silver ;  the  tribasic  and  bibasic,  but  not  the  simple  salts,  precipitate 
^loride  of  barium.  Ordinary  phosphates  precipitate  baryta- water  and  1  ime* 
water.  Those  which  are  not  soluble  in  water  dissolre  easily  in  nitric 
acid ;  acetic  acid  dissolves  most  of  them,  though  less  easily,  and  the  lead- 
salt  and  the  salt  of  ferric  oxide  not  at  all.  They  are  also  slightly  soluble 
in  ammoniacal  salts,  especially  in  sal-ammoniac.  Ammonia  precipitates 
them,  both  from  solution  in  acids,  and  likewise,  for  the  most  part,  from 
their  solutions  in  ammoniacal  salts.  The  solution  of  ordinary  phosphates 
in  nitric  acid,  likewise,  when  it  does  not  contain  too  great  an  excess  of 
acid,  precipitates  lead-salts  white,  and  silrer-salts  lemon-yellow;  and  the 
precipitates  increase  in  quantity  when  ammonia  is  carefully  added  so  as 
not  completely  to  neutralize  the  acid. 

IT  Pkotpluaes  of  the  form  3M0  -f  2P0".  Phosphates  of  this  form  hare 
lately  been  discovered  by  Fleitmann  &  Henneberg.  The  soda-salt  is 
obtained  by  fusing  together  76*87  parts  of  metaphosphate  (the  vitreous 
metaphosphate  to  which  the  name  was  originally  applied)  and  1 00  parts 
of  anhydrous  pyrophosphate  of  soda,  or  187*27  metaphosphate  to  100 
parts  of  the  salt  3NaO,  P0^  The  materials  are  very  intimately  mixed 
by  pounding  in  a  mortar,  and  then  fused  in  a  platinum  crucible,  the  mass 
being  kept  for  some  time  in  the  liquid  state  and  continually  stirred.  The 
salt  when  cool  is  finely  pounded  and  digested  in  a  quantity  of  hot  water, 
not  q^uite  sufficient  to  dissolve  it :  an  excess  would  decompose  it.  The 
solution,  after  filtering,  is  left  to  evaporate  over  sulphuric  acid.  By  this 
process,  the  salt  is  obtained  in  the  form  of  a  white  crystalline  mass.  It 
IS  soluble  in  about  2  parts  of  cold  water,  the  solution  havitaga  weak  alkaline 
reaction.  From  this  salt,  other  phosphates  of  similar  constitution  may  be 
obtained  by  double  decomposition,  e.  g,  3AgO,  2P0';  3MgO,  2P0*;  dBaO, 
2P0»,  &c. 

Fho9phaies  of  the  form  OMO,  SPO*.  This  group  of  salts  has  likewise 
been  discovered  by  Fleitmann  &  Henneberg.  The  soda-salt  is  obtained  by 
fusing  together  100  parts  of  pyrophosphate  of  soda  and  307-5  of  meta- 
phosphate. It  is  very  unstable,  more  so  than  the  last.  It  may,  however, 
be  obtained  in  the  crystalline  form.  After  fusion,  it  forms  a  vitreouff 
mass,  like  metaphosphate  of  soda.  The  silver-salt,  6AgO,  5P0',  is 
obtained  by  double  decomposition :  it  is  easily  soluble  in  excess  of  the 
soda-salt. 

The  two  classes  of  salts  just  described  are  intermediate  between 
the  metaphosphates  and  the  pyrophosphates.  If  we  suppose  that  in 
all  salts  of  phosphoric  acid  the  acid  is  united  with  6  atoms  of  base. 


PHOSPHORUS  AND  HYDROGEN.  135 

the   whole  family  will  be  represented    by    the    following  continuoufl 
series. 

Commoii  Phosphate  6MO»  2P0* 

Pyrophosphate   6M0,  3PO* 

Fleitmann    &     Henneberg's   new)6M0,  4P0' 

Phosphates i6MO,  5PO* 

Metaphosphate  6MO,  6PO* 

(Ann.  Pharm.  65,  804.)  f 

Phosphorus  and  Htdrogen, 

A.      PrOTO PHOSPHIDE   OP   HyDROGEN? 

a.  The  yellow  powder  which,  according  to  H.  Rose  {Pogg,  12, 
549),  separates  daring  the  decomposition  of  phosphide  of  potassium 
by  water,  enters  into  fusion  at  a  temperature  at  which  phosphorus 
sublimes,  and  at  the  same  time  evolves  hydrogen  gas.  (Magnus,  Pogg, 
17,  527.) 

h.  1.  Phosphuretted  hydrogen  gas  obtained  by  moderately  heating  phos- 
phorus with  milk  of  lime,  collected  over  water  which  has  been  well  boiled 
and  is  still  warm,  and  exposed  to  strong  daylight  in  bottles  having  their 
necks  immersed  in  water,  deposits  yellow  flaKes,  which,  when  they  no 
longer  increase  in  quantity  and  the  gas  has  lost  its  spontaneous  inflam- 
mability, may  be  collectea,  freed  from  water  by  decantation,  and  dried  at 
50°.  If  the  gas  is  exposed  to  direct  sunshine,  the  yellow  colour  of  the 
flakes  is  less  brilliant.  2.  When  a  mixture  of  equal  measures  of  chlorine 
and  carbonic  acid  gases  is  passed  into  excess  of  phosphuretted  hydro- 
gen, the  same  deposit  is  produced,  but  so  finely  divided  that  it  cannot  be 
collected :  pure  ctilorine  produces  too  high  a  temperature,  and  consequently 
separates  pure  phosphorus. 

Greenish-yellow  flakes,  heavier  than  water,  smelling  like  phospho- 
rus, tasteless.  From  the  mean  of  several  experiments,  this  substance 
appears  to  be  PH.  Heated  in  a  stream  of  carbonic  acid  gas  to  a  tempera- 
ture above  175**,  it  is  resolved  into  hydrogen  gas  and  phosphorus. 
Exposed  under  boiled  water  to  the  solar  rays,  it  gradually  disappears, 
decomposing  the  water  with  evolution  of  hydrogen  gas  and  formation  of 
acid.  It  takes  fire  in  the  air  at  temperatures  between  140°  and  150°, 
according  as  it  is  more  or  less  finely  divided.  A  drop  of  strong  sulphuric 
acid  sets  it  on  fire  immediately,  producing  a  long  fiame.  It  dissolves  in 
dilute  nitric  acid  at  temperatures  between  SO"*  and  40°.  With  chlorine, 
it  forms  chloride  of  phosphorus  and  hydrochloric  acid.  It  is  decomposed 
by  copper  and  silver  salts.  It  is  insoluble  both  in  water  and  in  alcohol. 
(Leverrier,  Ann,  Chim,  Phys,  60,  175.) 

%  According  to  Paul  Thenard  {N.  Ann,  Chim.  Phys.  14,  5),  this 
substance  is  composed  of  two  atoms  of  phosphorus  and  one  of  hydrogen, 
or  in  100  parts,  98*43  P  +  1-57  H.  It  may  be  obtained  in  a  state  of 
purity  by  the  action  of  strong  hydrochloric  acid  on  phosphide  of  calcium, 
rCa',  phosphuretted  hydrogen  gas  being  produced  at  the  same  time. 

5PCa«  +  lOHa  r=  10  CaCl  +  P«H  +  3PH». 

It  is  probable,  however,  that  the  liquid  phosphide,  PH^  is  first  produced 
{vid,  p.  148),  and  immediately  resolved  by  the  excess  of  acid  into  solid 


136  PHOSPHORUS. 

phosphide  and.  phospho retted  hydrogen  gas.  As  soon  as  the  evolution  of 
phosphuretted  hydrogen  is  at  an  end,  the  insolnble  residue  is  to  be  washed 
and  afterwards  dried  in  vacao.  Solid  phosphide  of  hydrogen  may  also  be 
obtained  by  passing  spontaneously  inflammable  phosphuretted  hydrogen 
gas  through  concentrated  hydrochloric  acid,  care  being  taken  to  preyent 
the  stoppage  of  the  tube. 

This  substance  is  yellow  when  freshly  prepared,  but  becomes  orange- 
coloured  by  exposure  to  light ;  it  is  inodorous ;  takes  fire  at  200°,  also 
whenstrucK  on  the  anyil  by  a  hammer;  it  is  not  altered  by  dry  air  at 
ordinary  temperatures,  slowly  by  damp  air.  Heated  in  hydrogen  gas,  it 
distils  and  is  decomposed,  yielding  phosphuretted  hydrogen  gas.  It  first 
assumes  an  orange-red  colour ;  then,  at  a  higher  temperature,  phosphorus 
distils  over ;  the  colour  becomes  dark  grey ;  and,  after  a  further  applica- 
tion of  heat,  the  substance  disappears  entirely.  The  only  liquid  which 
dissolves  it  without  decomposition  is  the  liquid  phosphide  of  hydrogen. 
Chlorine,  perchluride  of  phosphorus,  and  sulphuric  acid  decompose  it 
instantly.  Solution  of  caustic  potassa  in  absolute  alcohol  dissolves  it  with 
evolution  of  phosphuretted  hydrogen  gas  mixed  with  more  or  less  free 
hydrogen,  and  there  remains  a  red  liquid  which  quickly  changes :  this, 
after  a  few  hours,  becomes  colourless,  hydrogen  is  evolved,  and  hyposul- 
phite of  potassa  deposited.  On  the  application  of  heat,  the  decomposition 
is  immediate.  Water  added  to  the  red  liquid  produces  a  dirty-yellow 
precipitate;  acids,  a  greenish-yellow  precipitate  of  phosphoric  oxide. 
Solid  phosphide  of  hydrogen  added  to  solution  of  sulphate  of  copper,  pro- 
duces phosphide  of  copper  mixed  with  metallic  copper.  With  chlorate  of 
potassa  it  detonates  violently  when  struck  or  heated ;  less  violently  with 
oxide  of  silver  or  mercuric  oxide.  With  oxide  of  copper  it  detonates  when 
heated,  and  often  with  great  violence.  Hence  all  experiments  with  this 
substance  must  be  conducted  with  great  caution. 

The  greenish  residue  obtained  in  the  preparation  of  spontaneously 
inflammable  phosphuretted  hydrogen  by  heating  phosphorus  with  milk 
of  lime,  or  by  the  action  of  water  on  phosphide  of  calcium,  appears,  accord- 
ing to  Th Guard's  observations,  to  be  isomeric  with  the  preceding.  It  is 
decomposed  by  heat.  Like  the  yellow  phosphide,  it  is  completely  dissolved, 
with  evolution  of  phosphuretted  hydrogen  gas,  by  alcoholic  solution  of 
potassa;  the  solution  is  blood-red.  It  is  not  altered  by  boiling  with 
hydrochloric  acid.  IT 

I 

B.    Phosphuretted  Hydrogen  Gab.    PH*. 

Pkosphorwasserstoff-gasy  Phosphorlufi,  phosphorhaUiges,  gephoiphartes 
Wasserstof-gas,  Oas  hydrogine  phosphori,  Gashydrogenium  phStphiratum, 
This  gas  appears  sometimes  to  occur  in  nature  as  the  cause  of  Ignes  Fatui 
and  similar  luminous  appearances. 

Phosphuretted  hydrogen  gas  occurs  in  two  difierent  states : 

1.  Spontaneously  inflammable  PhosphuretUd  Hydrogen:  takes  fire  in 

the  air  at  ordinary  temperatures,  and   under  the  ordinary  atmospheric  j 

pressure.  ] 

2.  1^0 n-spontaneously inflammable PhotphureUed  Hydrogen:  takes  fire  ' 
only  at  elevated  temperatures,  or  under  diminished  pressure. 

Formation.  This  compound  is  produced  when  phosphorus  and  hydro- 
gen come  in  contact  at  the  moment  of  separation  from  other  combinations, 
that  is  to  say,  in  the  nascent  state.     If  the  hydrogen  has  onoe  assumed 


n 


PHOSPHURETTED   HYDROGEN.  137 

the  gaseous  state^  it  is  no  longer  capable  of  entering  into  this  combination. 
When  pbosphorns  is  kept  for  some  time  in  a  state  of  fusion  in  hydrogen 
gas,  vapour  of  phosphorus  diffuses  itself  through  the  gas,  imparting  to  it 
the  odonr  of  garlic  and  the  property  of  emitting  light  In  contact  with 
oxygen  gas;  without,  however,  the  occurrence  of  an  actual  chemical  com- 
bination between  the  phosphorus  and  hydrogen.  (Fourcroy  &  Vauque- 
lin,  Ann.  Ckim,  21, 202.) 

Formation  of  the  more  infiammahU  gcu.  1.  The  compounds  of  phos- 
phorus with  the  alkali-metals  are  resolved,  by  contact  with  water,  into  an 
alkaline  hypophosphite  and  phosphu retted  hydrogen. — 2.  Phosphide  of 
zinc,  tin,  or  iron,  with  aqueous  sulphuric  or  hydrochloric  acid,  yields  a 
metallic  sulphate  or  chloride  and  phosphuretted  hydrogen  gas.  Zino 
exposed  in  contact  with  granulated  phosphorus  to  the  action  of  dilute 
sulphuric  acid,  evolves,  not  phosphuretted  hydrogen  as  stated  by  Davy, 
but  pure  hydrogen  gas,  with  which,  when  the  acid  is  heated,  vapour  of 
phosphorus  becomes  mixed.  (Dumas,  Ann,  Chi/m,  Phys,  31,  135.) — 
3.  Phosphorus  heated  in  an  aqueous  solution  of  a  fixed  alkali,  yields 
phosphuretted  hydrogen  gas  together  with  a  hypophosphite  and  phosphate 
of  the  alkali.  Such  an  action  is  exerted  by  potassa,  soda,  lithia,  baryta, 
strontia,  and  lime,  and,  according  to  Raymond,  by  oxide  of  zinc  and  pro- 
toxide of  iron.  Potassa  causes  an  evolution  of  gas  even  at  15^  The 
affinity  of  phosphorus  for  hydrogen  +  that  of  phosphorus  for  oxygen + 
the  predisposing  affinity  of  the  idkali  for  phosphoric  and  hypophospho- 
rous  acid,  overcomes  the  powerful  affinity  between  hydrogen  and  oxygen. 
From  the  very  beginning  of  the  action,  the  phosphuretted  hydrogen 
gas  is  mixed  with  more  or  less  free  hydrogen,  and  there  is  likewise  a 
certain  quantity  of  phosphate  produced;  but  as  the  boiling  is  continued 
and  the  solution  becomes  more  concentrated,  the  quantity  of  hydrogen  gas 
continually  increases;  because  agreater  and  greater  quantity  of  the  alkaline 
hypophosphite  is  resolved,  together  with  water,  into  hydrogen  gas  and  a 
phosphiteof  the  alkali  (II.,  114).  H,  Rose. — 4.  When  hypophosphites  are 
heated,  the  phosphuretted  hydrogen  evolved  is  generally  of  the  more 
inflammable,  more  rarely  of  the  less  inflammable  variety,  mixed  with  a 
certain  quantity  of  vapour  of  phosphorus  and  free  hydrogen  gas.  (H. 
Rose.) — 5,  In  the  putrefaction  of  organic  bodies  containing  phosphorus : 
hence  the  odour  of  decayed  fish. 

Formation  of  the  less  inflammable  gas.  1.  When  the  hydrate  of  phos- 
phorous acid  (H.  Davy),  or  of  hypophosphorous  acid  is  heated.  (Dulonff.)— * 
2.  When  zinc  or  iron  is  dissolved  in  aqueous  phosphorous  acid  ^Berzelius), 
or  zino  in  a  mixture  of  aqueous  phosphorous  acid  and  sulpnuric  acid. 
(Wbhler.) — 3.  When  phosphorus  is  boiled  with  hydrate  of  potassa  and 
alcohol,  the  non-inflammable  gas  is  evolved  mixed  with  hydrogen  gas  and 
alcohol  vapour,  and  there  remains  hypophosphite  of  potassa  and  a  small 
quantity  of  phosphate,  together  with  excess  of  potassa.  (H.  Rose.) 
Grotthuss  (Ann.  Chim.  64,  32,  also  M.  Gehl.  5,  608;  further  Schw.  32, 
274),  took  this  mixture  for  a  peculiar  gas,  which  he  called  Fhospho-carbu- 
retted  Hydrogen, — 4.  When  phosphide  of  calcium  is  decomposed  by  con- 
centrated hydrochloric  acid.  (Dumas.) — 5.  Phosphorus,  under  the  influ- 
ence of  light,  decomposes  water,  producing  phosphoric  oxide  and  phos- 
phuretted hydrogen  gas,  which  remains  dissolved  in  the  water. 

A  flask  was  completely  filled  with  granulated  phosphorus  and  water, 
and  connected  with  a  bent  tube  filled  with  water,  the  other  end  of  the 
tube  dipping  under  mercury.  After  six  weeks'  exposure  to  the  rays  of 
the  summer  sun,  the  following  effects  were  produced.     1.  The  water  in 


138  PHOSPHORUS. 

the  tube  reddened  litmus,  gave  a  white  precipitate  with  solution  of  cor- 
rosive sublimate,  brown  with  solution  of  silver  and  brown-black  after  a 
time  with  solution  of  sulphate  of  copper,  out  of  contact  of  air. — 2.  The  flask 
was  connected  with  a  gas-delivery  tube  filled  with  water  and  heated  to 
the  boiling  point.  Phospburetted  hydrogen  gas,  equal  in  volume  to  about 
^  of  that  of  the  flask,  was  evolved  together  witn  the  aqueous  vapour. 
This  gas  was  not  spontaneously  inflammable :  solution  of  sulphate  of  copper 
absorbed  about  90  per  cent,  of  it,  producing  a  brown-black  precipitate. 
The  water  after  thorough  boiling  exhibited,  when  rapidly  filtered,  the  same 
reactions  as  the  water  out  of  the  bent  tube ;  but  it  no  longer  preci- 
pitated solution  of  sulphate  of  copper  in  a  closed  vessel  completely  filled 
with  it.  The  phosphorous  acid  is  probably  accidental,  inasmuch  as  the 
granulation  of  the  phosphorus  and  the  filling  of  the  flask  with  water  were 
performed  during  the  heat  of  summer.  It  is  remarkable  that  the 
filtered  water  of  the  flask  difi'used  white  fumes  through  the  vessel,  and 
smelt  of  phosphorus, — an  efiect  which  cannot  be  due  to  the  small  quantity 
of  phosphorous  acid  present,  but  indicates  a  certain  amount  of  solubility 
of  the  phosphorus  in  water.  (Gm.)  Phosphorus  kept  under  water  and 
exposed  to  light  (in  the  dark  the  effect  is  produced  less  strongly  and  more 
slowly)  imparts  to  the  water  a  peculiar  odour  and  the  property  of  giving 
a  dark-coloured  precipitate  with  nitrate  of  silver  or  subnitrate  of  mercury; 
this  latter  properVjr,  however,  is  lost  by  exposure  to  the  air.  (Phillips,  Ann. 
Fhil.  21,  470.)  Water  in  which  phosphorus  is  immersed  acquires  a  pe- 
culiar taste,  a  poisonous  action,  and  the  property  of  emitting  light  when 
mixed  with  hot  water.  (Murray,  Ann,  Phil,  16,  230.)  When  phosphorus 
is  kept  for  some  time  under  water  in  a  well-stopped  bottle,  it  emits 
light  every  time  the  vessel  is  shaken,  and  often  gives  a  transient  light 
even  when  no  agitation  takes  place.  On  opening  the  bottle,  this  appear- 
ance ceases,  and  does  not  show  itself  again  till  the  vessel  has  been  Icept 
well  closed  for  some  time.  (Berzelius,  Lehrb.  1,  222.)  This  luminosity  dis- 
appears after  several  days,  if  the  bottle  be  kept  with  the  stopper  turned 
downwards  and  shaken  every  day, — ^but  reappears  on  opening  it  again 
for  an  instant :  it  appears  to  arise  from  the  combustion  of  the  phosphorus 
or  phospburetted  hydrogen  gas  in  very  highly  rarefied  oxygen  gas.    (Gm.) 

Preparation  of  the  more  injlammahle  ^as.  1.  By  bringing  phosphide 
of  potassium,  barium,  or  calcium  in  contact  with  water.  Thomson  fills  a 
small  tubulated  retort  three-fourths  with  thoroughly  boiled  water  and  one- 
fourth  with  nitric  acid — introduces  phosphide  of  calcium  through  the 
tubulure — fills  the  neck  likewise  with  boiled  water — and  applies  a  gentle 
heat.  One  ounce  of  phosphide  of  calcium  yields  70  cubic  inches,  and  IB 
grammes  ^ield  1  litre  of  gas.  Dumas  causes  water  or  very  dilute  hydro- 
chloric acid  to  come  in  contact  with  phosphide  of  barium  or  phosphide  of 
calcium  placed  at  the  top  of  a  bell-jar  filled  with  mercury.  The  gas 
obtained  oy  means  of  phosphide  of  barium  and  water  contains,  according 
to  Dumas,  43*2  measures  in  a  hundred  of  free  hydrogen  gas;  that  obtained 
with  phosphide  of  calcium  and  water  contains  13;  and  when  phosphide 
of  calcium  and  dilute  hydrochloric  acid  are  the  acting  substances,  the  gas 
first  evolved  contains  7,  and  that  last  evolved  13  per  cent  Buff*  likewise 
found  between  13*5  and  14*5  per  cent,  of  free  hydrogen  in  the  gas  ob- 
tained by  the  mutual  action  of  phosphide  of  calcium  and  water. 

2.  By  heating  phosphorus  with  aqueous  solutions  of  the  alkalis.  — 
a.  Gengembre  boils  1  part  of  phosphorus  with  2  parts  of  concentrated  solu- 
tion of  potassa  in  a  gas-generating  vessel.  H;  Rose  also  recommends  solution 


PHOSPHURETTED  HTDROGEN.  1S9 

of  potassa  concentrated  as  much  as  possible,  and  likewise  that  it  be  pure, 
since  imparities  produce  frothing.  The  liquid  is  heated  only  so  long  as 
the  gas  is  evolved  without  the  application  of  a  stronger  heat;  after  that, 
the  quantity  of  free  hydrogen  increases.  (H.  Rose.)  The  gas  obtained 
always  contains  62-5  measures  per  cent,  of  free  hydrogen.  (Dumas.)  As 
the  alkaline  liquid  only  fills  a  small  part  of  the  vessel,  the  air  which 
remains  in  it  often  produces  explosions  with  the  portions  of  gas  first 
evolved, — whereby  the  vessel  is  burst,  or  at  all  events,  the  water  is  forced 
back  into  it.  To  prevent  these  explosions,  the  air  is  either  deprived  of 
part  of  its  oxygen  by  the  introduction  of  burning  sulphur  matches  before 
the  gas-delivery  tube  is  adjusted  in  its  place — by  which  means  the  vio- 
lence of  the  explosions  is  diminished ;  or  what  is  better — the  bottle  is 
only  loosely  covered  with  the  stopper  of  the  gas-delivery  tube,  when  the 
heat  is  first  applied  (this  is  H.  Rose's  plan)  and  not  closed  air-tight  till 
the  gas  which  escapes  near  the  stopper  begins  to  burn  with  a  brilliant 
fiame.  If  the  liquid  together  with  the  melted  phosphorus  should  pass 
over,  the  phosphorus  as  it  cools  may  stop  up  the  tube  and  thereby  cause 
the  bottle  to  burst  when  the  heating  is  continued. — 6.  Raymond  heats 
in  a  gas-generating  vessel  one  part  of  phosphorus  with  16  parts  of  hydrate 
of  lime  and  4  parts  of  water  (Ann.  Chim,  10,  19).  Dry  hydrate  of  lime 
heated  with  phosphorus  yields  a  gas  containing  a  much  larger  quantity 
of  free  hydrogen  than  that  prepared  with  solution  of  potassa.  The 
quantity  of  free  hydrogen  increases  considerably  on  further  heating,  by 
which  the  hypophosphite  of  lime  is  converted  into  phosphate.  (H.  Rose.) 
The  gas  evolvea  by  heating  phosphorus  with  milk  of  lime  is  found,  when 
collected  in  7  separate  portions,  to  contain  in  100  measures, — first  34 
measures,  then  27,  then  39,  then  44,  then  50,  then  60,  then  86,  and  ul- 
timately, when  the  vessel  is  heated  nearly  to  redness,  from  89  to  90 
measures  of  free  hydrogen  gas.  (Dumas.) 

Preparation  of  the  less  inflammable  gas,  1.  By  heating  crystallized 
phos|>horous  acid  m  the  gas-generating  apparatus.  (H.  Davy.^  Phosphatic 
acid  may  also  be  used  for  this  purpose.  The  gas  prepared  in  green  glass 
retorts  is  pure,  only  the  portions  last  evolved  containing  a  little  free  hy- 
drogen ;  but  that  which  is  prepared  in  white  glass  retorts  contains 
hydrogen  gas,  because  an  alkaline  phosphite  is  produced,  with  separation 
of  silica, — and  this  when  heated  evolves  hydrogen.  (H.  Rose.) — 2.  The 
same  gas  is  evolved  on  heating  hydrated  hypophosphorous  acid.  (H.  Rose; 
Dumas.)  The  first  portions  of  gas  evolved  by  methods  1  and  2  are  per- 
fectly pure;  the  latter  portions  deposit  phosphorus  (from  the  action  of  a 
greater  degree  of  heat  t)  and  contain,  in  100  measures,  from  17  to  25  mea- 
sures of  free  hydrogen.  (Dumas.) — 3.  B^  decomposing  phosphide  of 
calcium  by  rather  strong  hydrochloric  acid.  Ten  cubic  centimetres  of 
concentrated  hydrochloric  acid  being  placed  over  mercury  in  a  glass  jar,  a 
gramme  of  phosphide  of  calcium  pounded  and  wrapped  up  in  paper  is 
rapidly  passed  up  the  mercury  before  it  has  time  to  take  fire.  Decom- 
position ensues,  with  powerful  development  of  heat  and  separation  of 
phosphorus.  The  gas  obtained  is  quite  pure,  or  else  contains  not  more 
than  from  1  to  5  per  cent,  of  free  hydrogen.  Hydrochloric  acid  diluted 
with  an  equal  bulk  of  water  likewise  evolves  a  pure  gas,  with  separation 
of  phosphorus ;  but  the  decomposition  is  slower,  because  the  development 
of  heat  is  less.  (Dumas.) 

To  detect  the  free  hydrogen  mixed  with  phosphuretted  hydrogen,  the 
gas  is  brought  into  contact  with  solution  of  chloride  of  lime  (Dalton),  or 
of  sulphate  of  copper,  oorrosire  sublimate,  or  nitrate  of  silver.  (Dumas  ; 


140  PHOSPHORUS. 

H.  Rose.)     These  bodies  decompose  phosphnretted  hydrogOD,  bat  leave 
unchanged  the  free  hydrogen  which  may  be  mixed  with  it. 

Froperties  of  the  more  inflammable  and  less  infiammahU  gases.  Colour- 
less. Sp.  gr.  (I.,  279.)  The  free  hydrogen  which  is  frequently  mixed 
with  the  gas  diminishes  its  specific  gravity  considerably;  hence  it  was 
formerly  given  much  lower.  The  gas  smells  like  stinking  fish :  or  more 
properly  speaking, — the  fish  in  a  state  of  decomposition  smell  like  the  gas, 
since  they  evolve  it.  It  is  irrespirable^  exerting  a  positively  deleterious 
action.  It  does  not  support  combustion,  but  takes  fire  in  the  air,  some- 
times spontaneously,  sometimes  when  heated;  has  no  action  on  vegetable 
colours. 

H.  Rose.         Dumas.  H.  Dsyy.  Levenier. 

Calcolation.  a  b  ah 

P  ....  31-4  ....  91-28  ..„  91-32  ....  9412  ....  91-51  ....  833  ....  91-36....91-63  ....  91-31 
3H  ....     3     ....     8-72   ....  8-63   ....  5-88  ....   849  ....  16*7  ....    8-64...  8-37  ....    8-69 

PH»        34-4     10000     10000     10000     10000     1000     100-00  10000     10000 

Volume.       Sp.gr.  Or:  Vol.  Sp.  gr. 

Vapour  of  phosphorus    1  4*3539  i  1-0885 

Hydrogen  gas 6  0-4158  \\  01039 

Phosphuretted  Hydrogen  Gas  .  4  47697  1     1-1924 

(H*P  =  3  .  6-2398  +  196*14  =r  214*86.    Berzelius.) 

The  eas  a  examined  by  Dumas  and  Leverrier  was  spontaneously 
inflammable ;  the  gas  6,  inflammable  only  when  heated.  According  to 
these  experimenters,  the  two  gases  are  differently  constituted,  the  spon- 
taneously inflammable  gas  having,  according  to  Dumas,  the  composition 
PH'  or  PH*;  4  volumes  of  it  contain  1^  measures  of  vapour  of  phospho- 
rus, and  6  measures  of  hydrogen  gas  {vid,  seq.). 

Decompositions,  The  spontaneously  inflammable  gas  exposed  to  light 
over  mercury  or  well-boiled  water  deposits  nothing,  (unless  vapour  of 
phosphorus  were  previously  mixed  with   it,)    and  remains   unaltered. 

SH.   Rose.)      The    less   inflammable   gas  likewise   remains  unaltered. 
Graham.) 

1.  When  a  succession  of  electric  sparks  is  passed  through  the  sponta- 
neously inflammable  gas,  the  phosphorus  is  deposited  in  tne  form  of  a 
red  film,  and  the  gas  is  converted  into  1^  (properly  1^)  times  its  volume 
of  pure  hydrogen.  (Dalton.)  The  less  inflammable  gas  when  electrified 
(for  a  shorter  time?),  deposits  phosphorus  and  becomes  spontaneously 
inflammable.  (Graham.) 

2.  Rapid  Combustion.  The  spontaneously  inflammable  gas  takes  fire 
at  ordinary  temperatures  and  under  ordinary  pressures  in  contact  with 
air  or  oxygen  gas.  Even  when  passed  through  a  tube  7  feet  long,  and 
surrounded  with  a  freezing  mixture  cold  enough  to  solidify  mercury,  it 
takes  fire  on  escaping  into  air  of  the  temperature  of  —15°  (—5®  F.).  (H. 
Rose.)  The  inflammation  of  single  bubbles  of  the  gas,  as  they  escape  into 
the  air,  is  attended  with  a  very  vivid  light  and  the  formation  of  a  thick, 
white,  ring-shaped  cloud  of  hydrated  phosphoric  acid.  In  oxygen  gas  the 
combustion  is  exceedingly  brilliant,  resembling  flashes  of  lightning,  and, 
when  the  quantity  is  large,  attended  with  fracture  of  the  vessel.  When 
sufficient  oxygen  is  present,  the  products  of  the  combustion  are  phospho- 
ric acid  and  water;  but  a  small  portion  of  the  phosphorus  is  converted 
into  phosphoric  oxide,  which  is  deposited  on  the  water  and  on  the  vessels 


PHOSFHURETTED  HYDROGEN.  141 

in  the  form  of  a  yellowish-red  film.  The  less  inflammable  gas  does  not 
take  fire  in  air  or  oxygen  gas  at  ordinary  temperatures,  either  under  ordi- 
nary or  increased  atmospheric  pressure;  under  ordinary  pressure,  it 
inflames  at  149*"  (300°  F.).  (H.  Davy.)  At  ordinary  temperatures 
inflammation  does  not  take  place  unless  the  gaseous  mixture  is  rarefied. 
(Houton  Labillardi^re.)  A  strong  glass  tube  being  surrounded  with  a 
piece  of  stout  wire-gauze  (because  it  is  very  liable  to  burst),  and  placed 
m  a  very  inclined  position  over  the  mercurial  trough,  a  mixture  of  oxygen 
and  the  less  inflammable  phosphuretted  hydrogen  is  passed  up  iuto  it ;  if 
it  be  then  raised  into  the  upright  position,  so  as  to  expand  the  gaseous 
mixture  by  about  2  decimetres,  explosion  immediately  takes  place. 
(Houton  Labillardiere.)  Explosion  by  alteration  of  level  takes  place 
with  peculiar  &cility  when  there  is  an  excess  of  phosphuretted  hydrogen 
present ;  e.  g,  with  2  measures  of  the  latter  and  1  measure  of  oxygen ;  a 
mixture  of  1  measure  of  phosphuretted  hydrogen  with  1^  measures  of 
oxygen  scarcely  ever  takes  fire  on  setting  the  tube  upright,  if  the  oxygen  be 
introduced  first.  (Dumas.)  If  a  mixture  of  1  volume  of  the  less  inflammable 
gas  and  3  volumes  of  oxygen  be  introduced  into  a  tube  standing  over  mer- 
cury, and  already  con  taming  a  small  quantity  of  oxygen  gas,  no  inflamma- 
tion takes  place ;  but  if  this  effect  be  brought  about  oy  the  application  of 
heat,  every  bubble  of  the  mixture  which  is  brought  in  contact  with  the 
remaining  oxygen  after  the  tube  has  completely  cooled,  takes  fire.  (H. 
Rose.)  The  less  inflammable  gas  mixed  with  air  and  kept  over  mercury 
at  the  ordinary  pressure,  invariably  explodes  after  a  few  hours.  (H. 
Rose.)  When  exploded  with  excess  of  air  or  oxygen  gas,  1  volume  of 
phosphuretted  hydrogen  gas,  whether  spontaneously  inflammable  or  not, 
consumes  2  volumes  of  oxygen  gas.  According  to  page  140,  4  volumes  of 
phosphuretted  hydrogen  gas  contain  6  volumes  of  hydrogen,  which  con- 
sume 3  volumes  of  oxygen  in  order  to  form  water,  and  1  volume  of  vapour 
of  phosphorus,  which  requires  5  volumes  of  oxyeen  to  convert  it  into 
phosphoric  acid.  Or,  1  volume  of  phosphuretted.  hydrogen  gas  contains 
5  ^  vol.  of  hydrogen,  which  require  }  vol.  oxygen, — and  ^  vol.  vapour 
of  phosphorus,  which  requires  J  vol.  oxygen ;  and  f  H-  |  =  2.  The 
spontaneously  inflammable  gas  introduced  in  bubbles  into  excess  of  oxygen, 
deposits  part  of  its  phosphorus  in  the  form  of  a  yellowish-red  film,  and 
then  consumes  a  smaller  quantity  of  oxygen.  To  obtain  perfect  com- 
bustion, Dumas  mixes  the  spontaneously  inflammable  gas  with  an  equal 
volume  of  carbonic  acid,  and  similarly  with  the  oxygen — brings  the  two 
gaseous  mixtures  in  contact — and  inflames  the  mixture  by  heating  it  to 
1 20°.  In  this  case,  accordinc^  to  Dumas,  1  volume  of  the  spontaneously 
inflammable  gas  consumes  only  1  *83  vol.  oxygen  ;  and  he  supposes,  since 
the  explosion  is  accompanied  by  only  a  feeble  light,  that  phosphorous 
instead  of  phosphoric  acid  is  produced, — a  supposition  which  Rose  justly 
regards  as  improbable.  According  to  Buff  also,  1  volume  of  spontaneously 
inflammable  phosphuretted  hydrogen  mixed  with  3  volumes  of  carbonic 
acid,  and  then  with  excess  of  oxygen,  consumes  2  volumes  of  the  latter  when 
exploded.  Also,  according  to  Dalton's  later  assertion,  1  volume  of  the 
spontaneously  inflammable  gas  consumes  2  volumes  of  oxygen.  The  less 
inflammable  gas  exploded  with  excess  of  oxygen,  absorbs  somewhat  less 
than  2  volumes,  because  part  of  the  phosphorus  is  precipitated  unbumt. 
(H.  Davy.)  But  according  to  Dumas,  the  quantity  of  oxygen  consumed  is 
exactly  2  volumes.  When  the  quantity  of  oxygen  in  the  mixture  is 
insaficient  for  complete  combustion,  the  phosphorus  bums  first,  and  pure 
hydrogen  gas  is  left,  its  volume  sometimes  amounting  to  \  more  than  that 


142  PHOSPHORUS. 

of  tlie  pkosphuretted  hydrogen.  (H.  Davy.)  When  a  mixture  of  1  Tolome 
of  the  less  inflammable  ^as  with  l^  vol.  oxygen  is  inflamed  in  a  narrow 
tube  bj  the  electric  spai^^  it  is  resolved,  without  deposition  of  phospho- 
rus, into  water  and  phosphorous  acid,  a  small  residue  being  left,  consist- 
ing sometimes  of  hydrogen,  sometimes  of  hydrogen  and  oxygen,  sometimes 
of  phosphuretted  hydrogen:  1^  vol.  hydrogen  gas  requires  |  vol.  oxy- 
gen, and  ^  vol.  vapour  of  phosphorus  requires  |  vol.  oxygen  to  form 
phosphorous  acid ;  and  f  +  f  =  1  i.  (Dumas.)  A  mixture  of  2  volumes 
of  phosphuretted  hydrogen  and  1  volume  of  oxygen,  exploded  b^  rarefac- 
tion, deposits  a  large  quantity  of  phosphorus,  and  leaves  a  residue  con- 
sisting of  pure  hydrogen  and  phosphuretted  hydrogen.  (Dumas.) 

3.  Slow  Combustion.  When  spontaneously  inflammable  phosphuretted 
hydrogen  gas  and  oxygen  gas  are  brought  together  in  a  tube  only  0*3  of  an 
inch  in  diameter,  no  combustion  takes  place,  because  the  sides  of  the  tube 
exert  a  cooling  action.  (Dalton.)  In  this  action,  according  to  Thomson^ 
one  volume  of  phosphuretted  hydrogen  absorbs  half  a  volume  (more  cor- 
rectly |)  of  oxygen,  and  forms  phosphorous  acid,  whilst  one  volume  (or  more 
correctly  1^)  of  pure  hydrogen  remaius.  Both  varieties  of  phosphuretted 
hydrogen  gas,  when  kept  over  water  containing  air,  undergo  a  similar 
slow  combustion,  and  the  more  inflammable  gas  loses  its  spontaneous 
inflammability. 

4.  Phosphuretted  hydrogen  gas  takes  fire  in  chlorine  gas  at  ordinary 
temperatures,  bums  with  a  brilliant  greenish- white  light,  and  combines 
with  4  measures  of  chlorine,  producing  hydrochloric  acid  and  pentachloride 
of  phosphorus.— 1^  vol.  hydrogen  gas  requires  l\  vol.  chlorine,  and  ^  vol. 
vapour  of  phosphorus  requires  2^  vol.  chlorine;  and  1^  +  2^  =  4. 
According  to  Thomson,  one  volume  of  the  more  inflammable  gas  consumes 
only  3  volumes  of  chlorine ;  but  with  the  less  inflammable,  Davy  found 
the  ratio  of  1  : 4. — 5.  Bromine  precipitates  phosphorus  from  the  spontane- 
ously inflammable  gas,  and  forms  hydrobromic  acid,  with  evolution  of 
heat.  (Balard.) — 6.  Iodine  introduced  into  the  spontaneously  inflammable 
ffas  produces  iodide  of  phosphorus  and  hydriodic  acid,  together  with  free 
hydrogen.  (Thomson.)  The  hydrogen  was  in  all  probability  previously 
mixed  with  the  gas. — 7.  Sulphur  heated  in  the  gas  produces  hydrosulphu- 
ric  acid  and  sulphide  of  phosphorus.  One  volume  of  phosphuretted 
hydrogen  gas  should  yield  1^  vol.  of  hydrosulphuric  acid  gas ;  but  as  this 
^s  is  absorbed  by  sulphide  of  phosphorus,  the  quantity  actually  obtained 
IS  less.  From  one  volume  of  the  spontaneously  inflammable  gas,  Thomson 
obtained  one  volume,  and  Vauquelin  ]  '1  volume  of  hydrosulphuric  acid 
gas;  while  from  one  volume  of  the  less  inflammable  gas,  Dumas  obtained 
1*35,  and  Davy  2  volumes  of  hydrosulphuric  acid  gas. 

8.  Many  metals,  as  potassium,  zinc,  iron,  copper,  and  antimony, 
abstract  phosphorus  from  the  gas  at  high  temperatures,  forming  metallic 
phosphides,  and  leaving  1^  voL  of  pure  hydrogen  gas.  From  one  volume 
of  the  more  inflammable  gas,  potassium  separates  1*33  vol.  of  pure  hydro- 
gen, according  to  Sir  H.  Davy  and  Dalton,  and  1  *5  vol.,  according  to 
Gay-Lussac  &  Thenard;  with  zinc  or  antimony.  Buff  likewise  obtained 
1'5  vol.  One  volume  of  the  less  inflammable  gas  yields  with  red-hot 
iron  or  copper,  1*49  and  1*52  vol.  hydrogen  gas  (Dumas);  with  retl-hot 
copper,  1-5  (Bufl);  with  potassium  |j)robably  from  the  presence  of  mois- 
ture], 2  volumes.  (H.  Davy.) 

9.  Phosphoric  oxide,  sulphurous  acid,  sulphuric  acid,  chlorine  water, 
hjrpochlorous  acid,  hypochlorite  of  lime,  nitrous  oxide,  nitric  oxide,  nitric 
acid,  arsenic  acid,  heavy  metallic  oxides,  and  their  solutions  in  acida 


PHOSPHUKETTED  HYDROGEN.  143 

decompose  phospburetted  hydrogen  gas.  When  this  gas  is  passed  through 
water  in  wnich  phosphoric  oxide  is  diffused^  the  latter  becomes  white, 
because,  according  to  Mulder,  a  compound  of  phosphoric  acid  with  phos- 
phnretted  hydrogen  gas  is  produced, — ^more  probably,  ho  werer,  because  the 
two  compounds  are  resolved  into  water  and  phosphorus.  Sulphurous  acid 
gas  produces  with  the  spontaneously  inflammable  gas,  water  and  sulphide 
of  phosphorus.  Anhydrous  sulphuric  acid  introduced  into  the  more 
inflammable  gas,  produces  sulphurous  acid  gas,  with  separation  of  phos- 
phorus and  sulphur;  oil  of  vitriol  with  the  same  gas,  forms  sulphur, 
phosphorus,  and  hydrosulphurio  acid.  Hypochlorous  acid  gas  detonates 
with  spontaneously  inflammable  phosphuretted  hydrogen,  and  aqueous 
hypochlorous  acid  yields  phosphoric  and  hydrochloric  acid.  (Balard.) 
Solution  of  hypochlorite  of  lime  (chloride  of  lime)  acts  in  the  same  way. 
(Dalton. )  Phosphuretted  hydrogen  gas  detonates  by  the  electric  spark 
with  nitrous  oxide  or  nitric  oxiile  gas ;  is  slightly  decomposed  by  hyponi- 
tric  acid,  but  violently  and  with  great  evolution  of  heat  by  concentrated 
nitric  acid.  The  spontaneously  inflammable  ^as  is  decomposed  by  con- 
tact with  arsenic  acid  {Graham;  probably  with  formation  of  water  and 
phosphide  of  arsenic) ;  slowly  by  mercurous  oxide,  and  not  at  all  bv  mer- 
curic oxide.  (Graham.)  By  dinoxide  or  protoxide  of  copper  slightly 
heated,  it  is  easily  resolved  into  water,  phosphide  of  copper,  and  phospho- 
ric acid.  ^H.  Rose.)  It  precijpitates  l^ui-salts  very  slowlv,  copper-salts 
more  tjuicKly,  and  the  salts  of  the  noble  metals  most  quickly  of  all.  The 
precipitates  are  mostly  black,  and  consist,  sometimes  of  a  metallic  phos- 
phide, as  in  the  case  of  copper ;  sometimes  of  a  combination  of  the  metallic 
phosphide  with  the  metallic  salt,  as  with  nitrate  or  sulphate  of  mercuric 
oxide,  which  give  white  precipitates ;  sometimes  of  reduced  metal,  the  liquid 
retaining  phosphoric  acid,  as  in  the  case  of  silver  and  gold.  (H.  Rose.) 
The  gas  obtained  from  phosphorus  and  alcoholic  solution  of  potassa  does 
not  precipitate  the  salts  of  antimony,  bismuth,  zinc,  cadmium,  tin,  lead, 
iron,  cobalt,  nickel,  copper  (?),  platinum,  rhodium,  or  iridium  from  their 
aqueous  solutions ;  but  gives  precipitates  with  solutions  of  tellurium,  mer- 
cury, silver,  gold,  and  palladium,  the  product  in  all  cases  being  a  metallic 
phosphide.  It  acts  in  a  similar  manner  on  dry  nitrate  of  silver  or  proto- 
nitrate  of  palladium,  whereas  dry  protonitrate  of  mercury  or  chloride  of 
gold  are  not  decomposed  by  it.  (Bottger,  Beitrdge,  2,  ]  16.) 

1 0.  Many  metallic  chlorides  when  gently  heated  in  phosphuretted  hydro- 
gen gas,  produce  hydrochloric  acid  gas — the  volume  of  which  is  three  times 
as  great  as  that  of  the  phosphuretted  hydrogen — and  a  metallic  phosphide; 
or  else  hydrochloric  acid,  free  phosphorus,  and  free  metal.  The  spontane- 
ously inflammable  gas  decomposes  tne  chlorides  of  iron,  cobalt,  nickel,  and 
copper,  and  likewise  chloride  of  chromium,  when  a  stronger  heat  is  applied. 
(H.  Rose.)  Corrosive  sublimate  (HgCl)  heated  in  either  the  more 
inflammable  or  the  less  inflammable  gas  till  it  sublimes,  produces  a  vio- 
lent action,  and  yields  3  measures  of  hydrochloric  acid  gas  together  with 
a  yellowish-red  powder;  with  the  more  inflammable  gas,  a  slight  action 
takes  place  even  in  the  cold.  (Dumas.)  With  solution  of  corrosive  sub- 
limate, both  varieties  of  phosphuretted  hydrogen  give  a  yellow  precipi- 
tate consisting  of  phosphide  and  chloride  of  mercury.  (H.  Rose.) 

11.  With  chloride  of  phosphorus,  phosphuretted  hydrogen  yields 
hydrochloric  acid  and  phosphorus. 

Ccmhinations.  a.  With  water. — Water  freed  from  air  by  boiling  ab- 
sorbs^ according  to  Gengembre,  -^  of  its  volume,  according  to  W.  Henry 


144  PHOSPHORUS. 

^,  according  to  Sir  H.  Davy,  -^^  according  to  Dalton  I,  according  to 
Raymond  ^  of  its  volume  of  the  more  inflammable, — and,  according  to 
Sir  H.  Davy  |  of  its  volume  of  the  les8  inflammable  gas.  Water  thus 
charged  smells  like  the  gas :  its  taste  is  harsh,  faint,  and  disagreeable, 
according  to  Raymond,  and  excessively  bitter,  according  to  Thomson.  When 
boiled,  it  evolves  the  dissolved  gas  in  its  original  state.  It  does  not  shine 
in  the  dark.  When  exposed  to  air  (and  perhaps  also  to  light)  it  evolves 
hydrogen  gas  and  deposits  phosphoric  oxide.  It  does  not  precipitate 
salts  of  manganese,  zinc,  or  iron,  but  gives  precipitates  with  salts  of  lead, 
copper,  mercury,  silver,  and  gold. 

O^ier  Compounds,  a.  With  oil  of  vitriol. — h.  With  hydriodic  acid.— 
c.  With  hydro-bromic  acid. — d.  With  aqueous  solution  of  ammonia? — 
e.  With  several  metallic  chlorides;  e.  g.  APCP,  TiCl»,SnCP,  SbCl».  The 
compounds  of  phosphuretted  hydrogen  with  hydriodic  acid  and  metallic 
chlorides  are  analogous  to  those  of  ammonia :  it  is  immaterial  whether  the 
more  inflammable  or  the  less  inflammable  gas  is  used  in  their  preparation. 
(H.  Rose.)—/.  Phosphuretted  hydrogen  is  absorbed  by  alcohol,  ether, 
and  volatile  oils. 

The  difference  of  inflammability  of  the  two  varieties  of  phosphuretted 
hydrogen  gas  has  been  explained  in  three  different  ways. 

1 .  The  more  inflammable  gas  contains — setting  apart  the  free  hydrogen, 
which  is  always  mixed  with  it,  and  remains  behind  when  the  gas  is  agi- 
tated with  solution  of  sulphate  of  copper — a  larger  quantity  of  phosphorus 
than  the  less  inflammable.  For  this  reason,  the  former  has  been  called 
PerpkosphuretUd  Hydrogen  gas  {Phosphorwasserstof-gas  im  Maximum) ; 
the  latter,  ProtophosphureUed  Hydrogen  gas,  PhosphorwasserstoJ^-gas  im 
Minimum),  This  "view  appeared  to  be  confirmed  by  Dumas, — according  to 
whose  analyses,  the  former  gas  contains  2  atoms, — the  latter,  3  atoms 
of  hydrogen  combined  with  one  atom  of  phosphorus  (see  Dumas'  analyses, 
p.  140).  According  to  Dumas,  the  more  inflammable  gas,  when  kept  for 
some  weeks  under  water  in  a  well-stopped  bottle,  is  converted,  with  de- 
position of  phosphorus,  into  an  equal  volume  of  the  less  inflammable;  it 
likewise  undergoes  the  same  alteration  when  heated  with  alcohol. 
Leverrier  s  view  is  closely  related  to  this.  According  to  him,  the  more 
inflammable  gas  is  a  mixture  of  the  less  inflammable  gas,  PH^  with  more 
or  less  of  the  compound  PH,  or  more  probably  PH^  The  latter,  when 
submitted  over  water  to  the  action  of  light,  is  resolved  into  PH,  which 
is  precipitated  (p.  135),  and  PH»,  (2PH*  =  PH  +  PH');  so  that  the  less 
inflammable  PH'  is  left  in  the  pure  state,  and  exposure  to  sunshine  oc- 
casions no  further  deposit.  These  conclusions,  Leverrier  draws  from  the 
following  experiments.  The  ^as  obtained  by  very  gently  heating  a 
mixture  of  phosphorus  and  milk  of  lime,  deposits  nothing  when  kept  in 
the  dark  in  a  vessel  of  thin  glass  over  well-boiled  water, — ^but  retains 
its  spontaneous  inflammability.  By  exposure  to  daylight,  however,  the 
water  in  the  course  of  two  hours  acquires  a  yellow  colour,  from 
decomposition  of  the  absorbed  gas  and  deposition  of  PH  ;  upon  this, 
the  rest  of  the  gas  deposits  PH — the  more  quickly  in  proportion  to  the 
strength  of  the  light — ^and  is  thereby  converted  into  the  less  inflammable 
gas.  If  the  vessel  is  made  of  thick  glass,  the  gas  retains  its  spontaneous 
inflammability  in  weak  daylight  for  three  months  in  the  winter;  but 
in  the  brighter  daylight  of  May,  it  is  completely  decomposed.  When 
exposed  to  the  sun's  rays  over  water,  the  gas  loses  its  spontaneous  inflam- 
mability in  two  or  three  hours,  and  after  six  or  eight  hours,  no  longer 


PHOSPHURETTED  IIYDROGKiV.  145 

fonns  a  cloud  when  it  escapes  into  the  air.  The  decomposition  is  ac- 
celerated by  frequently  washing  off  the  yellow  film  with  which  the  sides 
of  the  vessel  become  coated.  The  weight  of  the  deposited  PH  amounte 
to  about  -yV  of  the  whole;  consequently,  that  of  the  PH^,  from  which  it 
is  probably  formed,  must  be  about  ^V  ^^  ^^^  S^^  employed.  The  spon- 
taneously inflammable  gas  when  perfectly  dry  remains  quite  unaltered 
in  daylight;  and  even  when  it  is  exposed  to  full  sunshine  in  the  month 
of  June,  no  alteration  takes  place  for  60  hours;  but  by  longer  exposure, 
a  partial  decomposition  is  produced,  by  which  the  gas  loses  indeed  its 
spontaneous  inflammability,  but  produces  white  fumes  when  exposed  to 
the  air,  and  continues  to  deposit  PH  when  exposed  to  light  over  water. 
It  appears  then  that  the  resolution  of  PH'  into  PH  and  PH^  is  very  much 
favoured  by  water.  Water  containing  air  slowly  oxidizes,  in  the  dark,  a 
portion  of  the  PH  of  the  absorbed  gas,  and  precipitates  the  rest ;  but  its 
action  is  slower  than  that  of  light.  (Leverrier.) 

With  these  observations  the  following  older  experiments  are  in  ac- 
cordance. The  spontaneously  inflammable  gas,  when  exposed  to  sun- 
shine, deposits  a  red  phosphoric  substance.  (A.  Vogel.)  It  likewise  de- 
posits phosphorus  when  standing  over  water  (containing  air?)  in  the 
dark,  especially  on  cooling,  and  subsequently  does  not  take  fire  in  the 
air  at  ordinary  temperatures,  excepting  when  brought  in  contact  with 
the  air  in  large  quantity  at  once.  (Vauquelin.) 

2.  According  to  H.  Rose,  both  gases  have  the  same  composition, 
PH';  so  that  their  difference  of  inflammability  must  be  attributed  to 
isomeric  conditions.  It  is  true  that  the  gas  obtained  by  heating  the 
aqueous  solution  of  an  alkali  with  phosphorus  contains  a  larger  quantity 
of  phosphorus; — but  that  substance  is  present  in  the  state  of  vapour 
only,  perhaps  existing  as  PH,  and  is  deposited  in  the  gas-delivery  tube. 
If  the  gas,  as  it  is  evolved,  is  made  to  pass  through  a  receiver  and  a  long 
glass  tube  filled  with  chloride  of  calcium,  care  oeing  taken  to  prevent 
explosion, — it  deposits  the  excess  of  phosphorus  (or  perhaps  PH) ;  and 
if  the  gas  thus  obtained  be  collected  in  bottles  which  are  filled  either 
with  mercury  or  with  water  deprived  of  air  by  boiling,  then  closely 
sealed,  and  exposed  for  two  years  even  to  the  brightest  sunshine,  ifc  de- 
posits no  more  phosphorus,  but  retains  its  spontaneous  inflammability. 
When  phosphorus  is  heated  in  the  less  inflammable  gas  till  it  is  converted 
into  vapour,  the  gas  shows  no  symptom  of  conversion  into  the  spon- 
taneously inflammable  variety.  But  when  kept  for  a  long  time  over 
mercury  at  the  ordinary  atmospheric  pressure,  it  sometimes  acquires 
spontaneous  inflammability.  Moreover,  according  to  H.  Rose's  analyses, 
the  more  inflammable  gas,  when  freed  from  vapour  of  phosphorus,  has  the 
same  specific  gravity  and  the  same  composition,  PH',  as  the  less  inflam- 
mable. The  two  gases  likewise  form  with  hydriodic  acid  and  metallic 
chlorides,  compounds  having  the  same  composition  and  the  same  pro- 
perties; and  these  may  be  made  to  yield  either  the  more  or  the  less 
inflammable  gas,  according  to  the  manner  in  which  they  are  decomposed. 
Whether  a  metallic  chloride  be  in  combination  with  the  more  inflammable 
or  the  less  inflammable  gas,  the  former  gas  is  always  disengaged  from  the 
compound  by  the  action  of  ammonia,  and  the  latter  by  other  liquids. 
(H.  Rose.) 

If  this  view  is  to  be  adopted,  isomerism  must  not  be  understood  in 
the  narrow  sense  to  which  it  is  usually  restricted  (see  I.,  108);  inasmuch 
as  compounds  which  are  isomeric  in  that  sense  exhibit  differences  in  their 
combinations  with  other  bodies,  and  in  their  other  chemical  relations — 

VOL.    II.  L 


146  PHOSPHORUS. 

which  ie  not  the  case  with  the  two  forms  of  phosphuretted  hydrogen.  It 
is  perhaps  rather  to  be  supposed  that  these  gases  exhibit  dimorphous 
relations,  and  that  if  they  conld  be  redaced  to  the  solid  state,  thej 
would  assume  different  crystalline  forms.  This  hypothesis  appears  to 
receiTO  some  support  from  the  analogous  case  observed  by  Frankenheim 
(I.,  100),  viz.  that  the  vapour  of  red  iodide  of  mercury  appears  to  be 
different  in  its  characters  from  that  of  the  yellow  iodide. 

3.  Graham  founds  his  views  on  the  fact  demonstrated  by  Rose — 
that  the  two  gases  have  the  same  composition,  PH' ;  but  he  explains  their 
difference  of  inflammability,  not  by  the  existence  of  two  Isomeric  states, 
but  by  the  admixture  of  foreign  substances.  He  finds  that  perfectly  pure 
phosphuretted  hydrogen  gas  is  not  spontaneously  inflammable;  but  that 
traces  of  foreign  bodies  may  give  it  spontaneous  inflammability,  and 
others  again  may  deprive  it  of  this  property.  Graham's  experiments 
were  made  with  spontaneously  inflammable  gas  prepared  by  heating  milk 
of  litne  with  phosphorus,  and  with  the  less  inflammable  gas  obtained  by 
heating  hydrated  phosphorous  acid. 

a.  The  less  inflammable  may  be  converted  into  the  more  inflammable 
gas  by  admixture  of  a  trace  of  nitrous  acid  vapour,  in  the  following  ways. 
1.  A  small  glass  bulb  filled  with  nitrous  acid  is  introduced  into  the  less 
inflammable  gas  over  mercury:  the  acid  evaporates,  forming  a  small 
white  cloud.  The  mixture  thus  obtained  is  not  itself  spontaneously 
inflammable,  because  it  contains  too  large  a  quantity  of  nitrous  acid ;  but 
it  will  impart  spontaneous  inflammability  to  large  quantities  of  the  less 
inflammable  gas.  One  volume  of  nitrous  acid  vapour  is  sufllcient  to  con- 
vert from  1000  to  10,000  volumes  of  the  less  inflammable  gas  into  the 
more  inflammable. — 2.  A  drop  of  concentrated  nitric  acid  is  introduced 
into  the  gas  as  it  stands  over  mercury ;  the  acid  by  its  action  on  the 
mercury  produces  nitrous  acid. — 3.  The  less  inflammable  gas  is  passed 
through  a  mixture  of  one  measure  of  English  oil  of  vitriol  (which  gene- 
rally contains  a  little  nitrous  acid)  and  3  measures  of  water  immediately 
after  cooling,  and  before  the  nitrous  acid  contained  in  it  has  had  time  to 
escape  into  the  air. — 4.  Pure  hydrogen  gas  mixed  with  the  less  inflam- 
mable phosphuretted  hydrogen  does  not,  as  already  shown  by  Rose,  make 
it  spontaneously  inflammable.  But  if  the  hydrogen  gas  contains  a  trace 
of  nitrous  acid,  it  possesses  this  property.  Such  hydrogen  gas  is  obtained 
by  dissolving  zinc  or  iron  in  a  mixture  of  water  and  common  oil  of  vi- 
triol containing  nitrons  acid ; — it  is  only  the  first  portions  of  gas  evolved 
that  contain  nitrous  acid,  and  are  consequently  eflicacious  in  this  respect. 
One  measure  of  hydrogen  thus  charged  with  nitrous  acid  imparts  spon- 
taneous inflammability  to  between  ^  vol.  and  1  vol.  of  the  less  inflam- 
mable gas.  The  same  result  is  obtained  by  passing  pure  hydrogen  gas 
through  a  mixture  of  one  measure  of  common  oil  of  vitriol  and  3  measures 
of  water,  immediately  after  cooling, — or  by  placing  hydrogen  gas  in 
contact  with  a  freshly  prepared  mixture  of  fuming  nitric  acid  and  water. 
Pure  nitric  oxide  gas  freed  by  washing  with  caustic  potash  from  vapours 
of  nitrous  acid  does  not,  in  any  proportion,  communicate  spontaneous 
inflammability  to  the  less  inflammable  gas;  but  one  volume  of  unwashed 
nitric  oxide  gas  forms — in  consequence  of  the  nitrous  acid  which  is  mixed 
with  it — a  spontaneously  inflammable  mixture  with  1000  to  2000  volumes 
of  the  less  inflammable  gas ;  but  when  the  proportion  of  nitric  oxide  is 
greater  than  ysVt  ^r  less  than  tbWj  ^^^s  effect  is  not  produced. 

The  gas  which  has  acquired  spontaneous  inflammability  by  mixture 
with  nitrons  acid  loses  this  property  in  a  week  when  left  standing  over 


1»H0SPHURETTBD  HYDROGBN.  147 

mtrcniy  (whicli  decomposes  the  nitrous  acid);  orer  water,  a  longer  time 
18  required.  The  power  of  taking  fire  spontaneously  is  quickly  lost  by 
contact  with  potassium-amalgam,  phosphorous  acid,  oil  of  vitriol  (whicn 
probably  absorbs  the  nitrous  acid),  charcoal,  and  Tolatile  oils,  slowly  in 
contact  with  solution  of  potassa,  not  at  all  by  contact  with  phosphoric 
acid. 

b.  The  more  inflammable  gas  loses  its  spontaneous  inflammability 
under  the  following  circumstances  :  1.  When  kept  over  water  containing 
air,  the  change  not  being  attended  with  deposition  of  phosphorus; 
or,  when  mixed  with  a  very  small  quantity  of  air, — the  presence  of  cork 
or  gypsum,  which  contain  air  in  their  pores,  being  sufiicient  to  efiect  the 
change. — 2.  The  admixture  of  about  5  volumes  of  hydrogen,  2  of  car- 
bonic acid,  1  of  defiant  gas,  ^  a  volume  of  hydrosulphuric  acid,  j-  of 
ammoniacal  gas,  ^  of  nitric  oxide,  or  -^  of  hydrochloric  acid  gas,  with 
one  volume  of  the  more  inflammable  gas,  destroys  its  spontaneous  inflam- 
mability. The  gas  mixed  with  -^  of  nitric  oxide  gives  red  vapours  in 
the  air;  that  mixed  with  -^^  of  its  volume  of  the  same  gas  takes  fire  with 
a  kind  of  detonation,  while  the  bubble  is  rising  in  the  air. — 3.  Concen- 
trated phosphoric,  sulphuric,  or  arsenic  acid,  when  the  sides  of  the  con- 
taining vessel  are  moistened  with  them,  destroy  the  spontaneous  inflam- 
mability of  the  gas  in  two  or  three  minutes,  the  change  being  attended 
with  partial  mutual  decomposition ;  arsenious  acid  and  mercurous  oxide 
act  quickly;  solution  of  potash  not  till  after  some  hours. — 4.  Potassium,  by 
itself,  or  even  a  solution  of  1  grain  of  it  in  50  lbs.  of  mercury  (the  sua 
standing  over  it),  destroys  the  spontaneous  inflammability  in  a  few 
minutes. — 5.  One  volume  of  charcoal  cooled  by  plunging  it  when  red- 
hot  into  mercury,  and  then  introduced  into  500  measures  of  the  more 
inflammable  gas,  abeorbs  10  volumes  of  it  in  five  minutes,  and  brings  the 
rest  to  the  less  inflammable  state  in  half  an  hour,  probably  by  absorbing 
the  peculiar  principle  which  causes  the  spontaneous  inflammability.  The 
charcoal  when  heated,  evolves  the  less  inflammable  gas.  In  50  volumes 
of  gafi  the  action  of  1  volume  of  charcoal  is  complete  in  five  minutes. 
Burnt  clay  exerts  a  similar  action.  On  the  contrary,  charcoal  quenched 
in  water,  as  also  spongy  platinum,  red  oxide  of  mercury,  and  solution  of 
proto-sulphate  of  iron,  do  not  remove  the  spontaneous  inflammability. 

After  ail,  the  spontaneously  inflammable  gas  must  contain  a  peculiar 
substance  which  p^ives  it  this  character :  this  substance  cannot  be  nitrous 
acid ;  it  is  probably  a  lower  degree  of  oxidation  of  phosphorus.  (So  ha 
Graham.) 

When  the  spontaneously  inflammable  gas  contained  in  a  glass  tube 
over  mercury  is  strongly  heated  by  means  of  charcoal,  it  does  not  deposit 
phosphorus,  but  loses  its  spontaneous  inflammability.  (A.  Vogel,  /.  pn 
Chem.  6,  348.) 

IF  Paul  Thenard  has  shown  that  the  more  inflammable  phosphuretted 
hydrogen  owes  its  spontaneous  inflammability  to  the  presence  of  a  small 
quantity  of  a  liquid  phosphide  of  hydrogen,  PH',  to  be  described  immedi- 
ately. By  exposure  to  light,  or  by  the  presence  of  hydrochloric  acid 
and  certain  volatile  chlorides,  this  liquid  phosphide  is  resolved  into  the 
solid  phosphide,  which  is  deposited  as  a  yellow  powder,  and  gaseous 
phosphuretted  hydrogen.  The  gas  then  loses  its  spontaueous  inflamma- 
oility.  Phosphuretted  hydrogen  gas  PH',  when  perfectly  pure,  is  not 
spontaneously  inflammable  at  ordinary  temperatures :  it  may  be  obtained 
in  a  state  of  purity  by  the  action  of  strong  fuming  hydrochloric  acid  on 

L  2 


148  PHOSPHOKtJS. 

phosphide  of  calcium,  a  considerable  qoantity  of  tho  solid  phosphide  being 
formed  at  the  same  time. 

Rose  observes — in  confirmation  of  his  idea,  that  the  two  varieties  of 
phosphuretted  hydrogen  are  isomeric — that  they  form  identical  compounds 
with  certain  metallic  chlorides,  and  that,  accordingly  as  these  compounds 
are  decomposed  by  water  or  by  an  ammoniacal  liquid,  the  gas  evolved 
belongs  to  the  less  inflammable  or  the  more  inflammable  variety.  Thenard, 
however,  has  shown  that  when  the  compound  of  phosphuretted  hydrogen 
with  bichloride  of  tin  or  of  titanium  is  decomposed  by  an  ammoniacal 
liquid,  a  rise  of  temperature  is  produced,  whereby  the  gas  is  heated  above 
100°,  and  consequently  takes  fire  as  it  escapes  into  the  air.  If  the  tube 
containing  the  gas  be  artificially  cooled,  this  effect  does  not  take  place. 
(Paul  Th6nard,  N,  Ann,  Chim.  Phys.  14,  5.) 

C.     Liquid  PnospniDB  of  Hydrogen.    PH*. 

Formation.  (1.)  By  the  mutual  action  of  water  and  the  so-called 
Phosphide  of  Calcium,  This  latter  snbstance,  which  is  obtained  by  the 
action  of  vapour  of  phosphorus  upon  lime  at  a  red-heat,  has  been  shown 
by  Paul  Thenard  to  be  a  mixture  of  phosphide  of  calcium  and  phosphate 
of  lime :  2  (PO*,  2CaO)  +  5PCa».  When  it  is  put  into  water,  the  5  atoms 
of  phosphide  of  calcium,  PCa^  and  10  atoms  of  water,  produce  10  atoms 
of  lime  and  5  atoms  of  liquid  phosphide  of  hydrogen : 

5PCa«  +  lOHO  =  lOCaO  +  5PH«. 

(2.)  By  deposition  from  spontaneously  inflammable  phosphuretted  hydro- 
gen gas. 

Preparation.  Into  the  middle  tubulure  of  a  three-necked  Woulfe's 
bottle,  holding  about  a  pint,  is  inserted  a  glass  tube  12  inches  long  and 
half  an  inch  wide,  so  as  to  reach  nearly  to  the  bottom.  To  the  second 
tubulure  is  adapted  a  tube  twice  bent  at  right  angles;  this  tube  dips  into 
water  and  serves  for  a  safety-tube.  Into  the  third  is  fitted  a  tube  of  ^ 
inch  diameter,  which  serves  first  for  a  condenser  and  then  for  a  receiver; 
it  is  bent  ^-shape,  so  that  it  may  be  immersed  to  the  depth  of  5  or  6 
inches  in  a  freezing  mixture.  The  part  which  projects  above  the  freezing 
mixture  is  bent  at  a  not  very  acute  angle,  and  drawn  out  at  two  points 
not  far  from  each  other  and  near  the  end,  so  that,  at  the  conclusion  of  the 
operation,  the  liquid  may  be  introduced  into  the  intermediate  part  of  the 
tube,  and  the  parts  which  have  been  drawn  out  closed  by  the  blowpipe. 
The  apparatus  being  thus  arranged,  the  bottle  is  three  parts  filled  with 
water  and  placed  in  a  water-bath  heated  to  between  140°  and  160°  F. 
The  last-mentioned  tube  is  closed,  and  a  few  drops  of  phosphide  of  calcium 
thrown  through  the  middle  one  into  the  bottle.  The  gas  evolved  takes 
fire,  and  drives  out  the  air  through  the  safety-tube.  The  ^-shaped  tube 
is  now  to  bo  opened,  and  from  400  to  600  grains  of  phosphide  of  calcium 
gradually  introduced  into  the  bottle:  in  a  few  minutes,  oily  d]*ops  of 
liquid  are  seen  to  collect  in  the  part  of  the  tube  nearest  to  the  bottle. 
The  process  must  be  stopped  after  15  or  20  minutes,  because  water  con- 
denses in  the  tube  together  with  the  phosphide  of  hydrogen,  and  often 
stops  it  up.  The  tube  is  now  to  be  sealed  at  the  narrowed  neck  nearest  to 
its  extremity,  then  removed  from  the  bottle,  and  held  by  the  finger 
(covered  with  caoutchouc  to  save  the  operator  from  being  burnt)  in  such 
a  position  that  any  remaining  gas  may  escape;  it  is  then  warmed  by  the 


LIQUID  PHOSPHIDE   OF  HYDROGEN.  149 

band  to  canse  the  portions  of  liquid  which  have  been  separated  by  par- 
ticles of  ice  to  ran  together,  and  again  placed  in  the  freezing  mixture  to 
solidify  the  water,  and  prevent  it  running  back.  This  being  effected, 
the  liquid  is  made  to  flow  towards  the  sealed  end  of  the  tube,  and  the 
other  neck  of  the  tube  closed  by  the  blowpipe.  A  well-conducted  opera- 
tion yields  about  30  grains  of  liquid. 

Properties.  Colourless  liquid,  not  solidifying  at — 20°  C;  at  30°  or  40°, 
it  appears  to  volatilize  and  to  be  decomposed  at  the  same  time.  Refracts 
light  strongly.  Insoluble  in  water.  Alcohol  and  oil  of  turpentine  appear 
to  dissolve  it,  but  it  quickly  decomposes  in  the  solution.  Bums  in  the 
air  with  an  intensely  bright  white  flame,  and  produces  dense  white  fumes. 
Communicates  spontaneous  inflammability  to  500  times  its  weight  of  the 
less  inflammable  phosphuretted  hydrogen  gas,  the  latter  thereby  acquiring 
all  the  properties  of  the  more  inflammable  gas.  All  combustible  gases 
are  renaered  spontaneously  inflammable  by  admixture  with  liquid  phos- 
phide of  hydrogen. 

The  composition  of  this  substance  is 

By  Calculation. 

P    31-7  94-07 

2H    2'0  5-93 

PH^     33-7     lOOCO 

DecomposUioTis.  By  the  action  of  light  it  is  resolved  into  solid  (PH) 
and  gaseous  phosphide  of  hydrogen  (PH'): 

5PH«  =  P'H  +  3PH». 

It  is  also  decomposed,  like  peroxide  of  hydrogen,  by  contact  with  various 
substances.  An  indefinite  quantity  of  liquid  phosphide  of  hydrogen  may 
be  decomposed  by  a  cubic  centimetre  of  hydrochlonc  acid  gas.  IT 

Phosphorus  and  Carbon. 

Phosphide  of  Carbon?  This  compound  is  obtained,  according  to 
Thomson  (Ann,  Phil.  8,  157),  when  phosphide  of  calcium  is  decomposed 
by  water,  and  the  lime  dissolved  out  by  excess  of  hydrochloric  acid; 
phosphide  of  carbon  then  remains  behind,  and  must  be  collected  on  a 
filter  and  quickly  washed.  It  is  a  brownish-yellow,  soft,  tasteless, 
inodorous,  and  infusible  powder.  According  to  Thomson,  it  contains 
38  carbon  -h  62  phosphorus.  It  suffers  no  alteration  in  dry  air  below 
100"^,  but  takes  fire  at  a  red  heat,  the  phosphorus  burniug  to  phosphoric 
acid,  while  the  carbon  remains  unburnt.  It  attracts  water  from  the  air, 
forming  carburetted  hydrogen  gas  and  carbonic  acid.  (Thomson^  It 
is  probably  a  mixture  of  phosphoric  oxide  and  charcoal,  which  latter 
substance  is  perhaps  separated  from  carbonic  acid  remaining  in  the  lime. 

A  similar  substance  remains  behind  when  the  crude  phosphorus 
obtained  by  the  distillation  of  calcareous  phosphoric  acid  is  pressed  through 
chamois  leather  (p.  104).  When  the  free  phosphorus  is  separated 
from  this  substance  by  distillation,  and  the  orange-jrellow  residue  is 
heated  to  redness  (at  which  temperature  the  phosphoric  oxide  is  decom- 
posed), it  evolves  phosphorus  and  leaves  charcoal  behind.  (Berzelius, 
Lehrh.  1,  312.) 

Phosphuretted  Carbonic  oxide  gas?  When  phosphorus  is  prepared  by 
distilling  phosphoric  acid  with  charcoal  (p.  104),  the  whole  of  the  phos- 


150  PHOSPHORUS. 

phorus  does  not  condense  in  the  receiver,  bnt  a  portion  remains  dissolved 
in  tbe  gas  which  is  evolyed.  This,  when  freed  from  carbonic  acid  by 
agitation  with  milk  of  lime,  is  of  about  the  same  specific  gravity  as 
common  air — has  a  disagreeable  odour — does  not  redden  litmus— -does 
not  deposit  phosphorus,  even  after  long  standing — exhibits  no  luminosity 
when  brought  in  contact  with  oxygen  gas — bums  with  that  gas  at  aa 
elevated  temperature  with  less  forcible  explosion  than  hydrogen,  and  with 
a  white  flame,  producing  phosphoric  acid,  carbonic  acid,  and  water.  It 
reduces  gold  and  silver  from  their  solutions  in  acids.  Trommsdorff 
(A.  Tr.  10,  1,  30),  who  first  distinguished  this  gas,  regards  it  as  a  com- 
pound of  phosphorus,  carbon,  and  hydrogen,  and  calls  it  Fhosphuretled 
CarburetUd  Hydrogen  gas.  It  is  probably  a  mixture  of  carbonic  oxide, 
hydrogen^  and  phosphuretted  hydrogen. 


Phosphorus  with  Phosphorus. 
Phosphate  of  Phosphoric  Oxide,  or  Phosphoric  Phosphate. 

The  yellow  film  of  phosphoric  phosphate,  which  is  produced  in  the 
preparation  of  phosphoric  oxide  by  the  fifth  method  (p.  ill),  is  freed 
from  adhering  phosphorous  acid  and  hydrochloric  acid,  by  washing  it  in 
the  flask  in  which  it  has  been  deposited — first,  with  ether,  which  removes 
the  greater  portion  of  the  free  acids,  and  then  with  absolute  alcohol, 
which  dissolves  the  rest  of  the  free  acids,  together  with  the  phosphoric 
phosphate  and  a  small  quantity  of  phosphorus.  The  liquid  filtered  from 
the  undissolved  phosphorus  is  mixed  with  absolute  ether,  which  retains 
in  solution  the  phosphorus  and  the  free  phosphoric,  phosphorous,  and 
hydrochloric,  acids,  but  precipitates  the  phosphoric  phosphate.  This 
precipitate  is  washed  with  ether,  and — in  order  to  purify  it  completely — 
again  dissolved  in  alcohol  and  precipitated  by  ether,  it  is  then  put  into 
a  dish — the  greater  part  of  the  ether  removed  by  means  of  a  pipette — 
and  the  rest  left  to  evaporate  in  vacuo  over  oil  of  vitriol.  The  phos- 
phoric phosphate  remains  behind,  mixed  with  a  small  quantity  of  organic 
matter  from  the  ether,  wliich  cannot  be  removed. 

This  substance  is  of  an  orange-yellow  colour,  easily  pulverized, 
inodorous,  and  has  a  very  faint  taste. 

Its  composition  is  about  4P*0,  3P0* 

It  resolves  itself  spontaneously,  after  a  time,  into  phosphoric  acid  and 
phosphoric  oxide.  When  newly  prepared,  it  is  completely  soluble  in 
water;  but  the  yellow  solution  deposits  hydrated  phosphoric  oxide,  after 
a  few  hours  at  ordinary  temperatures,  and  immediately  at  SO''.  The  still 
undecomposed  aqueous  solution  is  coloured  deep  brown,  without  precipi- 
tation, by  caustic  potassa,  possibly  from  formation  of  a  double  phosphate 
of  potassa  and  phosphoric  oxide ;  but  on  the  application  of  heat,  phos- 
phoric acid  is  precipitated  in  combination  with  a  certain  portion  of 
potassa.  Alcohol  completely  dissolves  freshly  prepared  phosphoric 
phosphate,  forming  a  yellow  solution.  (Leverrier,  Ann»  CMm,  Pkys. 
65,257.) 

Other  Compounds  op  Phosphorus. 

A.  With  sulphur.— B.  With  selenium.— C.  "With  iodine.— D.  With 
bromine. — E.  With  chlorine. — G.  With  nitrogen. 

H.  With   most  metals,  forming  compounds    called   Phosphides    or 


SULPHUR.  ]51 

Phosphurets,  The  affinity  of  phosphorus  for  metals  is  not  so  strong  as 
that  of  sulphur.  Metallic  phosphides  are  formed :  1 .  Bj  bringing  the 
phosphorus  and  the  metal  together  at  elevated  temperatures,  the  combi- 
nation being  often  attended  with  development  of  light  and  heat. — 2.  By 
igniting  the  metal  in  contact  with  phosphoric  acid,  either  pure  or  con- 
taining lime,  and  either  with  or  without  charcoal,  the  charcoal  or  a 
portion  of  the  metal  taking  up  the  oxygen  of  the  phosphoric  acid.  3. 
By  heating  certain  metallic  oxides  in  contact  with  phosphorus;  part  of 
the  phosphorus  then  combines  with  the  oxygen  to  form  phosphoric  acid,— • 
the  rest  with  the  metal,  to  form  a  metallic  phosphide. — 4.  By  igniting  a 
metallic  phosphate  with  charcoal. — 5.  By  bringing  phosphuretted  hydro- 
gen in  contact  with  metallic  chlorides,  oxides,  and  their  salts. 

The  metallic  phosphides  are  solid  and  almost  all  brittle;  they  gene- 
rally exhibit  the  metallic  lustre,  and  are  opaque.  At  very  high  tempe- 
ratures, many  metals  give  up  their  phosphorus.  In  some  phosphides,  the 
phosphorus  alone  oxidates  in  the  air  at  ordinary  temperatures — in  others, 
the  metal  likewise  oxidates.  At  high  temperatures,  combustion  of  the 
phosphorus  always  takes  place,  sometimes  attended  with  the  formation 
of  the  corresponding  phosphate.  Nitric  or  hypochlorous  acid  converts  the 
phosphides  into  phosphates.  The  compounds  of  phosphorus  with  the 
alkali-metals  decompose  water,  producing  phosphuretted  hydrogen  gas, 
hypophosphorous  acid,  and  a  metallic  oxide. 

I.  With  alcohol,  ether,  volatile,  and  fixed  oils,  wax,  and  resins. 


Chapter  VI. 

SULPHUR. 


Sulphur  in  general : 

H.  Davy.  PhU.  Trans.  1809,  I.,  59;  Schw.  1,  473,  484,  also  Gilh.  35, 
278;  36,  184.     Further,  Schw.  7,  508;  also  GUb.  36,  184. 

Qay-Lussac  &  Th^nard.  Pecherches,  1,  187;  also  Ann.  Ckim.  Phif§.  78, 
229;  also  Schw.  1,  488;  also  GUb.  35,  292. 

Dumas.     Ann.  Chim.  Phys.  36,  83;  also  N.  Tr.  17,  1,  197. 

Marchand  &  T.  Scheerer.    J.  pr.  Chem.  24,  129. 

Hyposulphurout  add: 

Oay-Lussac.     Ann.  Chim,  85,  199. 

Herschel.     Ed.  Phil.  J.  1,  8  and  396 ;  2,  154 ;  also  ^.  Tr.  6,  2,  308. 

Keasler.     Pogg.  74,  274;  abstr.  Ann.  Pharm.  68,  231. 

Pentaihionic  add: 

Wackenroder.     Arehiv.  der  Pharm.   47,   272;    48,   140;   abstr.  Ann. 

Pharm.  60,  189. 
Lenoir.     Ann.  Pharm.  62,  253. 
Pordos  k  Gelis.     N.  Ann.  Chim.   Phys.  22,  66;  abstr.  Ann.  Phdrm. 

64,  249. 


152  SULPHUR. 

Kessler.     Fogg.  74,  249;  abstr.  Ann,  Pharm,  68,  231. 

Telrathionic  acid: 

Fordos  &  Gelis.    Compt,  Rend.  15,  920;  Ann.  Pfiarm.  44,  217. 
Kessler.     Pogg,  74,  249. 

Triikionic  acid : 

Langlois.     Compt.  Rend.  10,  461;  also  J.  pr.  Chem.  20,  61. — Further: 

Ann.  Chim.  Pkgs.  79,  77;  also  Ann.  Pharm.  40,  102. 
Pelouze.     Ann.  Chim.  Phy$.  79,  %5. 
Kessler.     Pogg.  74,  249. 

Sulphurous  acid: 

Fourcroy  &  Vauquelin.     Ann.  Chim.  24,  229;  also  Crell.  Ann.  1800,  2, 

299  and  388  (the  end  of  this  memoir  is  wanting). 
Bussj.     J.  Pharm.  10,  202;  also  Ann.  Chim.  Phys,  26,  63;  also  >S^cAt0. 

41,  451 ;  Pogg.  1,  237;  Kastn.  Arch.  2,  127  and  241 ;  Mag.  Pharm. 

7,  160;  Berl.  Jahrh.  26,  2,  45. 
Delarive.     Bibl.  Univ.  40,  196;  also  N.  Tr.  20, 1,  197;  abstr.  Po^^.  15, 

523;  abstr.  Schw.  55,  232. 
Sulphites.     Muspratt.     Ann.  Pharm.  49,  259.     Further :  Phil.  Ma^.  J. 

30,  414.     Rammelsberg.  Pogg.  67,  245. 

Hyposulphuric  acid: 

Welter  &  Gay-Lussac.     Ann.  Chim.  Phys.  10,  312;  also/ScAw.  29,  182; 

also  GiJh.  ^5,  252.     Heeren,  Pogg.  7,  55. 
Rammelsberg.     Pogg.  58,  295;  abstr.  Ann.  Pharm.  48,  207. 

Sulphuric  acid: 

Formation.     Clement  &  Desormes.     Ann.  Chim.  59,  329;  also  N.  Gehl. 

4,  456.     Peligot.  N.  Ann.  Chim.  Phys.  12,  263. 
Anhydrous.     F.  C.  Vogel.  Schw.  4,  121. — Bussy,  Ann.  Chim.  Phys.  26, 

411 ;  also  J.  Pharm.  10,  368;  also  Mag.  Pharm.  8,  69;  also  N.  Tr. 

9,  2,  65.— Wach.  Schw.  50,  1.— H.  Rose.  Pogg.  39, 173.— Barreswil. 

Compt.  Rend.  25,  30. 
Sulphates.     Gay-Lussac.     M^m.  cTArcueil,  1,  215;  also  y.  Gehl.  4,  465; 

also  Gilb.  27,  86.     Further:  Ann.  Chim.  Phys.  63,  431 ;  also  Ann, 

Pharm.  22,  305;  also  J.pr.  Chem.  11,65. — Graham.   Phil.  Mag.  J. 

6,  329.     Ann.  Pharm.  29,  27. 

Persulphide  of  Hydrogen : 

Scheele.  Von  der  Luft  und  von  dem  Fetter,  153. — Berzelius.  Lehrh.  2, 
218. — Th^nard,  Ann.  Chim.  Phys.  48,  79;  also  Schw.  64,  231 ;  also 
Ann.  Pharm.  2,  11;  also  N.  Tr.  25,  2, 198. — Liebig.  Ann.  Pharm. 
2,27;  18,  170. 

Hydrostdphuric  acid: 

Scheele.  Opuscula,  1,  132. — Berthollet.  Scher.  J.  1,  367. — Fourcroy. 
Crell.  Ann.  1793,  2,  64.— A.  Vogel.  J.  Phys.  82,  329.- Bischof. 
Schw.  39,  38. — H.  Rose.  Pogg.  47,  161.— Action  of  Hydrosulphuric 
acid  on  Fish.     Blanchet.  Ann.  Pharm.  53,  109. 


SULPHUR.  158 

Bisulphide  ofCarbmi: 

Lampadius.     A.  Gehl  2,  192. — Clement  &  Desormes.  Ann,  Chim.  42, 

121;  also  Scher,  /.  7,  10,  512;  also  Gilb.  1 3, 73.— Trommsdorff.  A. 

Tr.  17,  1,  29.— Am.  BertboUet.  GiJh.  28,  427.— Vauquelin  &  Robi- 

quet.  Ann,  Ckim,  61,  145;  alsoiV^.  GeJd.  4,  12;  also  GUh,  28,  453.— 

Cluzel.  Ann.  Ckim.   84,  72. — BertboUet,    Thenard   &   Vauquelin. 

Ann,  Chim.  83,  252;  ^XsoSchw.  9,  301. — Berzelius  &  Marcet.  Schw. 

9,  284;  also  Gilb,  48,  135;  Kolbe.  Jwn.  Pharm  45,  41.— Berzelius. 

Gilb.  48,  177;  also /bVAwf.  34,  75.— Zeise.  Sckw.  36,  1;  41,  98  and 

170;   43,   160. — Berzelius.  Pogg,    6,   444. — Conerbe.    Ann.   Chim. 

Phya,  61,  225;  abstr.  J.  pr,  Chem.  23,  83. 
Sulphide  of  Boron,     Berzelius.  Pogg,  2,  125. 
Sulphides  of  Phosphorus,     Marggraf.  Cht/m,  Schrift,   1,   47. — Pelletier. 

Ann.  Chim.  4,  1. — Faraday.  Ann.  Chim,  Phys,  7,  71. — R.  Bottger. 

Schw,  67,  141;  68,  136. — J.pr,  Chem,  12,  357.— Level.  Ann,  Chim. 

Phys,  67,  332;  also  J,  pr,  Chem.  15,  119. — A.  Dupr6.  Ann,  Chim. 

Phys.  73.  435;  abstr.  J,  pr,  Chem,  21,  253. — Berzelius.  Ann.  Pharm.. 

46,  129,  255;  also  TraiU  de  Chimie,  Par.  1845,  I.,  815. 

Metallic  Sulphides- 

Alkaline  Sulphides,  Vauquelin.  Ann.  Chim.  Phys.  6,  5;  also  N.  Tr.  2, 
2,  270.— Tbenard.  Ann.  Chim.  83,  132;  tAso  Gilb.  44,  94.  Gay- 
Lussac.  Ann,  Chim,  7S,  86;  also  6^^1/6.  41, 328 ;  also  ^^cAw^.  24,  234.— 
Ann.  Chim.  Phys.  6,  321;  also  N.  Tr.  3, 1, 195. — Ann.  Chim.  Phys. 
30,  24;  also  iV.  Tr.  12.  2,  195.— Berzelius.  Schw.  34,  1.— Berthier. 
Ann.  Chim.  Phys.  22,  225;  also  iV.  !Pr,  9, 1,  66. — Ann,  Chim.  Phys. 
24,  273;  also  Mag.  Pharm.  5,  284.— H.  Rose.  Pogg,  55,  415. 

If eavy  Metallic  Sulphides  and  Sulphur-salts,  Deiman,  Troostwyk,  Nieuw- 
land,  Bondt,  k  Lauwerenburgh.  Crell,  Ann,  1793,  2,  383.— Arfved- 
son.    Pogg,  1,49;  also  ^.  Tr.  10,  2,144. — Berzelius.   Pogg,  6,425. 


S(y^fre^  Schwefel, 

History.  Sulphur  has  been  known  from  the  earliest  times.  The 
Arabians  were  perhaps  acquainted  with  sulphuric  acid ;  but  Basil  Valen- 
tine is  the  first  who  mentions  its  preparation  from  green  vitriol :  the  for- 
mation of  this  acid  by  the  burning  of  sulphur  was  first  brought  into  use 
in  England  in  the  year  3720.  The  white  substance  obtained  by  distilling 
fuming  oil  of  vitriol,  and  long  known  by  the  nsime  of  Ice-oil  {JSis-ol),  or 
Oleum  gladale  Vitrioli,  was  regarded  by  Dollfuss  (Crell.  Ann,  1785,  1, 
438)  and  Pourcroy  (Crell,  Ann,  1791,  1,  363),  as  concentrated  sulphuric 
acid  combined  with  sulphurous  acid ;  by  Winterl,  as  sulphuric  acid  com- 
bined with  excess  of  oxygen;  by  P.  C.  Vogel,  as  sulphuric  acid  deprived 
of  the  greater  part  of  its  water,  and  combined  with  an  imponderable  ethe- 
real principle;  but  the  experiments  of  Vogel,  as  well  as  those  of  Doberei- 
ner  (Schw.  13,  476),  C.  G.  Gmelin  (Schw,  27,  439),  Ure  (Quart.  J,  ofSc. 
19,  62),  and  Bussy  (J.  Pharm.  10,  368),  established  the  view  already 
put  forth  by  Scheele  (Opusc.  2,  284),  and  Guyton-Morveau  (in  his  Grundy 
satzen  iiber  die  sauren  Sake,  I.,  179),  and  now  universally  admitted,  viz., 
that  this  substance  must  be  regarded  as  anhydrous  sulphuric  acid. — The 
roportional  composition  of  sulphuric  acid  was  examined  principally  by 
ichter,  Klaproth,  Bucholz,  and  Berzelius. — Sulphurous  acid,  the  compound 


I 


154  SULPHUR. 

long  known  to  be  fonned  in  the  combustion  of  salpbur,  was  first  examined 
minutely  by  Stahl;  in  1771  by  Scbeele;  in  1774  by  Priestley,  who  first 
collected  it  as  a  gas  over  mercury;  in  1782  and  1789  by  BerthoUet;  and 
in  1797  by  Fourcroy  &  Vauquelin,  who  made  known  the  properties  of 
many  of  its  salts.  Monge  &  Clouet  first  obtained  sulphurous  acid  in  the 
liquid  state,  in  which  form  it  was  examined  chiefly  by  Faraday,  Bussy^ 
Wach,  and  Delarive. — The  hyposulphites  were  first  examined  by  Vau- 
quelin (Crell.  Ann.  1800,  2,  286),  afterwards  by  Gay-Lussac  and  Her- 
schel. — Welter  and  Gay-Lussac  discovered  hyposulphuric  acid ;  Langlois 
discovered  sulphuretted  hyposulphuric  acid,  otherwise  called  trithionic 
acid;  tetrath ionic  acid  was  discovered  by  Fordos  &  Gelis;  pentathionic 
acid  by  Wackenroder. 

Persulphide  of  hydrogen,  discovered  by  Scheele,  has  been  more  particu- 
larly examined  by  Berzelins,  Thenard,  and  Liebig. — Hydrosulphuric  acid 
was  first  discovered  by  Rouelle,  but  more  minutely  examined  as  to  its 
composition  by  Scheele :  subsequently,  its  chemical  relations  were  further 
investigated,  principally  by  Bergmann,  Kirwan,  Berthollet,  Proust,  The- 
nard, Gay-Lussac,  Berzelius,  and  Sir  Humphry  Davy. 

Bisulphide  of  carbon,  discovered  by  Lampadius  in  1796,  was  by  him 
and  by  Am.  Berthollet  pronounced  to  be  a  compound  of  sulphur  and 
hydrogen,  and  by  Cluzel,  a  compound  of  sulphur  with  carbon,  hydrogen, 
and  nitrogen ;  but  the  experiments  of  C.  L.  Berthollet,  of  Thenard  &  Vau- 
quelin, and  of  Berzelius  &  Marcet,  have  shown  that  it  is  really  composed  of 
sulphur  and  carbon,  as  first  announced  by  Clement  &  Desormes. — ^Zeise  dis- 
covered the  acids  produced  by  treating  bisulphide  of  carbon  with  alkalis  and 
alcohol,  viz.,  the  hydrosulphocarbonic,  hydrosulphocyanic,  and  xanthonio 
acids. 

Berzelius  discovered  sulphide  of  boron.  Sulphide  of  phosphorus,  first 
prepared  by  Marggraf,  was  further  examined  by  Pelletier,  Faraday, 
Mitscherlich,  Bottger,  Level,  and  Dupr6.  The  sulphides  of  phosphorus 
have  subsequently  been  subjected  to  complete  examination  by  Berzelius. 

The  development  of  light  and  heat,  which  frequently  accompanies  the 
combination  of  sulphur  with  metals,  was  long  ago  observed  by  Scheele; 
but  Deiman,  Troostwyk,  Nieuwland,  Bondt  &  Lauwerenburgh  first 
showed  that  this  combustion  takes  place  equally  well  when  air  is  excluded. 
The  nature  of  livers  of  sulphur  was  principally  investigated  by  Vauquelin, 
Gay-Lussac,  and  Berzelius.  The  latter,  moreover,  examined  the  other 
metallic  sulphides  with  the  greatest  accuracy,  and  laid  the  foundation  of 
the  theory  of  the  Sulphur-salts. 

Occurrence  in  nature,  1.  Native.  2.  As  sulphurous  acid.  3.  As 
sulphuric  acid.  4.  As  hydrosulphuric  acid.  5.  In  the  metallic  sulphides. 
6.  In  certain  organic  compounds. 

Preparation,  1,  Native  sulphur  is  separated  by  distillation  from  the 
earthy  matters  with  which  it  is  mixed.  In  Sicily,  the  volcanic  sulphur  is 
distilled  in  large  earthen  pots  provided  with  a  beak  on  the  side. — 2.  From 
iron- pyrites  or  copper-pyrites,  a  portion  of  the  sulphur  is  expelled  by 
heating,  the  process  being  conducted — a.  By  roasting  the  ore  in  heaps 
(Bost-ftaufen),  A  square  surface  is  covered  with  a  few  layers  of  billet- 
wood,  and  upon  this  the  copper-pyrites,  coarsely  pounded,  is  heaped  in  the 
form  of  a  truncated  pyramid.  The  sides  of  this  pjrramid  are  covered  with 
a  layer  of  earthy  matter  to  render  them  impervious  to  draught.  Fire  is 
applied  to  the  wood  by  a  channel  which  passes  downwards  through  the 


SULPHUR.  155 

middle  of  the  p3rTainid ;  thence  it  is  oommnnicated  to  the  ore,  and  gradu- 
ally extends  to  the  whole  mass.  The  sulphur  contained  in  the  ore  is 
partly  burnt  and  converted  into  sulphurous  acid,  partly  rises  in  vapour  to 
the  upper  truncated  surface  of  the  pyramid,  and  there  condenses  in  hollows 
formed  for  the  purpose  and  covered  at  the  bottom  with  smooth  earth. 
From  these  it  is  from  time  to  time  removed.  (Schliiter,  Unier}*ickt  von  Hut- 
tenwerken,  154.) — h.  In  the  roasting  furnace  (Rosidfen).  The  ore  is  piled 
up  upon  wood  between  four  walls  perforated  with  holes  at  the  bottom  ;  it 
is  then  covered  with  earth.  When  the  wood  is  set  on  fire,  the  draught  of 
air  produced  by  side-tubes  opening  into  the  furnace  at  its  upper  part 
carries  the  sulphur  vapour  into  a  condensing  chamber.  (Ferber,  Beitrape, 
gur  MineraJrgeadiichte,  I.,  220.)  If  the  furnace  is  high  and  narrow,  fresh 
ore  may  be  introduced  at  the  top  as  fast  as  that  which  is  burnt  is  taken 
away  at  the  bottom.  In  that  case,  the  covering  is  formed,  not  of  earth, 
but  of  solid  plates,  and  the  roasting  is  carried  on  without  interruption. 
H'hen  once  the  ore  has  been  set  on  fire  by  means  of  wood  or  coal,  the 
combustion  extends  itself  through  the  entire  mass.  {Bergmdnnisches  J. 
3,  1.) — c.  A  number  of  tubes  of  earthenware  or  cast-iron,  called  Sulphur- 
tubes,  are  laid  very  slightly  inclined  to  one  another  in  a  common  furnace. 
(^Schwefel-ireibbfen  oder  Schwefel-brenndfen.)  They  are  filled  with  iron- 
pyrites  through  the  upper  and  wider  opening,  which  is  closed  while  the 
combustion  is  going  on.  From  the  lower  and  narrower  opening  the  sul- 
phur flows  into  a  cast-iron  receiver  (  Vorsetz-Kastchen),  The  protosulphide 
of  iron  {die  SchwrfeUhrande),  which,  after  the  combustion,  is  to  be  taken 
out  by  the  upper  opening,  serves  iPor  the  fabrication  of  green  vitriol. 
(SchlUter,  Unterrickt  von  Hiittenwerken,  37.) 

I^urificcUion.  The  Crude-Sulphur  {Roh-achwefel  or  Treihschwefel) 
obtained  in  this  manner  may  be  mixed  with  earthy  matters  and  particles 
of  the  ore,  and  may  also  contain  sulphide  of  arsenic,  seletaide  of  sul- 
phur, and  asphalt.  It  may  be  purified  as  follows  : — (1.)  Bt/ fusion  and 
decanUUion,  The  sulphur  is  melted  in  a  cast-iron  vessel,  the  coarser 
particles  removed  by  means  of  a  perforated  ladle,  and  the  sulphur  after 
standing  for  some  time,  poured  oft'  from  the  finer  particles  which  have 
fallen  to  the  bottom.  This  mode  of  purification  is  the  least  efi*ective. 
(2.)  By  distillation  in  the  Sulphur-purifying  furnace  (SchwefelldtUer-dfen). 
This,  according  to  the  old  arrangement,  is  a  reverberatory  furnace,  on  the 
two  sides  of  which  a  number  of  cast-iron  vessels,  called  Purifying  vessels 
(Lduter-kruge),  are  placed  on  benches.  They  are  filled  with  crude  sul- 
phur, and  provided  with  an  iron  or  earthenware  head  {Sturz),  the  beak  of 
which  passes  into  a  receiver  placed  outside  the  furnace.  (Schliiter, 
Unterr.  von  JJiittenwerken,  39.)  In  the  new  arrangement  invented  by 
Michel,  the  sulphur  is  heated  to  the  boiling  point  in  a  large  cast-iron 
boiler  over  which  an  arch  of  brickwork  is  raised.  The  vapour  passes 
sideways  through  a  wide  brick  channel  into  a  chamber  likewise  formed 
of  brick-work,  where  it  condenses,  first  in  the  form  of  flowers  of  sulphur; 
but  afterwards,  if  the  process  be  continued  uninterruptedly  night  and  day, 
and  the  temperature  of  the  chamber  thereby  raised  to  the  melting  point  of 
sulphur,  it  collects  at  the  bottom  in  the  fused  state,  and  may  be  drawn  off 
by  an  opening  in  the  side.  (Dictionn,  Technolog,  Paris,  1831,  19,  491.) 
(3.)  By  Sublimation, — This  process  may  likewise  be  conducted  in  Michel's 
apparatus;  only  it  must  be  more  frequently  interrupted,  so  that  the 
chamber  may  not  get  too  hot ;  the  sulphur  collects  on  the  walls  in  the 
state  of  fine  powder. 


156  SULPHUR. 

The  sulphur^  after  being  parifled  by  fusion  or  distillation,  is  cast  in 
damp  wooden  moulds,  sometimes  in  cheese-shaped  masses,  called  Loaves  of 
Sulphur  {Schufefel-brode) ;  sometimes  in  sticks,  in  which  state  it  is  called 
Rolled  Sulphur  {Stangen-sdiwefely  Sulphur  citrinum).  The  sublimed 
sulphur  is  called  Flowers  of  Sulphur  (Schwefel-blumen,,  Flores  Sulphuris) ; 
it  requires  to  be  washed  with  water  to  free  it  from  adhering  sulphurous 
and  sulphuric  acids. 

Sulphur  purified  bj  method  1.  may  still  contain  portions  of  earth  and 
ore ;  and  that  which  is  purified  by  either  of  the  methods  1 , 2,  or  3,  may  retain 
arsenic,  sulphur,  and  bituminous  matters.  (Vauquelin.  Ann,  Ghim.  Pkys, 
25,  50.)  By  repeated  fractional  distillation,  whereby  these  substances, 
being  less  volatile,  are  partially  left  behind,  the  sulphur  becomes  con- 
tinually purer.  According  to  Osann  (Kastn.  Arch.  4,  344),  it  requires 
five  or  six  distillations  to  render  it  sufficiently  pure  to  sublime  without 
leaving  a  carbonaceous  residue. 

Rolled  sulphur,  when  heated  by  itself,  and  flowers  of  sulphur  heated 
in  contact  with  water,  evolve  hydrosulphuric  acid  gas.  (Payen,  J,  Pharm, 
8, 37] .)  Moist  sulphur  evolves  hydrosulphuric  acid  when  heated.  ^Pleischi. 
Kastn,  Arch.  4,  340.)  Sulphur,  when  it  enters  into  combination  with 
metals  (copper,  for  example)  evolves  0-1  per  cent.,  or  a  smaller  quantity,  of 
hydrogen  gas :  but  if  it  has  previously  been  fused  by  itself,  it  evolves  no 
more  than  a  mere  trace  of  that  substance.  (Dumas,  Ann.  Chim,  Phys.  50^ 
176.)  It  appears  from  this  that  sulphur  contains  either  hydrosulphuric 
acid  in  a  state  of  condensation,  or  else  persulphide  of  hydrogen ;  or  again, 
the  hydrogen  may  proceed  from  aephaltum  or  water  contained  in  the 
sulphur. 

The  presence  of  arsenic  in  sulphur  is  detected,  according  to  Berzelius, 
by  digesting  the  sulphur  in  the  state  of  fine  powder  with  hydrochloric 
acid,  evaporating  to  dryness,  exhausting  the  residue  with  alcohol,  and 
precipitating  the  arsenic  from  the  filtrate  by  means  of  zinc.  A  simi- 
lar process  is  adopted  by  Westrumb,  who  however  uses  a  mixture  of 
hydrochloric  and  nitric  acid.  Geiger  &  Reimann  {Mag.  Pharm.  19, 139) 
digest  the  finely  divided  sulphur,  with  agitation,  in  ammonia,  and  filter. 
If  the  filtrate  contains  much  sulphide  of  arsenic,  that  substance  is  im- 
mediately precipitated  from  the  filtrate  on  the  addition  of  hydrochloric 
acid;  but  if  the  quantity  of  sulphide  of  arsenic  is  small,  precipitation 
does  not  take  place  unless  the  liquid  be  previously  mixed  with  a  small 
quantity  of  potassa  and  evaporated  to  a  few  drops.  From  pure  sulphur 
ammonia  extracts  nothing. 

Selenium  is  detected  in  sulphur  by  dissolving  the  whole  in  boiling 
caustic  potassa,  or  by  fusing  it  with  carbonate  of  potassa  and  dissolving 
the  fused  mass  in  water.  The  filtrate,  after  several  days*  exposure  to  the 
air^  deposits  selenium. 

Properties .  Solid  sulphur  is  dimorphous  (I.,  98),  aud  amorphous 
(I.,  104). 

a.  Native  sulphur  and  that  which  crystallizes  from  solution  in  bisul- 
phide of  carbon*  takes  the  form  of  acute  rhombic  ootohedrons.  {Fig. 
41—44,  and  others.)     a  :  a'=  84"  58';  a' :  a»  =  143<>  17';  « :  w'=78°  1'; 

*  Sulphur  crystallized  from  bisulphide  of  carbon  sometimes,  though  rarely,  exhibits 
the  oblique  prismatic  as  well  as  the  octohedral  form  of  crystallization.  The  prismatic 
crystals  take  the  primary  form  without  any  modification.  They  are  at  first  transparent, 
and  of  the  same  yellow  colour  as  the  octohedral  crystals,  bat  soon  become  opaque, 
crumbly,  and  nearly  white.   (Past«ur,  Compt.  Rend.  26,  48.)     [W.] 


SULPHUR.  157 

a':  jt>  =  108°  21^'.  Cleavage  parallel  to  the  o-faces.  (Mitscherlich,  Ann, 
Cltim.  Phys.  24,  265.)  Specific  gravity,  20454  :  of  native  sulphur,  2-033, 
Brmon;  2-050,  Kanten;  2.062—2-070,  Marchand  fy  Scheerer;  2*072, 
Molu;  of  sulphur  crystallized  from  solution  in  bisulphide  of  carbon,  1*9727, 
Bischof;  2  050,  Mat-chand  Sf  Scheerer;  of  rolled  sulphur,  1-868,  Bock- 
mann;  1'990,  Brisson;  1-977 — 2-000,  Thomson;  of  flowers  of  sulphur, 
at  4°  in  vacuo,  2-086,  Le  Royei*  Sf  bumas.  Very  brittle  and  friable; 
decrepitates  from  formation  of  cracks  when  warmed  in  the  hand.  Colour, 
pale  greenish-yellow,  becoming  orange-yellow  when  heated.  Transparent 
or  translucent.  Its  refracting  power  is  to  that  of  water  as  0-204 :  0'1336. 
(Wollaston.)  Does  not  conduct  electricity;  becomes  electrical  when 
rubbed  with  other  bodies.  Exhales  a  faint  odour  when  rubbed,  and  has 
a  scarcely  perceptible  taste. 

h.  When  melted  sulphur  is  allowed  to  cool  slowly  till  it  is  half 
solidified,  a  hole  then  made  in  the  crust,  and  the  yet  liquid  portion  poured 
out,  the  sulphur  is  obtained  in  very  long  and  thin  oblique  rhombic  prisms, 
belonging  to  the  oblique  prismatic  system.  Primary  form  {Fig.  81), 
with  the  faces  «,  a  and  m; — w' :  %  =  90''  32';  m  :  t  =  95°  46'  (Mitscherlich, 
comp,  Kupffer,  Po^^.  2,  41,  Bemhardi,  N,  Tr,  9,  2,  3.)  Sp.  gr.  =  1-982. 
(Marchand  &  Scheerer.)  According  to  the  assertion  of  Breithaupt  {J,  pr, 
Chem.  4,  257),  cited  on  page  98,  vol.  L,  the  crystals  h  appear  to  be  not 
only  rather  harder  than  the  crystals  a,  but  likewise  to  have  a  somewhat 
greater  density.  These  crystals  are  pale  brownish-yellow  and  perfectly 
transparent.  In  the  course  of  a  few  days,  at  ordinary  temperatures,  they 
become  opaque,  pale  yellow,  and  specifically  heavier,  assuming  internally 
the  structure  of  the  crystals  a,  while  externally  they  remain  as  pseudo- 
crystals  of  the  form  h.  The  slightest  agitation,  even  blowing  on  the 
crystals,  accelerates  this  change. 

By  cooling  them  as  slowly  as  possible,  and  leaving  them  at  perfect 
rest  for  24  hours,  they  may  be  rendered  more  permanent.  The  change 
from  6  to  a  begins  with  the  formation  of  isolated,  bright  yellow,  opaque 
spots,  which  gradually  spread  themselves  out.  When  the  crystals  have 
become  perfectly  opaque,  their  specific  gravity  is  found  to  be  increased 
from  1-982  to  2  038.  The  change  is  always  accompanied  by  the  for- 
mation of  internal  fissures.  If,  on  the  other  hand,  sulphur  be  kept  for 
twelve  hours  at  a  temperature  between  110°  and  100°,  its  specific  gravity 
diminishes  from  2*049  to  1*985  ;  but  if  it  remain  for  several  days  at  the 
ordinary  temperature  of  the  air,  its  density  again  rises  to  2-048.  If  a 
thermometer  be  immersed  in  sulphur  which  is  solidifying,  and  the  cooling 
of  the  solid  sulphur  be  retarded  by  surrounding  it  with  cotton,  slight 
blows  on  the  side  of  the  vessel  will  cause  a  rise  of  the  thermometer  of 
\°  to  1°,  and  repeated  blows  a  rise  of  2°  or  3°,  inasmuch  as  the  passage 
of  the  sulphur  from  &  to  a  is  attended  with  evolution  of  heat.  But  when 
once  the  sulphur  has  become  perfectly  opaque,  no  further  rise  of  tem- 
perature is  produced  by  agitation.  (Marchand  ht,  Scheerer.)  HoUed  sul- 
phur when  newly  cast  is  of  the  form  6,  but  after  a  time  changes  to  a. 
Flowers  of  sulphur  when  examined  by  the  microscope  present  the  ap- 
pearance, not  of  crystals,  but  of  smooth,  opaque  spherules  of  non-crystalline 
fracture.     (Fritzsche.) 

c.  Softy  aTnorpkoris  Sulphur.  When  sulphur  is  heated  till  it  acquires 
a  viscid  consistence,  and  then  poured  into  water  kept  as  cold  as  possible, 
it  becomes  soft  and  of  a  reddish-brown  colour,  and  acquires  a  density  of 
1*961:  when  it  has  become  quite  solid  but  is  still  coloured  brown,  the 
density  is  increased  to  1  -980 ;  and  when  it  has  become  quite  yellow,  to 


158  SULPHUR. 

2*041.  (Marehand  <fc  Seheerer.)  According  to  Osann,  the  specific grarity 
of  e  is  2*027.  (  Vid,  I.,  104.)  Soft  sulphur  hardens  in  the  course  of  20  or 
30  hours  (Dumas),  by  transformation  into  a.  The  brown  colour  which 
characterizes  the  amorphous  state  may  be  heightened  by  the  asphaltum 
which  is  often  mixed  with  sulphur  and  is  altered  by  the  action  of  heat. 
The  restoration  of  the  yellow  colour  after  a  time  is  no  objection  to  this 
yiew  ;  for  the  opacity  which  the  sulphur  acquires  at  the  same  time  prevents 
the  brown  colour  from  being  perceived.  Fourcroy  and  Thomson  were 
of  opinion  that  sulphur  in  the  soft  state  is  partially  oxidized ;  but  Irvine 
and  Sir  Humphry  Davy  have  shown  that  the  soft  condition  is  produced 
equally  well  out  of  contact  of  air. 

Sulphur  melts  at  104*5  (Berzelius),  at  107°  (Dumas),  at  108"— 109* 
(Dalton),  at  111*75*^—112°  (Marehand  &  Seheerer),  at  112-2"  (Fran- 
kenheim.  J.  pr.  Chem.  16,  7),  and  forms  a  brownish-yellow,  transparent, 
thin,  oily  liquid,  which,  according  to  Osann  {Pogg.  31,  33),  has  a  specific 
gravity  of  1927.  According  to  Knox,  this  liquid  conducts  the  electric 
current  of  a  sixty-pair  battery.  (See,  on  the  contrary,  p.  313.,  Vol.  I.) 
Considerable  masses  of  liquid  sulphur  solidify  a  few  degrees  below  the 
melting  point;  smaller  masses  often  remain  liquid  at  ordinary  tem- 
peratures. Sulphur  begins  to  solidify  between  109"  and  108".  (Dumas.) 
During  the  process  of  solidification,  the  temperature  falls  to  99°  or  100", 
and  rises  again  to  between  109*4°  and  110".  (Marx,  Schw.  60, 1.)  Con- 
siderable masses  of  melted  sulphur  may  cool  down  to  108",  or  even  to 
105°  before  solidifying;  but  as  soon  as  solidification  begins,  the  temper- 
ature rises  to  112°,  and  remains  there  till  the  whole  is  solidified.  (Fran- 
kenheim.)  Solidification  takes  place  at  111*5°:  when  it  is  completed, 
and  the  temperature  of  the  sulphur  has  fallen  somewhat  below  that  point, 
it  often  rises  suddenly  again  to  111*5".  (Marehand  k  Seheerer.)  Sulphur 
in  small  drops  often  remains  liquid  at  ordinary  temperatures,  and  soli- 
difies when  touched  with  solid  bodies.  (I.,  9;  compare  also  Belleni, 
N.  Qtiart.  J.  of  Sc.  2,  469;  Frankenheim,  J.  pr.  Chem.  16,  7.)  The 
minute  drops  deposited  by  the  condensation  of  sulphur-vapour  on  a  glass 
plate  remain  liquid  for  several  days  when  left  at  rest,  and  finally  soli- 
dify in  the  form  of  smooth  globules :  in  this  manner  also  flowers  of 
sulphur  are  produced :  but  on  agitation  or  exposure  to  light,  the  drops 
solidify  in  a  few  hours,  spreading  themselves  out  on  the  glass  plate  in 
the  form  of  opaque  hemispheres  covered  with  crystalline  points  of  the 
rhombic  octohedral  form.  If  the  glass  plate  be  wetted  with  oil,  the 
crystals  are  larger  and  more  quickly  formed.  (Fritzsche,  Pogg.  42, 453.) 
At  a  higher  temperature,  the  melted  sulphur  loses  its  oily  state  and 
acquires  a  thick  viscid  consistence  like  turpentine :  it  likewise  assumes 
a  dark  red-brown  colour,  and  is  no  longer  transparent,  excepting  in  thin 
films.  In  this  viscid  state,  the  density  of  sulphur  is,  according  to  Osann, 
only  1*751.  At  160",  sulphur  begins  to  turn  red  and  viscid;  between 
220°  and  250",  it  is  so  thick  that  it  will  not  run  out  when  the  containing 
vessel  is  inverted;  it  also  exhibits  a  red-brown  colour.  (Dumas.)  Thick- 
ening begins  at  a  temperature  near  260°.  When  melted  sulphur  is 
heated,  its  temperature  remains  stationary  for  some  time  between  250" 
and  260°,  but  afterwards  rises  with  proportionally  greater  quickness: 
on  the  other  hand,  sulphur  heated  above  260°  cools  down  with  tolerable 
regularity  at  first;  but  after  the  temperature  has  fallen  to  260°,  it  sud- 
denly becomes  stationary  for  several  minutes  and  oscillates  within  a  few 
degrees  above  and  below ;  after  that,  it  falls  regularly.  Hence  it  appears 
that  sulphur,  in  passing  from  the  oily  to  the  viscid  state,  renders  heat 


SULPHUR.  159 

latent.  (Frankenheim.)  Results  not  in  accordance  with  these  have  been 
obtained  by  Marx.  {Schw.  60,  1.)  When  viscid  sulphur  is  dropped  into 
oil,  it  becomes  covered  with  well  developed  crystals  and  loses  its  trans- 
parency. (Fritzsche.) 

At  still  higher  temperatures,  up  to  the  boiling  point,  sulphur  again 
becomes  more  fluid,  but  not  so  much  so  as  at  120®;  it  likewise  acquires 
greater  transparency,  but  retains  a  brown-red  colour.  The  more  fluid 
state  commences  at  207'5°,  according  to  Osann,  and  at  250°,  according  to 
Dumas.  When  sulphur,  by  continued  heating  at  a  temperature  of  300® 
has  been  wholly  brought  into  the  brown-red  condition,  and  is  then 
rapidly  cooled,  it  exhibits  a  uniform  decrease  of  temperature  and  does 
not  pass  through  the  intermediate  viscid  state  ;  but  if  it  be  slowly  cooled,  it 
becomes  viscid,  the  passage  into  this  state  being  accompanied  by  a  simulta- 
neous interruption  in  the  fall  of  temperature.  (Frankenbeim.)  Sulphur 
fused  at  various  temperatures  and  then  quickly  cooled  in  single  drops 
by  immersion  in  cold  water  behaves  as  follows:  at  110° — ITO"",  it  soli- 
difles  to  a  yellow  mass  of  the  ordinary  colour  of  sulphur.  At  190°,  it  is 
at  first  soft  and  transparent,  but  soon  becomes  brittle  and  opaque,  ex- 
hibiting  the  ordinary  colour.  At  220°,  it  becomes  soft,  transparent,  and 
brownish-yellow.  At  230° — 260°,  it  becomes  perfectljr  soft,  ductile,  trans- 
parent, and  of  a  reddish  colour.  At  the  boiling  pomt,  very  soft,  trans- 
parent, and  red-brown.  Fusion  for  a  long  time  has  nothing  to  do  with 
these  conditions;  all  depends  on  the  temperature.  If  the  sulphur  be 
poured  into  the  water  in  large  masses,  the  inner  portions,  which  cool 
slowly,  solidify  in  the  form  of  ordinary  sulphur.  Rapid  cooling  prevents 
the  crystallization.  (Amorphism.)  Dumas.  The  soft,  plastic  sulphur  ob- 
tained by  rapid  cooling  in  water  serves  to  take  impressions  of  medals. 

Sulphur  boils  at  293°,  according  to  Davy,  and  at  440°,  according  to 
Dumas  (Ann.  Ohim.  Phys,  50,  175), — and  is  converted  into  an  orange- 
coloured  vapour,  which  has  a  faint  and  characteristic  odour,  and  deposits 
small  drops  of  sulphur  on  cold  bodies. 

Milk  of  Sulphur,  Lac  sulphuris.  Sulphur  separated  in  the  cold,  from 
aqueous  solutions  containing  hydrosulphuric  acid.  To  obtain  it,  prepare 
one  of  the  following  solutions :  a.  An  aqueous  solution  of  liver  of  sulphur. 
h.  The  solution  a  thoroughly  saturated  by  boiling  with  sulphur.  (Bucholz.) 
c.  Sulphide  of  potassium,  obtained  by  igniting  sulphate  of  potassa  with 
charcoal,  then  dissolved  in  water,  and  the  solution  saturated  with  sulphur 
at  a  boiling  heat.  (Bucholz.)  d.  Solution  of  caustic  potash  boiled  with 
sulphur  till  saturated,  e.  One  part  of  quicklime  slaked  with  3  parts 
water,  and  then  boiled  with  2  parts  sulphur  and  13  parts  water.  One 
of  these  liquids,  after  being  left  to  stand  for  some  days,  then  filtered  and 
properly  diluted  with  water,  is  precipitated  by  sulphuric,  hydrochloric, 
or  acetic  acid  free  from  metal.  With  c,  only  hydrochloric  or  acetic  acid 
can  be  used.  The  acid  must  be  added  in  small  portions  at  a  time,  with 
constant  stirring,  to  the  sulphur  solution,  and  in  such  quantity  as  not  to 
decompose  it  completely;  and  the  precipitate  immediately  collected  on  a 
filter  and  thoroughly  washed.  For  the  sulphur  solutions,  especially  d 
and  e,  likewise  contain  alkaline  hyposulphites,  from  which,  if  the  acia  be 
added  in  excess,  or  the  mixture  left  to  stand  a  long  time,  yellow  sulphur 
is  precipitated  and  becomes  mixed  with  the  milk  of  sulphur.  {Vid. 
Wackenroder,  Br.  Arch.  26,  180.) 

Milk  of  sulphur  is  a  white  powder  with  a  tinge,  not  of  yellow,  but  of 
grey — feels  gritty  between  the  fingers — ^and  has  a  scarcely  perceptible 
taste  and  odour. 


160  SULPHUR. 

That  milk  of  sulphur  is  not,  as  asserted  by  Thomson,  a  hydrate  of 
sulphur,  has  been  shown  by  Bucholz  {Tascherib.  1808,  1«)5,)  and  Bischof 
{Sckw,  43,  392).  When  thoroughly  dried  and  then  heated,  it  gives  off^ 
not  water,  but  a  small  quantity  of  hydrosulphuric  acid  gas,  and  fuses 
together  in  the  form  of  ordinary  sulphur.  (Berzelius,  Le/irb.  1,  213.) 
Since  this  evolution  of  hydrosulphuric  acid  is  constant,  and  cannot  be 
prevented  by  previously  washing  the  powder  with  water, — and  since 
milk  of  sulphur  is  precipitated  only  from  liquids  which  contain  hydro- 
sulphuric acid,  Rose  (Pogg-  47,  166)  regards  it  as  sulphur  having 
hydrosulphuric  acid,  or  rather  persulphide  of  hydrogen,  adhering  to  it. 
According  to  Osaun  {Kastn.  Arch.  4,  344),  it  also  contains  4  per  cent, 
of  carbon ;  but  this  is  probably  nothing  but  an  accidental  impurity. 


Compounds  of  Sulphur. 

Sulphur  and  Oxygen. 

A.     Hyposulphurous  Acid.    SO  or  S*0*. 

Oxide  of  Sulphur^  Sulphuretted  Sulphurous  acid,  Dithionous  acid,  Un- 
terschweflige  Sdure,  Acide  hyposulfureux,  Acidum  hypostdfurosum. 

Formed,  in  combination  with  salifiable  bases:  1.  When  certain 
metals,  zinc  for  example,  are  dissolved  in  aqueous  sulphurous  acid.  2 
atoms  of  zinc  with  3  atoms  of  sulphurous  acid  form  1  atom  of  sulphite 
and  1  atom  of  hyposulphite  of  zinc  : 

2Zii  +  3S0«  =  ZnO,  S0«  +  ZnO,  S^O". 

(Mitscherlich,  Fogg.  8,  442.) — 2.  When  an  aqueous  solution  of  an 
alkaline  sulphite  is  boiled  with  sulphur,  the  sulphur  being  dissolved  in 
considerable  q  u  an  ti  ty : 

(KO,SO«  +  S=KO,S*O0 

3.  When  the  solution  of  an  alkaline  sulphite  is  decomposed  by  a  small 
quantity  of  hydrosulphuric  acid,  or  of  the  sulphide  of  an  alkali-metal. 
With  hydrosulphuric  acid  the  decomposition  is  probably — 

2K0,  2S0«  +  HS  =  2K0,  3S0  +  HO. 

and  with  sulphide  of  potassium — 

2K0,  2S0*  +  KS  =  3K0,  3S0. 

4.  When  the  solution  of  the  sulphide  of  an  alkali-metal  is  mixed  with 
sulphurous  acid.  (Vauquelin.)  In  this  case,  sulphur  and  hydrosulphuric 
acid  are  set  free,  and  a  small  quantity  of  an  alkaline  sulphite  is  formed 
together  with  the  hyposulphite.  (Mitscherlich,  Po^^.  8,  441.) — 5.  When 
the  solution  of  a  poly-sulphide  of  an  alkali-metal  is  exposed  to  the  air — 

KS«  +  30  =  KO,  S«0». 

6.  When  sulphur  is  fused  at  a  gentle  heal  with  an  alkaline  hydrate,  or 
boiled  with  an  aqueous  solution  of  the  alkali.  In  this  case,  a  pentasul- 
phide  of  the  metal  is  formed  at  the  same  time. 

3KO  +  128  =  KO,  S*  O*  +  2KS.\ 


HYPOSULPHUROUS  ACID.  161 

7.  When  aqnoous  eolations  of  various  alkaline  salts,  saturated  with 
h^drosulphuric  acid,  are  heated  to  the  boiling  point  in  contact  with  the 
air.  Borax,  chlorate,  neutral  tartrate,  and  acetate  of  potassa,  phosphate 
and  acetate  of  soda,  and  acetate  of  baryta,  treated  in  this  manner,  yield 
small  quantities  of  alkaline  hyposulphites;  sulphate  and  nitrate  of 
potassa,  and  sulphate  of  soda  yield  but  a  trace.  (L.  A.  Buchncr,  Bepert, 
61,  36.) 

Calculation.  Or:  Or: 

S     ....  16  ....  66-67  2S  ....  32  ....  66-67  ....      S    ....  16  ....  33-33 

O     ....     8  ....  33-33  20....  16  ....  3333  ....  SO«   ....  32  ....  6667 

SO    ....  24  ....100-00  S*0«....  48  ....10000       S<b«    ....  48  ....10000 

(S«0«  =  2  .  201-17  +  2  .  100  =  602-34.     Berzelius.) 

This  acid  is  not  known  in  the  free  state,  on  account  of  its  tendency, 
when  separated  from  its  combinations,  to  resolve  itself  into  sulphurous 
acid  and  sulphur.  (S^0'  =  SO'+S.)  When  an  alkaline  hyposulphite, 
dissolved  in  water,  is  decomposed  by  the  action  of  a  stronger  acid,  the 
liquid,  according  to  Herschel,  acquires  a  harsh,  sour,  and  very  bitter  taste, 
and  the  property  of  precipitating  metallic  sulphides  from  solutions  of  nitrate 
of  mercurous  oxide  and  nitrate  of  silver :  it  exerts  no  immediate  action  upon 
salts  of  zinc,  iron,  and  copper;  but  in  a  few  seconds,  especially  if  heat  be 
applied,  half  of  the  sulphur  is  precipitated,  and  the  other  half  remains  in 
the  liquid,  combined  with  the  whole  of  the  oxygen  in  the  form  of  sul- 
phurous acid.  According  to  H.  Rose,  a  very  small  quantity  of  the  acid 
remains  undecomposed  for  several  weeks.  The  cause  of  the  decompo- 
sition may  be,  that  water  has  a  much  greater  affinity  for  sulphurous  than 
for  hyposulphurous  acid.  It  must,  however,  be  observed,  that  when 
anhydrous  hyposulphite  of  strontia  is  decomposed  by  hydrochloric  acid 
gas,  or  by  alcohol  saturated  with  that  gas  (in  which  case,  only  a  small 
quantity  of  water  can  be  formed  from  the  oxygen  of  the  strontia  and  the 
hydrogen  of  the  hydrochloric  acid),  the  acid  which  is  set  free  is 
resolved  into  sulphurous  acid  and  sulphur.  (Gay-Lussac.)  Also,  when 
hyposulphite  of  lead  diffused  through  water  at  0°  is  decomposed  by 
hydrosulphuric  or  sulphuric  acid,  an  aqueous  solution  of  hyposulphurous 
acid  is  at  first  obtained,  but  that  acid  is  quickly  resolved  into  sulphurous 
acid  and  sulphur.  (Pelouze.)  Sulphur  precipitated  from  aqueous  solu- 
tions of  alkaline  hyposulphites  on  the  addition  of  an  acid,  takes  the 
form,  not  of  milk  of  sulphur,  but  of  plastic  sulphur,  forming  globules  of 
different  magnitudes,  which  remain  soft  for  a  long  time  under  water,  but 
become  crystalline  when  exposed  to  the  air  or  placed  in  contact  with 
fixed  oils. 

Hyposulphurous  acid  in  combination  with  salifiable  bases  forms  salts 
called  Hyposulphites,  DUkioniies,  SulpkureiUd  Sulphites,  Salts  of  Sulphu- 
ric Oxide,  UnterschwefUgsauren  Salze.  For  their  formation  and  prepa- 
ration, vid,  p.  160.  They  generally  contain  one  atom  of  acid,  S*0*, 
combined  with  one  atom  of  base.  They  appear  to  be  unable  to  exist 
without  at  least  one  atom  of  water.  (H.  Rose,  Pogg,  21,  439.)  The 
alkaline  hyposulphites,  when  heated  out  of  contact  of  air,  are  resolved 
into  water,  sulphur,  and  hydrosulphuric  acid,  which  escape,  and  a 
mixture  of  a  metallic  sulphide  with  an  alkaline  sulphate,  the  pro- 
portions of  which  vary  according  to  the  temperature.  (H.  Rose.)  When 
thrown  into  nitre  in  a  state  of  fusion,  they  evolve  red  vapours.  ^H. 
Rose.)  Boiled  with  water  and  sulphur,  they  decompose  the  water,  evolve 
hydrosulphuric  acid,  and  form  a  sulphate  of  the  base.  (Pelouze,  Ann. 
VOL.  n.  M 


162  SULPHUR. 

Chim.  Fhy$.  79^  S6*)  The  aqueous  solution  of  an  alkaline  hyposulphite 
remains  unaltered  in  the  air^  according  to  Gray-Lussac ;  but  if  the  salt 
contains  more  than  one  atom  of  alkali  for  each  atom  of  S'O^  it  is  con- 
verted first  into  a  sulphite,  and  then  into  a  sulphate* 

KO,  S«0«  +  KO  +  40  =  2KO,  2S0». 
When  digested  in  nitric  acid  till  the  sulphur  which  is  precipitated  at 
first  is  re-oxidized  and  dissolyed,  they  yield  two  atoms  of  sulpnuric  acid 
for  each  atom  of  alkali.  (Gay-Lussac.) 

KO,  S«0«  +  40  =  KO  +  2S0». 

Stronger  acids,  even  sulphurous  acid,  decompose  the  hyposulphites,  the 
acid  of  which  is  then  resolved  into  sulphurous  acid  and  sulphur.  Hydro- 
chloric acid  separates  sulphurous  acid,  with  eflervescence,  from  the 
fixed  hyposulphites.  All  alkaline  hyposulphites  are  soluble  in  water, 
the  baryta-salt,  however,  but  slightly.  The  solutions  give  the  following 
reactions:  With  protochloride  of  tin  dissolved  in  aqueous  hydrochhric 
add:  An  immediate  brown  precipitate,  even  when  the  quantity  of 
alkaline  hyposulphite  is  very  small.  (H.  Rose.)  Lead-salts:  White 
precipitate;  turning  black  even  below  100®.  (Herschel.)  Solution  of 
protochloride  of  copper,  in  the  cold :  White  precipitate  of  dichloride  of 
copper.  Oxygen-salts  of  protoxide  of  copper,  in  the  cold :  Nothing,  at 
first;  turbidity  after  some  time.  All  proto-salts  of  copper,  at  a  boiling 
heat :  Black  precipitate  of  sulphide  of  copper,  free  sulphuric  acid  remain- 
ing in  the  liquid. 

CuO,  S*0«  =  CuS,  SO*.    (H.  Roac.) 

(According  to  Pfaff,  Schw.  44,  490),  proto-salts  of  copper  give  a  yellow- 
green  precipitate,  which  after  a  time  becomes  red-brown.)  Nitrate  ofmer- 
curous  oxide :  Immediate  black  precipitate.  (H.  Rose.)  Protochloride  of 
mercury  and  oxygen-salts  of  mercuric  oxide  not  in  excess:  White  preci- 
pitate of  mercuric  hyposulphite,  which  turns  first  yellow,  then  brown, 
and  is  ultimately  converted  into  black  sulphide  of  mercury — the  change 
taking  place  very  rapidly  at  a  boiling  heat — ^while  free  sulphuric  acid 
remains  in  the  liquid.  The  same  mercuric  salts  used  in  excess :  White 
precipitate,  which  settles  down  slowly,  remains  white  even  on  boiling, 
and  consists  of  a  compound  of  sulphide  of  mercury  with  the  protochloride, 
or  with  an  oxygen-salt  of  mercuric  oxide ;  the  supernatant  liquid  contains 
free  sulphuric  acid.  (H.  Rose.)  According  to  Wackenroder  and  L.  A. 
Buchner  {Repert.  61,  24),  on  the  contrary,  nitrate  of  mercuric  oxide  gives 
a  copious,  lemon-yellow  floculent  precipitate,  which  when  the  mercuric 
salt  is  in  excess,  becomes  yellowish -white.  Nitrate  of  silver:  White 
precipitate,  which  becomes  first  yellow,  then  brown,  and  is  finally  con- 
verted  into  black  sulphide  of  silver — ^the  change  being  greatly  accelerated 
by  heat — ^while  free  sulphuric  acid  remains  in  the  liquid.  (Herschel ;  H. 
Rose.)  The  alkaline  hyposulphites  dissolve  freshly  precipitated  chloride 
of  silver. 


IT    B.      pBNTATfilONiC  AclD.      S*  0*. 

Tersulphuretted  Hyposulphuric  add,  TermUhyposvlphurtc  add. 

^  Formation.  1 .  By  the  mutual  action  of  sulphurous  and  hydrosulphuric 
acid : — 5  atoms  of  sulphurous  acid  and  5  atoms  of  hydrosulphuric  acid, 
react  upon  one  another  in  such  a  manner  as  to  form  1  atom  of  pen- 


PENTATHIONIC  ACID.  16S 

tathionic  acid^  5  atoms  of  water,  and  5  atoms  of  sulphur;  which  separate 
in  the  solid  state.  (Wackenroder.) 

5S0«  +  5HS  =  S»  O*  +  5H0  +  5S. 

2.  Bj  the  action  of  aqueous  solution  of  sulphurous  acid  on  chloride  of 
sulphur. 

This  acid  is  not  known  to  exist  in  the  separate  state. 

Calcnlatton.  Lemnr.  Or:  CalcnUtioii. 

58    80  66-67  6667  S«0»  72  60 

50    40  33-33  33-33 S»  48  40 

S*0»   120  10000  100-00  S»0»     120  100 

(S*0*  «  5  .  201-17  +  5  .  100  s  1505-85.    BerzeUua.) 

ComhifuUiotis,  a.  With  Water.  Hydraied  Pentathionic  add, 
(1.)  Wackenroder  passes  sulphuretted  hydrogen  in  excess  through  a  satu- 
rated solution  of  sulphurous  acid  in  water — filters  and  digests  the  milky 
filtrate  with  slips  of  clean  metallic  copper,  till  it  becomes  clear — filters 
again — removes  the  dissolved  copper  by  sulphuretted  hydrogen — and 
drives  ofiTthe  excess  of  the  latter  by  the  application  of  a  gentle  heat.  The 
solution  thus  obtained  is  colourless  and  destitute  of  odour  j  it  may  be  con- 
centrated without  decomposition  till  it  attains  the  specific  gravity  of  1  '37.— 
f2.)  Kessler  passes  sulphurous  and  hydrosulphuric  acid  gases  alternately 
through  water,  till  the  precipitated  sulphur  forms  a  thick  magma  at  the 
bottom  of  the  vessel — digests  the  filtered  liquid  with  freshlv  precipitated 
carbonate  of  baryta,  to  remove  sulpduric  acid — filters,  and  concentrates 
the  filtrate  over  a  water-bath,  till  it  attains  a  density  of  1*25 — 1*3.  The 
acid  liquid  thus  obtained  may  be  further  concentrated  in  vacuo,  to  the 
density  of  1-6  at  the  temperature  of  22°  (71*6°  F.). 

Hydrated  pentathionic  acid  is  colourless  and  inodorous,  and  hsjs  a 
strongly  acid  taste,  inclining  to  bitter.  It  may  be  preserved  nnchanged 
at  the  temperature  of  the  air;  but  on  attempting  to  concentrate  it  by 
heating  beyond  the  density  of  1*37,  it  is  decomposed,  sulphuretted  hydro- 
gen, and  afterwards  sulphurous  acid  being  evolved,  while  sulphuric  acid 
and  sulphur  remain  behind.  It  is  not  decomposed  by  sulphuretted 
hydrogen,  or  by  dilute  hydrochloric  or  sulphuric  acid ;  the  latter,  how- 
ever, when  concentrated  decomposes  it.  By  nitric  acid,  hypochlorous 
acid,  or  chlorine,  it  is  oxidated  and  converted  into  sulphuric  acid. 
Metallic  copper  and  iron  decompose  it  at  a  boiling  heat,  the  foi-mer  with 
evolution  of  sulphurous  acid  and  formation  of  sulphide  of  copper;  the 
latter  with  evolution,  first  of  sulphuretted  hydrogen,  then  of  sulphurous 
acid|  a  portion  of  the  latter  also  remaining  in  the  liquid.  (Wackenroder.) 
A  moderately  concentrated  solution  of  pentathionic  acid  gives  off  a  faint 
sulphurous  smell  when  boiled,  but  does  not  evolve  sulphurous  acid  ^ 
except  when  highly  concentrated;  on  boiling  it  with  hydrochloric  acid, 
the  odour  of  sulphuretted  hydrogen  is  perceptible.  On  boiling  the  acid 
with  solution  of  caustic  potash,  hyposulphite  and  sulphate  of  potassa^ 
and  sulphide  of  potassium  are  formed.  (S»0»  =  SO»+6»0*H-28.) 
(Kessler.) 

Sulphate  of  copper  added  to  a  solution  of  pentathionic  acid  produces  a 
brown  precipitate  after  long  boiling.  Niirate  of  mercuroui  oxide  gives  a 
yellow  precipitate  which  slowly  blackens  on  boiling; — Chloride  of  mercury: 
by  degrees,  a  yellowish  precipitate,  consisting  of  a  compound  of  sulphide 
and  chloride  of  mercury  mixed  with  free  sulphur; — Cyanide  of  mercury : 
by  degrees,  a  yellow  precipitate  which  blackens  slowly  in  the  cold,  imme* 

u  2 


164  SULPHUR* 

diately  on  boiling; — NUrate  of  silver  :  a  yellow'precipitate^  which  soon 
tarns  olack.  When  a  solntion  of  pentathionic  acid  is  rapidly  mixed  with 
excess  of  ammonia,  the  addition  of  an  ammoniacal  solntion  of  nitrate  of 
silver  quickly  produces  a  brown  colour,  which  gradually  becomes  darker, 
while  sulphide  of  silver  separates  from  the  liquid.  An  ammoniacal  solution 
of  chloride  of  mercury  added  to  the  same  liquid  gradually  produces  a  black 
precipitate  of  sulphide  of  mercury;  and  on  the  addition  of  hydrosulphuric 
acid,  a  separation  of  sulphur  takes  place.  (Kessler.) 

b.  With  Salifiable  Bases.  The  salts  of  this  acid,  the  PefUathiotuUes, 
have  not  been  much  examined.  They  are  very  instable, — so  much  so, 
that  it  is  difficult  to  obtain  them  in  the  solid  state.  In  hci,  the  fifth  atom 
of  sulphur  in  the  acid  appears  to  be  retained  by  only  a  feeble  affinity;  and 
in  presence  of  a  strong  base,  especially  if  the  solution  be  concentrated, 
this  last  atom  of  sulphur  is  separated,  and  the  result  is  the  formation  of 
tetrathionic  acid,  the  salts  of  which  have  greater  stability.  Sometimes 
two  atoms  of  sulphur  are  given  up  and  trithionic  acid  (S^O^)  is  produced. 
Kessler  found  that  on  mixing  solution  of  pentathionic  acid  of  specific 
gravity  1*32  (prepared  by  either  of  the  methods  aboye  described)  with 
solution  of  acetate  of  potassa  in  alcohol  of  96  per  cent.,  washing 
the  precipitate  with  alcohol,  and  dissolying  it  in  warm  water,  a  con- 
siderable quantity  of  sulphur  remained  undissolved,  and  the  solution 
mixed  with  alcohol  yielded  crystals  having  the  form  and  composition 
of  tetrathionate  of  potassa,  KO,  S*0^.  The  pentathionates  of  baryta 
and  lead  are  soluble  in  water,  but  cannot  be  obtained  in  the  solid 
state  by  evaporation  even  in  vaxTuo,  decomposition  taking  place  as 
soon  as  the  solutions  attain  a  certain  degree  of  concentration.  Lenoir, 
however,  obtained  the  baryta  salt  in  definite  crystals  by  mixing  the 
freshly  prepared  aqueous  solution  with  strong  alcohol.  The  salt  then 
separated  abundantly  in  transparent  silky  prisms  which  changed  within 
the  liquid  to  larger  and  well-defined  crystals.  These  crystals  were 
analysed,  and  found  to  consist  of  BaO,  S^O^  HO.  This  determines  the 
composition  of  the  acid,  and  shows  it  to  be  isomeric  (or  rather,  polymeric) 
with  hyposulphurous  acid. 


IF  C.    Tetrathionic  Acid.    S*0*. 

BimlphuretUd  Syposulphuric  acid,  Bisul-hyposulphuric  acid. 

Formation,  1.  By  the  action  of  iodine  on  solutions  of  the  hyposul- 
phites, that  of  soda,  for  example,  2  At.  hyposulphite  of  soda  and  1  At. 
iodine  producing  1  At.  iodine  of  sodium  and  1  At.  tetrathionate  of 
soda. 

2  (NaO,  S0«)  +  I  =  Nal  +  NaO,  S*  O*. 

2.  By  the  decomposition  of  pentathionic  acid  (see  aboye).  Fordos  & 
061is,  in  examining  the  action  of  aqueous  solution  of  sulphurous  acid  on 
chloride  of  sulphur,  were  at  first  led  to  suppose  that  both  tetrathionic  and 
trithionic  acid  were  therebyproduced;  but  they  afterwards  found  that  these 
two  acids  were  not  formed  at  first — but,  at  a  later  period,  by  the  decom- 
position of  the  pentathionic  acid  produced  in  the  first  instance :  hence 
they  concluded  that  pentathionic  acid  is  the  only  acid  of  the  series  pro- 
duced by  the  direct  action  of  aqueous  sulphurous  acid  on  chloride  of 
sulphur. 


.    TETRATHIONIC  ACID.  165 

Tetrathionic  acid  has  not  been  obtained  in  the  separate  state :  its  com- 
position is  as  follows : — 

Calculation.  Or:  Calculation. 

4S   64  61-54  S«0*   72  69*23 

50  40  38-46 S«    32  3077 

S«0*    ....104  100-00  100    104  10000 

S^0»  =  4  .  201-17  +  5  .  100  =  1304-68.    BerzeUus.) 

Combinations,  a.  With  Water.  HydraUd  Tetratkionic  acid.  (1.) 
When  hyposulphite  of  baryta  is  dissolved  in  a  very  small  quantity  of 
water,  and  iodine  added  in  successive  portions  to  the  solution,  iodide  of 
barium  and  tetrathionate  of  baryta  are  formed,  and  both  dissolve  in  the 
water.  The  latter,  however,  is  soon  deposited  in  flakes  which  conti- 
nually increase  in  abundance,  inasmuch  as  the  quantity  of  water  present 
is  not  sufficient  to  dissolve  the  whole  of  the  salt.  Complete  saturation 
having  been  attained,  the  magma  of  crystals  is  digested  in  strong  alcohol, 
which  dissolves  the  iodide  of  barium  and  excess  of  iodine,  but  leaves  the 
tetrathionate  of  baryta  undissolved  in  the  form  of  a  white  powder;  and 
by  dissolving  this  powder  in  a  very  small  quantity  of  water  and  leaving 
the  solution  to  spontaneous  evaporation,  the  salt  is  obtained  in  beautifcd 
cnrstals:  the  addition  of  a  little  alcohol  facilitates  the  crystallization. 
The  salt  thus  obtained  being  dissolved  in  water,  sulphuric  acid  added  to 
the  solution  in  quantity  just  sufficient  to  pecipitate  the  baryta,  and  the 
liquid  filtered,  a  solution  of  tetrathionic  is  obtained  which  may  be  con- 
centrated to  a  considerable  extent  by  evaporation.  (Fordos  &  Gelis, 
Compt,  Rend.  15,  920.)  (2.)  Kessler  finds  that  the  acid  obtained  by  the 
preceding  process  is  never  absolutely  pure,  because  tetrathionic  acid,  by 
contact  with  strong  bases,  such  as  baryta,  is  resolved,  more  or  less,  into 
trithionic  acid  and  sulphur  (S'O*  =  S^O*  +  S).  To  avoid  this  source  of 
impurity,  Kessler  prepares  the  acid  from  the  lead  salt.  This  he  obtains 
by  pouring  a  warm  dilute  solution  of  2  parts  of  hyposulphite  of  soda, 
into  a  solution  of  3  parts  of  acetate  of  \esA,  likewise  warm  and  dilute 
— ^washing  the  precipitate,  and  mixing  it  while  yet  moist  with  1  part  of 
iodine:  in  a  few  aays,  the  whole  is  converted  into  iodide  of  lead  and  solution 
of  tetrathionate  of  lead  perfectly  free  from  trithionic  acid.  The  lead  being 
precipitated  from  this  solution  oy  sulphuric  acid,  and  the  excess  of  that 
acid  removed  by  digestion  with  carbonate  of  baryta,  a  pure  solution  of 
tetrathionic  acid  is  obtained,  which  may  be  evaporated  over  the  water- 
bath  to  a  small  bulk. 

The  solution  of  tetrathionic  acid  is  colourless  and  transparent;  has 
about  the  same  degree  of  stability  as  hyposulphuric  acid :  by  boiling,  it  is 
resolved  into  sulphur,  sulphurous  acid,  and  sulphuric  acid :  hydrochloric 
and  sulphuric  acid  do  not  decompose  it,  but  nitric  acid  causes  a  precipi- 
tation of  sulphur.  (Fordos  &  Gelis.)  According  to  Kessler,  on  the  con- 
trary, it  is  not  decomposed  by  boiling,  but  evolve  s sulphuretted  hydrogen 
when  mixed  with  hydrochloric  acid  and  gently  warmed.  (The  acid 
examined  by  Fordos  &  Gelis  probably  contained  trithionic  acid.)  When 
boiled  with  solution  of  caustic  potash,  it  is  converted  into  hyposulphite 
and  sulphate  of  potassa,  together  with  sulphide  of  potassium. 

S<0»  =  SO*  +  S«0«  +  S.  {Keuler.) 

Tetrathionic  acid  resembles  pentathionic  acid  in  its  behaviour  with 
solutions  of  sulphate  of  copper,  nitrate  of  mercurous  oxide,  chloride  of  mer- 
cury, cyanide  of  mercury,  and  nitrate  of  silver;  but  is  distinguished  from 


166  SULPHUR, 

pentathionio  aoid  by  ite  behaviour  with  an  ammoniacal  solution  of  lilyer. 
When  tetrathionic  acid  is  supersaturated  in  the  cold  with  ammonia^  no 
alteration  is  produced  in  it  by  the  addition  of  ammoniacal  solution  of 
nitrate  of  silver^  or  cyanide  of  mercury,  or  finally  by  sulphuretted  hydro- 
gen. (For  the  corresponding  reactions  of  pentathionio  acid,  vid»  pp.  163, 
164.) 

b.  With  Salifiable  Bases.  TetrathioncUes.  These  salts  are  much  more 
stable  than  the  pentathionates :  several  of  them  have  been  obtained  in  the 
solid  state,  and  will  be  described  hereafter.  The  acid  is  however  liable, 
especially  when  in  contact  with  a  strong  base,  to  resolve  itself  into  trithionic 
acid  and  sulphur ;  and  the  salts  are  particularly  prone  to  this  decomposition 
when  their  aqueous  solutions  are  concentrated  by  evaporation.  The  best 
mode  of  obtainiug  them  in  the  crystalline  state  is  to  mix  the  aqueous 
solutions  with  strong  alcohol.  In  this  manner  the  salts  of  potassa,  baryta, 
strontia  and  lead  have  been  obtained  in  well-defined  crystals.  IT 


D.    Trithionic  Acid.    S'O*. 

StdpkureUed  Syposulphuric  acid,  MoTioml-hyposulphurie  acid,  Acide  hy^ 
pottdfurique  tulfuri,  NiederBckwefeltaure. 

Formation.  1.  By  gently  heating  an  aqueous  solution  of  bisolphitd 
of  potassa  with  sulphur.  (  rid,  seq.) — 2.  By  the  decomposition  of  penta- 
thionio and  tetrathionic  acid.  (p.  164). 

Not  known  in  the  free  state. 

Acoording 

to  Langlois.  Or:    Calculation.  Or:  Calculation.  Or:        Calculation. 

3S   48  ....  54-55  SO   24  ....  27-27  S«0«  48  ....  54*55  S  ....  16  ....  181« 

50  40  ....  45-45  2S0«  64  ....  72-73  SO"  40  ....  4545  S"0«.  72  ....  8182 

S«0».  88  ....10000  S»0*....  88  ....100-00    S^O*  ....  88  ....100-00    S«0»  88  ....lOOOO 
(S^O*  «  3.201-17  +  5.100  =  1103-51.     BorzeUui.) 

The  reactions  of  this  acid  favour  the  supposition  that  it  is  a  com- 
pound of  hyposulphurous  and  sulphuric  acid  (S^O^  SO'). 

Combinations,    a.  With  Water.    Aqueous  Trithionic  acid. 

Preparation.  A  saturated  solution  of  bisulphite  of  potassa  is  heated 
with  flowers  of  sulphur  in  a  flask  for  three  or  four  days,  till  the  yellow 
colour  which  the  liquid  first  assumes  has  disappeared.  The  heat  must  not 
be  raised  to  the  boiling  point,  for  the  compound  would  then  be  destroyed. 
Sulphurous  acid  is  evolved  and  trithionate  of  potassa  is  formed  together 
with  small  quantities  of  sulphate  and  hyposulphite.  The  solution  filtered 
hot  bocomes  turbid  on  cooling  from  deposition  of  sulphur,  and  yields 
crystals  of  trithionate  of  potassa  mixed  with  sulphur  and  with  a  small 
quantity  of  sulphate :  they  may  be  obtained  in  a  state  of  purity  by  dis- 
solving them  in  the  smallest  possible  quantity  of  tepid  water,  then  filtering 
and  cooling  the  solution.  (Langlois.)  According  to  Pelouze,  the  simultaneous 
formation  of  hyposulphite  of  potassa  is  essential  to  the  process,— but  that 
of  sulphate  takes  place  merely  in  consequence  of  the  heat  becoming  too 
great,  whereby  the  trithionate  of  potassa  is  decomposed.  According  to 
this  view,  the  process  may  be  represented  by  the  following  equation: — 

3  (KO,  2SO«)  +  2S  =  2  (KO,  8*0»)  +  (KO,  S"0*.) 


TRITHIONIC  ACID,  167 

On  satorating  oold  water  with  tKe  potash-fialt  thus  obtained — adding 
to  the  solntioDy  in  small  portions  at  a  time,  the  quantity  of  tartaric,  or 
better,  of  perchloric  acid  required  to  precipitate  the  base— and  filtering, 
the  acid  is  obtained  in  the  state  of  aqueous  solution.  This  solution  maj 
be  concentrated  by  eyaporation  at  a  gentle  heat,  or  with  greater  security, 
in  vacuo  over  oil  of  vitriol;  but  it  is  thereby  rendered  more  liable  to 
decomposition.  (Langlois.) 

The  aqueous  solution  of  trithionic  acid  is  a  transparent  and  colourless 
liquid,  of  somewhat  syrupy  consistence  when  highly  concentrated;  not 
very  corrosive,  inodorous,  and  of  a  sour  and  somewhat  harsh  and  bitter 
taste.  ^Langlois.) 

It  IS  perfectly  pure  only  when  newly  prepared,  being  resolved,  gra« 
dually  at  ordinary  temperatures,  and  quickly  at  80^,  into  sulphur  which 
precipitates,  sulphurous  acid  which  escapes  as  gas,  and  sulphuric  acid 
which  remains  in  solution.  Only  the  dilute  solution  can  be  preserved. 
By  nitric  acid,  it  is  immediately  converted  into  sulphuric  acid,  with  evolu- 
tion of  nitric  oxide  and  precipitation  of  sulphur.  Chloric  acid  also  con- 
verts it  into  sulphuric  acia,*with  separation  of  sulphur  and  chlorine.  lodio 
acid  exerts  a  similar  action.  Perchloric  and  hydrochloric  acids  have  no 
effect  upon  it,  and  oil  of  vitriol  decomposes  it  merely  in  consequence  of 
the  rise  of  temperature  which  it  occasions.  (Langlois.) 

IT  When  this  acid  is  boiled  with  caustic  potash,  hyposulphite  and  sul- 
phate of  potassa  are  formed,  but  no  sulphide  of  potassium  (S'O'  =  SO*  + 
SH)') ;  the  addition  of  acetate  of  lead  does  not  give  a  black  precipitate. 
Sulphate  of  copper  in  excess  decomposes  the  acid  completely,  on  boiling, 
a  precipitate  of  sulphide  of  copper  being  formed.  Nitrate  of  mercuroui 
oxide  gives  a  black  precipitate  of  disulphide  of  mercury ;  Chloride  ofmer^ 
eurtfy  a  perfectly  white  precipitate  which  is  a  compound  of  sulphide  and 
chloride  of  mercury  without  free  sulphur ;  Cyanide  of  mercury  gradually 
forms  a  yellow  precipitate  blackening  slowly  in  the  cold,  rapidly  on  boil- 
ing; Nitrate  ofnlver,  a  perfectly  white  precipitate  which  quickly  blackens. 
With  ammoniacal  solutions  of  nitrate  of  silver  or  cyanide  of  mercury  tri- 
thionic acid  behaves  just  like  tetrathionic  acid  (p.  166,  Kessler).  Itsl)eha- 
viour  with  potassa,  sulphate  of  copper,  nitrate  ot  mercurous  oxide,  chloride 
of  mercury,  and  nitrate  of  silver  distinguishes  it  both  from  pentathlon io 
and  from  tetrathionic  acid :  from  the  former  it  is  likewise  distinguished 
by  its  behaviour  with  ammoniacal  solution  of  silver  or  of  cyanide  of 
mercuy.  IT 

6.  With  Salifiable  Bases*  Among  the  Trithionates,  the  potash-salt  is 
the  only  one  that  is  known  with  any  degree  of  accuracy.  It  is  decomposed 
at  a  red  heat  into  one  atom  of  sulphur,  one  atom  of  sulphurous  acid,  and 
one  atom  of  sulphate  of  potassa.  (Langlois.) 

KO,  S^'O*  =  KO,  SO»  +  S0«  +  S. 
Its  solution  is  resolved  on  boiling  into  sulphate  of  potassa,  sulphurous  acid, 
and  sulphur.  (Pelouze.)  In  the  circuit  of  the  voltaic  battery,  it  yields 
bisulphate  of  potassa  at  the  positive  pole.  Chlorine  gas  passed  through 
this  solution  converts  the  acid  into  sulphuric  acid.  Nitrate  acid  acts  vio^ 
lently  upon  it,  evolving  nitric  oxide  and  precipitating  sulphur.  Oil  of 
vitriol  added  to  it  causes  a  rise  of  temperature,  precipitating  sulphur  and 
eyolving  sulphurous  acid.  This  salt  is  not  decomposed  by  hydrochloric 
acid,  even  when  concentrated,  nor  by  chloric  or  iodic  acid.  The  aqueous 
solution  of  the  potash-salt  decolorizes  sulphate  of  manganic  oxide,  but  does 
not  at  ordinary  temperatures  precipitate  the  salts  of  baryta,  strontia,  lime, 
magnesia,  alumina,  uranic  oxide,  oxide  of  lead,  oxide  of  zinc,  or  of  the 


168  SULPHUR. 

protoxides  of  cobalt,  nickel,  and  copper.  It  decomposes  baryta-salts  on 
tbe  application  of  heat,  sulphate  of  baryta  being  formed.  (Pelonze.) 
With  mercarons  salts  it  gives  a  black  precipitate  of  sulphide  of  mercury.; 
with  mercuric  salts  a  white  precipitate  of  sulphate  of  mercurous  oxide ; 
and  with  nitrate  of  silver  a  yellowish-white  precipitate,  which  quickly  turns 
black,  in  consequence  of  the  formation  of  sulphide  of  silver.  (Langlois.) 
IT  Trithionate  of  baryta  is  obtained  in  shining  laminsd  by  saturating  the 
acid  with  carbonate  of  baryta,  and  adding  alcohol  to  the  liquid.  The  solu- 
tion of  this  salt  is  easily  decomposed,  with  separation  of  sulphate  of  baryta. 
The  crystals  are  composed  of  BaO,  S'O*  +  2H0.  ^   ^     ^ 

At  the  commencement  of  his  investigation  of  trithionic  acid,  and  before 
he  had  convinced  himself  of  it49  peculiar  nature,  Langlois  thought  that  he 
was  dealing  with  hyposulphurous  acid.  At  the  same  time,  Persoz  (J. 
Chem.  Med.  16,  383)  was  endeavouring  to  isolate  hyposulphurous  acid. 
His  process  was  as  follows : — He  precipitated  the  potash-eolt  (the  mode 
of  preparing  it  is  not  given)  by  nitrate  of  lead,  washed  the  precipitate, 
diffused  it  through  water,  decomposed  it  with  hydrosulphuric  acid,  and 
evaporated  the  filtrate,  which  deposited  bat  little  sulphur,  either  by  a 
gentle  heat  or  in  vacuo.  In  this  manner,  he  obtained  a  transparent  colour- 
less liquid,  which  reddened  litmus  strongly,  and  had  a  density  of  about 
2  000.  When  heated,  it  was  resolved  into  sulphuric  acid  and  sulphur.  It 
was  oxidized,  with  separation  of  sulphur,  by  nitric,  chloric,  and  hypochlo- 
rous  acids ;  it  was  also  decomposed  by  oil  of  vitriol,  with  precipitation  of 
sulphur,  and  precipitated  protosulphide  of  tin  from  an  aqueous  solution  of 
the  protochloride,  on  the  application  of  heat.  The  acid  of  Persoz  is  per* 
haps  also  trithionic  acid:  but  trithionate  of  potassa  does  not  precipi* 
tate  lead-salts.  Can  it  be  that  hyposulphite  of  lead  was  first  precipi- 
tated, and  that  trithionic  acid  was  formed  from  it  by  the  subsequent 
treatment  1 


IT  The  three  acids  just  described  are  included  under  the  general  name 
of  Folt/thionic  acids,  from  their  containing  more  than  one  atom  of  sulphur. 
The  hyposulphurous  and  hyposulphuric  acids,  S'O*  and  S'O*,  properly 
belong  to  the  same  series,  and  may  be  included  in  it  with  the  respective 
appellations  of  Dithionotis  and  Diihionic  acid;  but  the  names  by  which 
they  have  hitherto  been  distinguished  are  too  well  established  to  be  easily 
laid  aside.  Two  other  acids,  having  the  formulte  S*0'  and  S*0^  were  also 
asserted  by  Plessy  (iT.  Ann.  Chim,  Fhyn,  20,  162)  to  be  formed  by  the 
action  of  hydrated  sulphurous  acid  on  the  chlorides  of  sulphur;  but 
Fordos  &  Gelis  have  shown  that  these  supposed  new  acids  are  merely 
mixtures  of  the  diflerent  acids  of  the  polythionic  series  above  described.  IT 


E.    Sulphurous  Acid.    SO'. 

Imperfect  Sulphuric  acid;  Volatile,  pklogisticaied  Vitriolic  add;  Sckwef- 
lige  Saure,  Acide  sulfureux,  Addum  sidfuromm,  Acidum  Vitrioli 
phlogisticatum; — and  in  the  gaseous  state  :  SvZphurous  acid  gas. 
Sulphuric  acid gtu,  VUriolated  air,  Schwefiigsaures,  SchwefelsauresGas, 
Vitriolsaure  Luft,  Gas  acide  svlfureux,  Gas  acidum  sulphurosum. 

Occurrence  in  nature.     In  the  neighbourhood  of  volcanos,  both  in  the 
gaseous  state,  and  in  springs. 


SULPHUROUS  ACID.  169 

Formation.  1.  In  the  burning  of  snlphnr.  Sulphur  takes  fire  at 
260^,  according  to  Dalton,  at  294°,  according  to  Thomson,  and  bums  with 
a  blue  flame  in  air,  but  with  a  brilliant  violet  flame  in  oxygen  gas.  The 
oxygen  consnmed  is  replaced  by  sulphurous  acid  gas  occupying  almost 
exactly  the  same  volume.  (H.  Davy.) — 2.  When  sulphur  is  heated  with 
the  oxides  of  manganese,  zinc,  lead,  mercury,  and  other  metals. — 3.  On 
bringing  chloride  of  sulphur  in  contact  with  water. — 4.  In  the  decompo- 
sition of  hyposulphurous,  pentathionic,  tetrathionic,  and  trithionic  acid. — 
5.  In  the  decomposition  of  hyposulphurio  acid  by  heat. — 6.  On  heating 
concentrated  sulphuric  acid  with  many  metals,  or  with  charcoal  or  organic 
substances. 

Preparation  of  the  Gas.  1 .  Oil  of  vitriol  is  heated  with  one»third  of 
its  weight  of  copper,  or  its  own  weight  of  mercury,  till  the  mass  becomes 
solid.  {Scheme  23.)  The  gas  must  be  passed  through  a  Woulfe's  bottle 
containing  water,  in  order  to  arrest  sulphuric  acid,  mercury,  &c.,  which 
may  be  carried  over  with  it. — 2.  By  heating  oil  of  vitriol  with  charcoal 
or  wood-shavings  :  e.  g.,  according  to  Kuezaurek,  a  stiff  mixture  of  oil  of 
vitriol  and  charcoal  powder. — The  gas  prepared  by  this  method  is  conta- 
minated with  carbonic  acid. — 3.  By  heating  1  part  of  sulphur  with  7  or  8 
parts  of  manganese.  (Berthier.)  The  gas  thus  obtained  is  mixed  with 
sulphur-vapour,  oxygen  gas,  and  frequently  also  with  carbonic  acid  gas. 
(Marchand.) — 4.  A  mixture  of  1  part  sulphur  and  3  parts  black  oxide  of 
copper  is  placed  in  a  tube  and  covered  with  a  layer  of  pure  oxide ;  the 
latter  is  then  heated  first,  and  afterwards  the  mixture.  (Marchand.  Pogg. 
42,  144.) — 5.  By  burning  sulphur  in  the  air.  For  this  purpose,  Brunner's 
aspirator  (II.  34)  may  be  used.  The  sulphurous  acid  thus  produced  is 
mixed  with  the  nitrogen  of  the  air  and  a  small  quantity  of  oxygen.  The 
first  and  fourth  methods  yield  the  purest  gas.  The  gas  is  collected  over 
mercuiy.  If  it  be  wanted  free  from  moisture,  it  must  be  previously  passed 
through  a  tube  filled  with  chloride  of  calcium. 

Preparation  of  the  Liquid  Add,  1.  Faraday  pumps  the  dry  gas  into 
a  tube  previously  exhausted  of  air  and  cooled,  till  a  pressure  of  3  to  5 
atmospheres  is  attained. — 2.  Bussy  passes  the  gas,  prepared  in  the  flask  a 
{App.  45),  by  method  1,  first  through  a  Woulfe's  bottle  h  surrounded  with 
ice,  in  which  the  greater  part  of  the  watery  vapour  is  condensed — .then 
through  a  chloride  of  calcium  tube  e,  by  which  the  rest  of  the  moisture  is 
retained — and  lastly  into  a  email  Woulfe's  bottle  dy  surrounded  with  a 
freezing  mixture  consisting  of  equal  weights  of  ice  and  salt,  and  fitted  with 
a  bent  tube  which  serves  to  convey  the  air  of  the  apparatus  and  the  uncon- 
densed  gas  under  mercury. — 3.  Wach  (Schtp.  50,  26)  distils  in  a  long  glass 
tube  sealed  at  both  ends  and  somewhat  bent,  a  mixture  of  1  part  sulphur 
and  5  parts  anhydrous  sulphuric  acid,  applying  a  very  gentle  heat  to 
the  arm  of  the  tube  containing  the  materials,  and  keeping  the  empty  arm 
cool  by  means  of  a  freezing  mixture;  the  acid  which  passes  over 
must  be  several  times  poured  back  again  to  free  it  from  sulphuric  acid. 
Bussy's  method  is  the  most  convenient.  The  acid  is  preserved  either 
in  strong  well-stopped  bottles  at  the  temperature  of  0°,  or  else  in  sealed 
tubes. 

Preparation  of  the  Solid  acid.  1.  Bussy  brings  the  liquid  acid  to 
rapid  evaporation  under  the  exhausted  receiver  of  the  air-pump.  Part  of 
it  solidifies  in  the  form  of  white  flakes. — 2.  Mitchell  (Ann.  Phai^m.  37, 
356)  surrounds  the  vessel  containing  the  liquid  acid  with  a  mixture  of 
solid  carbonic  acid  and  ether. 


170  8ULPHUH. 

Properiiei  of  Solid  Sulphurous  acid.  Fonns  white  flakes*  (Bngsy.) 
Speoificuaily  heavier  than  the  liquid  acid.  Freezing  point  about — 79^  G.^ 
or— 110°Fah.     (Mitchell.) 

Properties  of  the  liquid  dcid.  Colourless,  transparent,  rery  thin  liquid. 
Sp.  gr.  1*42°  (Faraday),  1*45^  (Bussy).  Refractive  power  about  equal  to 
that  of  water  (Faraday),  or  somewhat  greater.  (De  la  Rive.)  Boils  at 
—10°  C.  (+14^  F.)  under  the  ordinary  pressure  of  the  atmosphere 
(Faraday),  and  at  — 10-5°  (-|-  13-1°  F.)  under  a  pressure  of  29-3  inches. 
(Bunsen.)  This  liquid  in  passing  into  the  state  of  gas,  produces  intense 
cold,  thereby  cooling  itself  in  a  short  time  below  its  own  boiling  point,  so 
that  afterwards  the  vaporization  goes  on  more  slowly.  It  freezes  water 
on  which  it  is  poured. 

Properties  of  the  Gas,  Refracting  power,  tension,  and  specific  gravity 
(I.,  95,  261  and  279).  Colourless,  incombustible,  not  capable  of  support- 
ing the  combustion  of  other  bodies;  of  pungent,  suffocating  odour;  wholly 
irrespirable ;  reddens  litmus,  and  decolorizes  roses,  violets,  paper  dyed 
with  logwood,  &c.,  provided  water  is  present. 

Calculation. 


S 16  50  

20     ....  16  50  

49-968  

50*032  

..  53     

..  47     .... 

59 

41 

SO'   ....  32  100 

Snloliiir  vaDour 

100-000 

Vol.          Sp.  gr. 
1  .          6*6556 

100 
Vol. 

100 

Sp.gr. 
1-1093 

Oxygen  gas  

6  6-6558 

...  11093 

SalphuroTU  acid  gas      6  13-3114     =     1 2*2186 

(S0«  =  20117  +  2  .  100  =  401-17.    BerzeUus.) 

Decompositions.  1.  The  liquid  acid  does  not  conduct  the  electricity 
of  a  forty-pair  battery;  but  on  the  addition  of  water,  it  yields  sulphur  at 
the  positive  and  hydrogen  at  the  negative  pole.  (De  la  Rive.)  The  liquid 
acid  (quite  dry  1)  conducts  the  electricity  of  a  250-pair  battery  as  well 
as  a  metal,  and  evolves  oxygen  at  the  positive  pole,  whilst  at  the  negative 
pole  nothing  appears  at  first,  but  subsequently  sulphur  is  deposited. 
(Kemp,  N.  Ed.  J.  of  Nat.  and  Geograph.  Sc.  1,  27.)— 2.  When  the  gas 
in  a  moist  state  is  passed  through  a  red-hot  tube,  it  is  resolved  into  sul- 
phur and  concentrated  sulphuric  acid.  (Priestley;  Berthollet.) — 3.  When 
hydrogen  gas  and  sulphurous  acid  gas  are  passed  together  through  a  red- 
hot  tube,  water  is  formed  and  sulphur  deposited ;  and  when  sulphurous  acid 
gas  is  passed  through  a  tube  containing  ignited  charcoal,  carbonic  acid  is 
produced  and  sulphur  precipitated.  Phosphorus  gentlv  heated  does  not 
decompose  sulphurous  acid  gas.  (Fourcroy  &  Vau<juelin.)  Phosphorus 
kept  for  some  weeks  in  a  solution  of  sulphurous  acid  acquires  a  bright 
yellow  coating.  (Vogel,Junr.  t/.jpr.  Chem.  19,  294.) — 4.  With  phosphuretted 
hydrogen  at  ordinary  temperatures,  sulphurous  acid  gas  forms  water  and 
sulphide  of  phosphorus ;  similarly  with  hydrosulphuric  acid  gas,  it  yields 
water  and  sulphur ;  with  hydriodic  acid  gas,  water,  sulphur,  and  iodine ; 
and  with  hydrochloric  acid  gas,  water,  sulphur,  and  chlorine.  Aqueous 
phosphorous  acid  heated  with  aqueous  sulphurous  acid  yields  phosphoric 
and  hydrosulphuric  acid : 

3P0»  +  2S0»  +  2HO  =  3P0»  +  2HS; 

and  the  hydrosulphuric  acid  thus  formed  acts  upon  the  excess  of  sul- 
phurous acid  in  such  a  manner  as  to  form  water  and  sulphur.  (Wohler, 


SULPHUROUS  ACID.  I7l 

Ann.  Fharm.  39,  252.)  6.  Many  metals  heated  in  sulphiiroiis  acid  gas 
are  oonrerted — sometimes  with  evolation  of  light  and  heat — into  metallic 
oxides  and  snlphides.  Many  metals,  as  zinc,  tin,  and  iron,  abstract 
oxygen  from  aqueous  snlphurous  acid  and  conyert  it  into  hjposnlphuroas 
acid :  e»  g. 

2Zd  +  3SO«  -  ZnO,  8«0«  +  ZnO,  SO*. 

When  copper  is  immersed  in  the  aqueous  acid  at  ordinary  temperatures 
and  out  of  contact  of  air,  sulphide  and  sulphate  of  copper  are  formed. 
(Baruel,  Junr.  J.  Pharm.  20,  17.) 

2Cn  +  2S0*  =  CnS  +  CuO,  S0«. 

Zinc  immersed  in  an  aqueous  solution  of  sulphurous  acid  mixed  with 
dilute  sulphuric  or  hydrochloric  acid  causes  an  evolution  of  hydrosulphurio 
acid  gas ;  and  this,  when  the  quantity  of  sulphurous  acid  present  is  con* 
siderable,  may  give  rise  to  precipitation  of  sulphur. 

3ZnO  +;SO«  +  HO  +  3S0»  =  3  (ZnO,  80»)  +  HS. 

(Fordos  &  G61is,  J.  Pharm.  27, 730.)  See  also  Kone  (Poffg.  63,  245}, 
Fordos  4fe  G61is  J.  pr.  Chem.  31,  402),  Muspratt  {Ann,  Pharm.  5^,  259). 

C<mb%natvm8.  o.  With  Water,  a.  Crystallized  Sulphurous  add. 
Produced  in  the  form  of  delicate  white  laminsB  when  sulphurous  acid  gas 
not  perfectly  dry  is  cooled  by  means  of  a  freezing  mixture — and  likewise 
as  a  white  snow-like  mass  when  the  liquid  acid  evaporates  in  the  air. 
Contains  about  20  pts.  acid  and  80  pts.  water.  Remains  solid  till  raised 
to  between  4°  and  5°  C.  (40°  and  4 1*'  F.^;  but  above  that  temperature 
it  melts,  water  being  formed,  with  evolution  of  sulphurous  acid  gas. 
(De  la  Rive.) 

IT  Pierre  {N.  Ann.  Chim,  Phys.  23,  416)  has  obtained  the  crystallized 
hydrate  just  mentioned  by  passing  vapour  of  water,  together  with  a  large 
excess  of  sulphurous  acid  gas,  through  a  tube  cooled  to  between  •—  6°  and 
—  8*^  0.  The  crystals  were  produced  in  abundance,  but  they  were  con- 
fused and  opaque.  They  were  found  to  contain  SO^  llHO.  But  as 
these  crystals  had  been  formed  at  a  temperature  a  few  degrees  below  0°, 
it  seemed  probable  that  crystals  of  ice  might  be  associated  with  them ; 
indeed  their  appearance  was  in  favour  of  this  supposition.  To  obviate 
this  source  of  inaccuracy,  Pierre  endeavoured  to  form  the  crystals  by 
exposing  a  highly  concentrated  aqueous  solution  of  sulphurous  acid  for 
some  time  to  a  temperature  of  (f.  Groups  of  crystals  were  formed,  the 
primary  form  of  which  appeared  to  be  an  oblique,  rhombic  prism.  These 
crystals  fused  at  4°,  evolving  snlphurous  acid.  When  thrown  upon  a 
platinum  dish  heated  to  between  20°  and  25°,  they  made  a  hissing  noise 
like  water  thrown  upon  a  surface  at  a  dull-red  heat.  Their  composition 
was  found  to  be  : 

Calculated.  Found. 

SO«     28-35  '27-85  28'^i 

9HO  71-65  72-15  71-99 

Similar  results  have  been  obtained  by  Popping.  {J.  pr.  Chem,  44, 
255.)  % 

0.  Aqueous  soltUion  of  Sulphurous  acid,  otherwise  called  Spiritus 
StUphuris  per  Campanum.  When  liquid  sulphurous  acid  is  cautiously 
poured  into  ice-cold  water,  it  settles  at  the  bottom  and  forms  a  distinct 
stratum ;  but  if  a  rod  be  then  immersed  in  the  liquids  so  as  to  disturb 
them,  combination  takes  place,  attended  with  so  great  an  evolution  of 


172  SULPHUR. 

heat,  (which  is  further  increased  by  the  water  giving  up  its  lateut  heat 
and  being  converted  into  ice,)  that  the  liquid  boils  violently  and  gas  is 
evolved.  (Bussy.)  By  contact  with  a  piece  of  ice  also,  sulphurous  acid 
is  instantly  brought  to  a  state  of  ebullition.  (Faraday.)  According  to 
Fourcroy<fe  Vauquelin  {Orell.  Ann.  1800,  2,  307),  water  at  5°  absorbs 
one-seventh  of  its  weight  of  sulphurous  acid,  and  the  specific  gravity  of 
the  solution  is  1-020.  According  to  Priestley,  the  quantity  of  the  gas 
absorbed  by  water  at  ordinary  temperatures  is  only  -^  oi  its  weight; 
at  16^  according  to  Thomson,  -Jy  of  its  weight,  or  33  times  its  volume,  the 
specific  gravity  of  the  solution  being  1*0513  ;  according  to  Davy,  30  tinies 
— according  to  Dalton,  20  times — ^according  to  Saussure,  44  times  its 
volume,  at  18°.  According  to  BerthoUet,  the  specific  gravity  of  water 
saturated  with  sulphurous  acid  is  1'040.  The  combination  of  the  gas 
with  water  is  attended  with  a  slight  development  of  heat.  Ice  introduced 
into  the  gas  quickly  melts. 

The  liquid  is  colourless,  has  the  odour  of  burning  sulphur,  and  an 
acid,  drying  taste.  When  the  water  in  the  solution  freezes — ^which 
effect  takes  place  a  few  degrees  below  0° — the  cas  does  not  escape;  and 
only  a  portion  is  evolved  on  boiling,  unless  the  boiling  be  continued  for 
a  very  long  time.  When  the  solution  is  exposed  to  the  air,  part  of  the 
gas  escapes,  the  rest  remaining  in  the  form  of  sulphuric  acid.  The 
aqueous  acid  gives  with  hydrosnlphuric  acid,  after  a  while,  a  milk-white 
cloud,  and  with  selenious  acid,  a  red  cloud.  It  decolorizes  sulphate  of 
manganic  oxide,  and  hypermanganate  of  potassa,  and  precipitates  metallic 
gold  from  the  chloride.  The  smallest  quantity  of  sulphurous  acid  evolves 
sulphuretted  hydrogen  when  treated  with  zinc  and  hydrochloric  acid* 
(Fordos  &  Gelis,)— and  gives  a  blue  colour  to  paper  moistened  with  starch 
and  iodic  acid.  (Orfila.) 

6.  The  Sulphites,  or  salts  produced  by  the  combination  of  sulphurous 
acid  with  salifiable  bases  are  obtained  by  passing  sulphurous  acid  gas  into 
water  in  which  the  bases,  either  pure  or  in  the  state  of  carbonates,  are 
dissolved  or  diffused.  They  are  inodorous,  and  when  soluble,  have  a 
sharp,  brisk  flavour.  Monosulphite  of  potassa  or  soda  has  an  alkaline 
reaction,  while  the  corresponding  bi-salts  are  neutral.  The  sulphites  of 
the  fixed  alkalis,  sulphite  of  lead,  and  the  sulphites  of  some  of  the  other 
heavy  metallic  oxides  are  resolved  by  ignition  into  |  sulphate  and  \ 
sulphide :  e.  g, 

4  (PO,  S0«)  =  3PbO,  S03  +  PbS. 

Other  sulphites,  those  of  the  earths  for  instance,  ^ve  off  their  acid,  while  the 
base  remains  behind.     Most  of  the  heavy  metallic  sulphites,  when  heated  j 

with  charcoal,  hydrogen,  potassium,  sodium,  iron,  zinc,  tin,  manganese,  | 

or  antimony,  are  reduced  to  the  state  of  sulphides,  the  bodies  iust  men-  \ 

tioned  abstracting  oxygen  from  both  the  acid  and  the  metallic  oxide. 
The  alkaline  sulphites  in  the  state  of  solution  in  water  are  converted  by 
digestion  with  sulphur  into  hyposulphites  and  trithionates  :  small  quan- 
tities of  hydrosnlphuric  acid  or  of  an  alkaline  sulphide  likewise  convert  i 


*  Protochloride  of  tin  is  recommended  by  Wackenroder  as  the  best  reagent  for  de- 
tecting traces  of  sulphurous  acid.  The  solution  to  be  tested  is  to  be  acidulated  with 
hydrochloric  acid — ^mixed  with  solution  of  protochloride  of  tin — and  the  contaiDing  ves- 
sel covered  with  a  glass  plate,  to  the  under  surface  of  which  is  attached  a  piece  of  paper 
moistened  with  solution  of  acetate  of  lead.  If  sulphurous  acid  be  present,  or  any  of  the 
other  acids  of  sulphur  which  evolve  it  on  being  mixed  with  hydrochloric  add — sulphu- 
retted hydrogen  will  be  given  off,  and  will  blacken  the  paper.  (Phmrmae.  CetUralblatt, 
1846,  p.  615.)     [W.] 


I 


SULPHUROUS  ACID.  17^ 

tliem^  without  precipitation  of  sulphur  into  hjrposulphites ; — ^with  larger 
quantities  of  the  same  reagents^  the  conversion  is  accompanied  by  preci- 
pitation of  sulphur  (IT.,  160).  By  exposure  to  the  air,  especially  in  the 
moist  state — also  by  contact  with  nitric  oxide  gas,  excess  of  heated  nitric 
acid,  or  with  chlorme  water,  solution  of  hypochlorous  acid  or  its  salts, 
or  with  nitre  and  certain  heavy  metallic  oxides  in  a  state  of  fusion — the 
sulphites  take  up  an  additional  dose  of  oxygen,  and  are  converted  into 
sulphates,  their  neutrality  remaining  unaltered.  In  a  similar  manner,  the 
alkaline  sulphites  decolorize  manganate  of  potassa  mixed  with  sulphuric 
acid,  and  likewise  the  salts  of  sesqui- oxide  of  iron,  which  are  first  reddened 
by  them  and  then  converted  into  salts  of  protoxide  of  iron.  The  alkaline 
sulphites  likewise  precipitate  selenium,  in  the  form  of  a  red  powder,  from 
selenious  acid  mixed  with  hydrochloric  acid, — and  tellurium,  as  a  black 
powder,  from  solution  of  chloride  of  tellurium ; — throw  down  light-brown 
sulphite  of  suboxide  of  copper  from  salts  of  protoxide  of  copper,  on  boiling, 
— and  metallic  gold  from  cnloride  of  gold,  on  the  addition  of  hydrochloric 
acid.  With  nitrate  of  silver,  they  give  a  precipitate  which  is  white  at 
first,  but  changes  slowly  in  the  cold,  and  quickly  on  boiling,  into  a  briN 
liant  specular  coating  of  metallic  silver.  From  protochloride  of  tin 
dissolved  in  hydrochloric  acid^  the  smallest  quantity  of  an  alkaline  sul- 
phite gradually  throws  down  a  brown  precipitate  of  protosulphide  of  tin. 

The  sulphites  are  not  decomposed  by  carbonic  or  boracic  acid ;  but 
they  are  decomposed  by  phosphorous,  sulphuric,  hydrochloric,  arsenic  acid, 
&c.^  without  precipitation  of  sulphur :  if  there  is  not  much  water  present, 
the  sulphurous  acid  escapes  with  efiervescence. 

Among  the  simple  sulphites,  only  the  ammonia,  potassa,  soda,  and 
Hthia  salts  are  soluble  in  water.  Hence  a  solution  of  either  of  these 
salts  gives  with  the  earthy  alkalis,  earths,  and  heavy  metallic  oxides, 
precipitates  which  are  soluble  in  dilute  hydrochloric  or  nitric  acid.  If 
however  the  precipitate  of  sulphite  of  baryta  or  sulphite  of  lead  is  boiled 
with  nitric  acid,  an  insoluble  precipitate  of  the  corresponding  sulphate 
is  formed.     The  acid  sulphites  are  all  soluble  in  water. 

IT  Dr.  Muspratt  has  made  an  elaborate  investigation  of  the  salts  of 
sulphurous  acid  (Ann,  Pharm,  50,  259) — by  which  he  has  shown  that  a 
great  number  of  these  salts  are  precisely  analogous  in  composition  to  the 
corresponding  carbonates,  and  are  moreover  isomorphous  with  them.  The 
following  table  exhibits  this  analogy  of  composition  in  the  two  classes  of 
salts,  in  those  cases  in  which  it  has  been  observed : 


8H0 


Sulphites. 
KO,  SO«  +  2H0 

Carb<mates» 

KO,CO«  +  2HO 

KO,SO«  +  HO,SO« 

KO,CO»  +  HO,CO« 

NaO,  SO«  +  lOHO 

NaO,CO«  +  lOHO 

NaO,SO«  +  HO,  SO 

NaO,  C0«  +  HO,  C0« 

NaO,SO«  +  HO,SO»,   +  8HO 

NaO,CO«    +H0,C0«  + 

BaO,  SO* 

BaO,  CO* 

SrO,  SO 

SrO,  CO* 

MgO,SO"  +  3H0 

MgO,  CO«  +  3HO 

MnO,  SO«  +  2HO 

MnO,CO«  +  2H0 

PbO,SO« 

PbO,  C0« 

AgO,SO« 

AgO,CO«. 

Many  of  the  sulphites  which  are  insoluble  in  water  are  soluble  in 
aqueous  solution  of  sulphurous  acid;  e.  g.  the  sulphites  of  baryta,  strontia, 
and  lime,  another  property  in  which  these  salts  resemble  the  carbonates.  IT 

c.  Sulphurous  acia  gas  is  absorbed  by  alcohol  and  other  organic 
liquids. 


174  BULPHUR. 


P.    Hyposulphubio  Acid.    SH>*. 

JXthionie  acid,  CnierschwefeUaure,  Acide  hypotulfurique,  Acidum  hypo* 

stUphuricum. 

FamuxUan.  ThLs  acid  is  produced  on  bringing  aqaeonfl  snlphnroiifl 
acid  in  contact  with  peroxide  of  manganese  fnot  with  brown  peroxide  of 
lead  or  peroxide  of  barium).  Oap-Lusmc,  (Scheme  106.) 

MnO»  +  2SO*  =  MnO,S«0». 

When  1  part  of  powdered  mauffanese  is  diffused  through  5  ports  of  water, 
and  sulphurous  acid  gas  passed  through  the  liquid,  the  temperature  rises 
from  16°  to  50°,  and  hjdrated  manganic  oxide  (Mn*0',  HO)  separates  in 
the  form  of  a  brown  powder.  Sulphate  of  manganese  is  always  produced 
simultaneously  with  the  hyposulphate.  (MnO*+SO*  =  MnO,SO*.) 
The  quantity  of  sulphuric  acid  thus  formed  varies  from  137  to  370  parts, 
for  every  1000  parts  of  hyposulphuric  acid  produced;  it  appears  to  be 
greater  as  the  temperature  of  the  liquid  is  higher,  and  the  manganese 
less  finely  pounded.  The  presence  of  hydrated  manganic  oxide  in  the 
manganese  may  give  rise  to  the  production  of  sulphate  and  likewise  of 
sulphite  of  manganous  oxide; 

Mn«0»  +  2S0««  MnO,  SO'  +  MiiO,SO*; 
the  native  oxide  is,  however,  difficult  of  solution.     Hyper-manganic  acid 
likewise  forms  hyposulphate  of  manganous  oxide  by  contact  with  aqueous 
sulphurous  acid.     Anhydrous  liquid  sulphurous  acid  has  no  action   on 
manganese.  (Heeren.) 

Hyposulphuric  acid  does  not  appear  to  be  formed  when  sulphurous 
acid  gas  is  passed  through  oil  of  vitriol  strongly  cooled.  In  this  case, 
according  to  Fourcroy  &  Vauquelin,  a  frozen  mass  is  produced,  which,  on 
thawing,  evolves  sulphurous  acid  gas.  If  oil  of  vitriol  be  agitated  in  the 
cold  with  anhydrous  liquid  sulphurous  acid,  only  a  small  quantity  of  the 
latter  mixes  with  the  oil  of  vitriol,  diminishing  its  specific  e^ravity,  and 
imparting  to  it  the  odour  of  sulphurous  acid,  but  without  making  it  fume ; 
the  greater  part  of  the  sulphurous  acid  rises  to  the  top  of  the  oil  of 
vitriol,  and  forms  a  distinct  layer  above  it.  (Bussy.)  A  peculiar  com* 
pound  of  sulphurous  acid  with  anhydrous  sulphuric  acid  will  be  described 
under  the  head  of  Sulphuric  Acid, 

Hyposulphuric  acid  is  not  known  to  exist  in  the  separate  state. 


Calculation. 

Or: 

2S... 

32  

.  44.44 

S0«  .... 

....  32  .... 

....  44-44 

50... 

40  

55-56 

SO'  .... 

....  40  .... 

....  55-56 

S«0» 72  100-00  S»0«     ....  72  100*00 

(S'O*  =  2  .  201-17  +  6  .  100  =  902-34.    BeraeUus.) 

Combinations,    a.  With  Water. 

a.  Hydrate  of  Hyposulphuric  Acid,  Sulphurous  acid  gas  is  passed 
through  water  in  which  powdered  manganese  is  suspended.  Sulphate 
and  hyposulphate  of  manganous  oxide  are  then  produced ;  the  manganous 
oxide  and  the  sulphuric  acid  are  precipitated  by  excess  of  baryta  water — 
the  liquid  is  filtered — ^and  the  excess  of  baryta  separated  by  passing 
carbonic  acid  ps  through  the  liquid,  and  subsequent  boiling.  The 
hyposulphate  of  baryta  is  next  to  be  purified  by  evaporation  and  crys- 


HYPOSULPHURIC  ACID.  175 

talliiation — the  crystals  dissolved  in  water — the  harjrta  precipitated  by 
sulphuric  acid  cautiously  added  in  the  exact  proportion  required — and 
lajstly,  the  filtrate  concentrated,  first  by  warming,  and  afterwards  by 
eyaporation  in  vaono  oyer  sulphuric  acid,  till  it  attains  a  specific  gravity 
of  1-347.  (Gfay-Lussac.)  Heeren  uses  1  part  of  yery  finely  pounded 
manganese  to  5  parts  of  waters—precipitates  the  filtrate,  not  by  baryta 
water,  but  by  solution  of  hydrosulphate  of  baryta — decomposes  the 
excess  of  this  reagent  bj^  agitating  the  liquid  with  carbonic  acid  gas — 
filters — boils  the  solution  in  order  to  drive  off  the  sulphuretted  hydrogen 
and  carbonic  acid,  and  precipitates  the  carbonate  of  baryta — ^then  filters 
the  liquid,  and  evaporates  to  the  crystallizing  point,  &c.  &c. 

The  hydrate  of  hyposulphuric  acid  is  a  transparent  and  colourless 
liquid,  inodorous,  and  of  strongly  acid  taste.  By  further  evaporation  in 
vacuo,  or  by  being  heated  to  100^,  it  is  decomposed  into  sulphurous  acid, 
which  escapes,  and  sulphuric  acid,  which  remains  behind.  (Gay-Lussac.) 
When  exposed  to  the  air,  it  is  slowly  converted  into  sulphuric  acid.  It 
is  not  oxidated  in  the  cold  by  strong  nitric  acid,  chlorine  water,  or  sul- 
phate of  manganic  oxide  (Gay-Lussac^;  nor  yet  by  aqueous  hypochlo- 
rous  acid.  (Balard.)  It  does  not  take  oxygen  from  aqueous  hyper- 
manganic  acid,  peroxide  of  lead,  or  the  oxides  of  mercury,  silver,  gold, 
and  platinum,  dissolved  in  acids;  neither  does  it  decompose  hydrosnl- 
phuric  or  hydriodic  acid  dissolved  in  water.  (Heeren.)  When  dilute, 
it  dissolves  zinc  (and  iron,  according  to  Heeren),  with  evolution  of 
hydrogen,  but  without  decomposition  of  the  acid  itself.  (Gay-Lussac.) 

0.  The  acid  is  miscible  with  larger  quantities  of  water. 

b.  The  salts  produced  by  the  union  of  this  acid  with  salifiable  bases 
are  called  ffyposulphates :  in  the  normal  state  they  contain  2  atoms  of 
sulphur  and  5  atoms  of  oxygen  for  every  atom  of  base.  When  heated-— 
sometimes  even  at  100° — they  evolve  1  atom  of  sulphurous  acid  and 
leave  1  atom  of  neutral  sulphate.  In  the  state  of  aqueous  solution,  they 
are  not  oxidized  at  ordinary  temperatures,  either  by  exposure  to  the  air, 
or  by  nitric  acid,  chlorine,  hypochlorous  acid,  hypermanganic  acid, 
peroxide  of  lead,  or  by  the  oxides  of  mercury,  silver,  gold,  and  platinum 
dissolved  in  acids.  But  at  a  boiling  heat,  they  are  oxidized  by  nitric 
acid  or  chlorine,  2  atoms  of  sulphuric  acid  being  produced  for  each  atom 
of  base.  In  the  solid  state,  they  are  decomposed  by  oil  of  vitriol,  even 
at  ordinary  temperatures,  sulphurous  acid  escaping  with  violent  effer- 
vescence. But  in  the  state  of  aqueous  solution,  they  are  not  decomposed 
by  sulphuric  or  hydrochloric  acid  till  the  liquid  is  boiled,  and  then  they 
are  resolved  into  sulphurous  acid  and  a  sulphate,  without  deposition 
of  sulphur.  In  consequence  of  this  evolution  of  sulphurous  acid,  a 
solution  of  a  hyposulphate  boiled  for  a  few  minutes  with  either  of  the 
acids  just  mentioned,  decolorizes  hypermanganic  acid,  precipitates  sulphur 
from  hydrosulphuric  acid,  and  gold  from  the  chloride  of  that  metal.  All 
hyposulphates  are  soluble  in  water.  (Gay-Lussac;  Heeren;  H.  Rose.) 

G.    Sulphuric  Acid.    SO*. 

Vitriolic  acid,  Perfect  Sulphuric  add,  Sekwefdsaure,  Acide  Sulfurique, 
Aeidum  9ulphuricum,  Acidum  vitrioUcum, 

This  acid  probably  exists  combined  with  water  in  certain  volcanic 
springs:  it  is  also  found  in  large  quantities,  both  in  the  organic  and 
inorganic  kingdoms,  in  combination  with  ammonia,  potassa,  sock,  baryta, 
strontia,  lime,  magnesia,  alumina,  the  protoxide  and  sesqui-oxide  of  ura- 


176  SULPHUR. 

nium^  the  oxides  of  cobalt,  zinc^  and  lea<l,  the  protoxide  and  sesqui-oxide 
of  iron,  and  the  protoxide  of  copper. 

Formation,     1.  From  Sulphur,     a.  In  well- washed  flowers  of  sulphur 
exposed  to  the  air  for  several  weeks,  a  certain  quantity  of  sulphuric  acid 
is  gradually  formed.  (John,  Schw.    14,    417;    Wagenmann,  Pogg,   24, 
601.)     Milk  of  sulphur  kept  in  a  dry  state  for  18  jears  was  found  by 
Wackenroder  to  be  free  from  sulphuric  acid.  {N,  Br.  Arch,  26,  180.) 
5.  Bj  the  action  of  chlorine  water,  hjpochlorous  acid  and  its  salts,  bj 
nitric  acid,  aqua  regia,  by  a  mixture  of  nitric  acid  and  chlorate  of  potassa, 
and,  at  a  red  neat,  by  alkaline  iodates,  hyperiodates,  bromates,  chlorates, 
perchlorates,  nitrites  and  nitrates. — 2.  From  pentathionic,  tetrathionic,  and 
trithionic  acid,  by  eleyation  of  temperature,  or  by  the  action  of  chlorine 
on  nitric  acid. — 3.  From  sulphurous  acid.     a.  A  dry  mixture  of  two 
measures  of  sulphurous  acid  gas  and  one  measure  of  oxygen  remains 
unaltered :  but,  if  water  be  present,  a  very  gradual  condensation  takes  place, 
and  sulphuric  acid  is  produced; — ^in  contact  with  red-hot  platinum,  especially 
if  water  be  present,  the  effect  takes  place  very  quickly.  (Per.  Phillips,  Pogg. 
24,  610.)     If  the  undried  mixture  of  sulphurous  acid  and  oxygen  or  at- 
mospheric air  be  passed  through  a  tube  kept  at  a  low  red  heat,  and  con- 
taining spongy  platinum  or  platinum  wire,  nearly  all'the  sulphurous  acid  is 
converted  into  oil  of  vitriol.  (Phillips ;  Magnus.)     If  the  tube  contains 
pieces  of  glass  instead  of  platinum,  the  quantity  of  sulphuric  produced  is 
small;  and  if  it  be  empty,  still  less.  (Magnus,  Pogg.  24,  610.^     Platinum- 
black  dried  in  the  air  converts  the  mixture  of  sulphurous  acia  and  oxygen 
into  fuming  oil  of  vitriol.  (Dobereiner,  Pogg.  24,  609.) — 6.  When  sulphur- 
ous acid  gas  is  mixed  with  oxygen  (or  air),  nitric  oxide,  and  vapour  of 
water,  the  nitric  oxide  first  takes  up  oxygen  and  is  converted  into  hyponi- 
tric  acid,  and  then  gives  it  up  to  the  sulphurous  acid,  which  is  thereby  con- 
verted into  sulphuric  acid.     (For  a  more  exact  explanation  of  this  reaction, 
on  which  the  preparation  of  common  oil  of  vitriol  depends,  see  Nitrogen  and 
Svlphur.) — c.  By  chlorine- water,  hypochlorous  acid  and  its  salts,  nitric 
acid,  peroxide  of  hydrogen,  and  the  peroxides  of  certain  metals.     In  the 
last-mentioned  case,  the  sulphuric  acid  formed  by  the  oxidation  combines 
with  the  salifiable  base  produced  by  the  reduction  of  the  peroxide. — 4.  From 
hyposuiphuric  acid.     a.  By  simply  heating  the  acid.     6.  By  heating  it 
together  with  nitric  acid. — 5.  From  hydrosulphuric  acid,  and  from  metulic 
fiuTphides,  hyposulphites,  pentathionates,  tetrathionates,  trithionates,  sul- 
phites, and  hyposulphates.  {q.  v.) 

Preparation  of  Anhydrous  Sulphuric  acid. — Fuming  oil  of  vitriol  is 
heated  in  a  retort,  the  neck  of  which  passes  air-tight  into  a  perfectly  dry 
receiver  surrounded  with  ice.  No  luting  or  paper  must  be  used  in  making 
the  connexion.  Anhydrous  sulphuric  acid  distils  over  first,  and  is  fol- 
lowed by  hydrated  acid:  hence  the  receiver  must  be  changed  after  a 
while.  Anhydrous  sulphate  of  antimony  or  of  bismuth  may  likewise  be 
used.  (Graham,  Lehrh.  2,  140.)  By  mixing  three  parts  of  dry  sulphate 
of  soda  with  two  parts  of  oil  of  vitriol,  heating  the  mixture  to  commencing 
redness,  and  till  it  ceases  to  boil — pounding  it  up  quickly  after  cooling 
—and  igniting  it  in  a  porcelain  retort,  a  nearly  anhydrous  acid  is  ob- 
tained in  brittle  tubular  masses.  (Bcrzelius.) 

^  According  to  the  experiments  of  Barreswil  {Compt.  Rend.  25,  80), 
anhydrous  sulphuric  acid  may  be  obtained  by  distilling  common  oil  of 
vitriol  with  anhydrous  phosphoric  acid.  ^ 


SULPHURIC  ACID.  177 

Properties.  Slender  needles  arranged  in  feathery  and  etar-shaped 
groups  and  forming  a  white,  opaque,  asbestos-like  mass.  Tough  and  dif- 
ficult to  cut.  (F.  C.  Voffel.)  Sp.  gr.  at  13«= 1-9546  (Morveau),  and  in 
the  liquid  state  at  20^=:1'97.  (Bussy.)  Puses  between  12'*  and  19** 
(F.  C.  Vogel),  between  22*  and  24'*  (Fischer),  at  25°,  or  a  little  below 
(Bussy), — ^forming  a  liquid  which,  according  to  Bussy,  is  thinner  than 
common  oil  of  vitriol,  and  probably  colourless  when  pure,  but  generally 
has  a  brown  colour,  possibly  arising  from  a  small  quantity  of  organic 
matter  introduced  in  the  A>rm  of  dust  and  decomposed  by  the  acid. 
According  to  Wach,  the  acid  when  dried  to  the  utmost  possible  extent, 
assumes  at  62*5°  the  appearance  of  moistened  cotton,  and  melts  at  100°  to 
a  colourless  liquid.  It  boils  between  52°  and  56°.  (Fischer,  Po^^.  16, 
119.)  [These  two  statements  contradict  each  other.]  The  vapour  is 
colourless;  its  specific  gravity  has  already  been  given  (I.,  279).  Exposed 
to  the  air  at  ordinary  temperatures,  the  acid  forms  thick,  white,  suffocating 
fumes.  It  may  be  held  for  a  while  between  the  dry  fingers,  but  soon 
produces  a  penetrating  sensation.  (F.  C.  Vogel.)  Hisses  violently  when 
thrown  into  water.  Produces  dense  white  fumes  in  the  air.  Chars 
wood,  paper,  and  many  other  organic  bodies  very  rapidly.  Very  corro- 
sive and  poisonous ;  its  solution  in  water  has  a  strongly  acid  taste,  and 
reddens  litmus,  whereas  the  anhydrous  acid  does  not  redden  dry  litmus 
paper.  With  a  solution  of  chloride  of  barium  it  gives  a  precipitate  inso* 
luble  in  hydrochloric  acid.  The  following  reactions  reach  their  limits 
when  one  part  of  anhydrous  sulphuric  acid  is  diluted  with  the  following 
quantities  of  water :  Keddening  of  litmus  paper,  immediate,  25,000 ;  in 
an  hour,  62,500 ;  precipitation  of  chloride  of  barium,  75,000 ;  of  chloride 
of  calcium,  310;  of  acetate  of  lead,  5,000  parts  of  water.  (Harting,  J,  pr. 
Chem.  22,  47.) 

Calculation.  Berxelius.       Richter.     Klaprotb.     Bacholz.      BerthoUet. 

S    ....  16  40  4014  4205  42*3  425  43762 

30  ....   24  60  59-86  57'95  57-7  57-5  56'238 

SO"       40  100  100-00  10000  1000  1000  100-000 

Vol.  Sp.gr.  Vol.  Sp.gr.  Vol.  Sp.  gf. 
Salpbnr  vapour  1  ....  6'6556  s  ^  ....  1*1093  Sulpburoiu  addgas  1  ....  2-2186 
Oxygen  gaa 9  ....  9*9837  »  1)  ....  1*6639        Oxygen  gas      }  ....  0*5546 

Sulphuric  add  yap.  6  ....16*6393  =  1  ....  2*7732        Sulphuric  add  vap.  1  ....  2*7732 
(S0>  «  201*17  +  3  .  100  =  501*17.    Berxeliu«.) 

Decompositions,  The  acid  when  passed  through  a  red-hot  porcelain 
tube  is  resolved  into  a  mixture  of  two  volumes  of  sulphurous  acid  gas  and 
one  volume  of  oxygen.  (Berzelius.) — 2.  Phosphorus  after  a  while  takes 
fire  in  the  vapour  of  anhydrous  sulphuric  acid  at  ordinaiy  temperatures, 
and  deposits  sulphur  in  the  form  of  a  thick  crust.  (F.  C.  Vogel.)— 
3.  Phosphuretted  hydrogen  gas  passed  over  the  anhydrous  acid  at  or- 
dinary temperatures  produces  a  copious  evolution  of  sulphnrons  acid,  and 
deposits  phosphoric  oxide.  (H.  Rose,  Pogg,  24, 140.)  It  generates  yellow 
fumes,  which  condense  in  the  form  of  a  yellow  powder;  and  on  the  fol- 
lowing day  a  blue  liquid  (sulphur  dissolved  in  anhydrous  sulphuric  acid) 
is  found  to  have  been  formed.  (Aim6,  J.  Pharm,  20,  87,  also  «/.  pr,  Chem. 
6,79.) — 4.  Mercury  when  heated  acts  rapidly  on  the  acid,  abstracting 
one  atom  of  its  oxygen,  and  forming  sulphate  of  mercuric  oxide,  with 
evolution  of  sulphurous  acid.  {Scheme  23.)  F,  C.  Vogel.  At  ordinary 
temperatures,  the  vapour  of  the  anhydrous  acid  does  not  act  upon  sinc^ 

VOL.    II.  N 


iJ8  SULPHUR. 

tin,  lead,  iron,  copper,  mercury,  or  silyer.  (Bi«io,  €fiom.  di  Fis.  8,  407 ; 
ako  Quart.  J.  of  Sc,  21, 176.)  ^  At  a  red  heat^  however,  iron  decomr 
poses  the  vapour  of  anhydrous  sulphuric  acid,  producing  a  fused,  blistered 
mass  having  a  greyish  metallic  aspect,  and  consisting  of  monosulphide  of 
iron  and  magnetic  oxide : 

4S0>  +  13  Fe  s  3  (Fc»  O*)  +  4PeS. 

Zinc,  under  similar  circumstances,  is  converted  into  a  mixture  of  oxide  and 
sulphide: 

80'  +  4Zn  =s  3ZnO  +  ZnS. 

(Albert  d'Heureuse,  Poffg.  75, 255-)  f 

Campaundi  of  Anhydrous  Sulphuric  acid  vnih  Sulphur,  P.  C.  Vogel 
has  discovered  that  anhydrous  sulphuric  acid  combines  with  sulphur 
in  several  proportions,  forming  a  brown,  a  &;reen,  and  a  beautiful 
blue  compound,  the  first  of  which  contains  the  ukrgest,  and  the  last  the 
smallest  quantity  of  sulphur.  The  green  compound  is  solid  at  ordinary 
temperatures;  the  other  two  are  liquid.  When  heated  they  evolve 
sulphurous  acid  and  sometimes  a  small  quantity  of  anhydrous  sulphuric 
acid,  while  oil  of  vitriol  remains  behind  (a  proof  that  water  was  previously 
contained  in  the  compound) — associated  with  sulphur,  in  the  case  of  the 
green  compound,  but  without  sulphur  in  that  of  the  blue.  In  contact 
with  water,  they  are  resolved,  with  great  development  of  heat,  into  sul* 
phuric  acid,  sulphurous  acid,  and  sulphur.  In  the  blue  compound, 
iihosphorus  takes  fire  instantly,  producing  a  deposition  of  sulphur.  The 
blue  compound  forms  sulphates  with  the  alkalis  and  earths,  the  combina- 
tion being  attended  with  evolution  of  sulphurous  acid  fi;as. 

Wach  prepared  these  compounds  by  placing  washed  and  well-dried 
flowers  of  sulphur  and  anhydrous  sulphuric  acid,  in  alternate  layers  in  a 
bent  glass  tube,  which  was  afterwards  sealed,  and  leaving  them  to  act 
upon  each  other  at  a  temperature  between  IG"*  and  19""  (60''— 66"^  F.). 
The  sulphur  was  first  converted,  with  slight  rise  of  temperature  and 
evolution  of  gas,  into  a  thick  red-brown  liquid,  which  subsequently,  by 
taking  up  more  acid,  assumed  a  brown,  green,  or  blue  colour. 

Brown  Compound,  Produced  by  the  action  of  8  pts.  (1  At.)  of  sul- 
phur on  10  pts.  (2  At.)  of  sulphuric  acid.  (When  from  9  to  10  parts  of 
sulphur  are  used  with  40  parts  of  acid,  a  portion  of  sulphur  remains  un- 
dissolved^ Clear,  brown  liquid,  not  solidifying  even  at  the  greatest 
degree  of  cold  that  could  be  produced.  When  exposed  to  daylight  at 
ordinary  temperatures,  it  deposits  needles  of  sulphur  in  the  course  of  24 
hours.  Begins  to  boil  in  the  sealed  tube  at  37*5  (99*5  F.),  and  separates 
into  a  brownish-yellow  and  a  brown  stratum,  the  latter  being  at  the 
bottom.  Sulphur  is  then  deposited,  and  liquid  sulphurous  acid,  containing 
at  most  0*4  per  cent,  of  anhydrous  sulphuric  acid,  collects  in  the  cold 
arm  of  the  tube.  This,  when  poured  oack  into  the  heated  arm,  does 
not  mix  with  the  other  liquid  on  agitation,  but  forms  a  colourless  stratum 
on  the  top  of  it. 

Green  Compound,  Formed  by  the  combination  of  6  pts.  sulphur  and 
40  pts.  anhydrous  acid.  (With  5  pts.  sulphur,  a  liquid  is  formed  which 
is  blue  by  reflected,  and  greenish  blue  by  transmitted  light.)  This  com- 
pound is  of  a  deep  green  colour,  and  perfectly  liquid,  even  in  the  cold 
(contrary  to  Vogel's  assertion).  Exposed  to  daylight  at  ordinary  tem- 
peratures, it  soon  turns  brown  and  deposits  sulphur  in  flakes.  Turns 
orown  almost  instantly  when  heated. 


SULPHURIC  ACID.  179 

Blue  Compound,  Fonned  by  the  union  of  4  pts.  (1  At.)  sulphur  and 
40  pt8.  (4  At.)  sulphuric  acid.  (1  to  3  parts  sulphur  and  40  of  acid 
produce  a  mixture  of  the  blue  compound  with  unaltered  acid.)  Indigo- 
blue,  transparent  liquid,  not  freezing  at — 22'5  (— S'd^'F.).  By  exposure 
to  daylight  it  gradually  becomes  of  a  paler  blue  colour ;  and  in  6  weeks, 
of  a  brownish-fellow,  a  few  flakes  of  sulphur  also  separating  from  it: 
in  direct  sunshine,  this  change  takes  place  in  8  hours.  If  the  arm  of  the 
tube  containing  the  compound  be  cautiously  heated  to  56°  (133°  F.)  while 
the  other  arm  is  cooled  to  —  10°  (+  14°  F.)  it  separates  into  a  lower  stra- 
tum of  a  brownish  colour,  and  an  upper  stratum  of  a  wine-yellow  tint,  and 
begins  to  boil — the  ebullition  then  continuing  auietly  even  at  31°  {SS""  F.), 
vith  precipitation  of  pale-yellow  sulphur,  till  the  upper  stratum  of  liquid 
has  entirely  disappeared,  and  passed  over  to  the  cold  arm  of  the  tube  in 
the  form  of  liquid  sulphurous  acid.  This  liquid  contains  about  5  per 
cent,  of  sulphuric  acid.  When  poured  back  upon  the  brown  residue  in 
the  other  arm,  it  does  not  mix  with  that  liquid  but  forms  a  colourless 
stratum  on  the  top  of  it.  The  brown  residue,  which  does  not  boil  even 
at  the  melting  point  of  sulphur,  presents  the  characters  of  oil  of  vitriol 
[consequently,  water  could  not  have  been  completely  excluded].  The 
transparent  and  therefore  partially  hydrated  acid  likewise  forms  the  blue 
compound  with  sulphur.     [Thus  iar  W ach.] 

When  the  vapour  of  anhydrous  sulphuric  acid  is  passed  into  a  tnb^ 
containing  sulphur — ^moisture  being  as  far  as  possible  excluded — and  the 
tube  seal^,  the  blue  compound  is  formed  at  particular  places  only,  and 
is  immediately  decomposed  again,  with  formation  of  a  thinly  fluid  com- 
pound of  anhydrous  sulphurous  and  sulphuric  acid.  But  if  a  trace  of 
moisture  be  present,  the  sulphur  forms — ^with  slight  evolution  of  gas — a 
liquid  which  is  first  brown,  then  green,  and  lastly  blue.  This  becomes 
paler,  and  is  converted,  in  the  course  of  a  day  or  two,  into  a  colourless 
mixture  of  the  two  acids.  On  opening  the  tube,  the  sulphurous  acid 
escapes  with  violence,  and  the  rest  of  the  sulphur  often  turns  blue  again 
by  combining  with  the  remaining  sulphuric  acid.  Oil  of  vitriol  dissolves 
sulphur  in  very  small  quantity  only,  and  very  slowly.  (Fischer,  Fogff. 
16,  119. 

When  ammoniacal  ^as  is  passed  over  the  blue  liquid,  violent  action 
takes  place,  the  liquid  assumes  a  carmine  colour,  and  is  ultimately 
converted  into  a  white  mass  of  ammoniacal  salts  with  reddish  spots  here 
and  there.  Water  dissolves  these  salts,  and  leaves  sulphur  behind.  (H. 
Rose,  Fogg,  32,  98.) 

Compound  of  Anhydrous  Sulphuric  add  witJi,  StUphurotu  acid.  In 
order  that  sulphurous  acid  may  be  abundantly  absorbed  by  sulphuric 
acid,  both  acids  must  be  as  nearly  anhydrous  as  possible.  The  sul- 
phurous acid  gas  is  passed  through  a  tube  four  feet  long  filled  with 
freshly  ignited  chloride  of  calcium,  into  a  bottle  olosed  with  a  cork  and 
cooled  to  zero,  containing  the  anhydrous  sulphuric  acid.  The  liquid 
compound  as  it  forms  is  poured  off  from  time  to  time  from  the  remaining 
sulphuric  acid.  This  compound  is  a  thin  liquid  (brownish  from  the  action 
of  the  sulphuric  acid  on  the  cork),  which  evaporates  rapidly  in  the  air, 
forming  an  exceedingly  thick  cloud,  with  the  odour  of  sulphurous  acid, 
and  sometimes  leaving  only  a  trace  of  oil  of  vitriol.  It  contains  from 
67-68  to  72-9  per  cent,  of  sulphurous  acid;  which  nearly  agrees  with  the 
formuk,  SO^  H-  2S0^. — ^When  kept  for  a  long  time  it  loses  part  of  its 
sulphurous  acid. — With  water  it  effervesces  violently,  evolving  sulphurous 
acid.     It  absorbs'dry  ammoniacal  gas,  forming  a  yellowish  body,  which 

N  2 


180  Sulphur. 

behaves  likd  ft  hiixiaye  of  anhydrous  sulphate  of  ammon^  and  anhy- 
drous sulphite  of  ammon.  (H.  Rose^  Pogg.  39,  173.) 

OUur  Compoundi  of  Sulphuric  acid,  a.  With  Water.  Sulphuric  acid 
has  a  peculiarly  strong  affinity  for  water :  its  combination  with  the  first 
atom  of  that  substance  is  attended  with  great  development  of  heat.  When 
4  parts  of  anhydrous  sulphuric  acid  are  mixed  with  1  part  of  water,  the 
resulting  compound  is  converted  into  vapour,  with  explosion  and  emission 
of  light.  (F.  C.  Vogel.)  The  acid  when  exposed  to  the  air,  produces 
white  fumes,  because  its  vapour  combines  with  the  aqueous  vapour  in  the 
air,  and  forms  oil  of  vitriol. 

a.  In  the  distillation  of  fuming  oil  of  vitriol  (  Vid,  p.  176%  a  compound 
of  a  very  large  quantity  of  sulphuric  acid  with  a  very  small  quantity  of 
water,  passes  over  after  the  anhydrous  acid,  and  solidifies  in  large  trans- 
parent tabular  crystals. 

p.  f^ordhausen,  German,  Fuming,  Brown  Oil  of  Vitriol,  This  liquid 
is  prepared  by  lon^  continued  ignition  of  green  vitriol  previously  freed 
from  its  water  of  crystallization,  and  converted  into  sulphate  of  ferric  oxide 
by  heating  it  in  the  air :  the  material  is  placed  in  earthen  retorts  heated 
in  a  reverberatory  furnace.  The  earthen  receivers  are  kept  cool,  and  if 
the  calcined  green  vitriol  is  quite  dry,  a  little  water,  or  common  oil  of 
vitriol,  according  to  more  recent  practice,  is  put  into  them ;  otherwise  the 
vapours  of  anhydrous  sulphuric  acid  which  pass  over  would  not  be  pro- 
perly condensed.  The  samo  liquid  may  likewise  be  formed  by  mixing 
anhydrous  sulphuric  acid  with  common  oil  of  vitriol.  Properties,  Light 
brown  (in  consequence  of  a  little  organic  matter),  viscid  like  oil ;  of  spe- 
cific gravity  1-896,  according  to  Thomson;  of  Q^"" — 68®  B.  according  to 
Bussy.  Solidifies  a  little  ^)ove  0^,  diminishing  in  bulk,  and  forming 
colourless,  transparent  crystals.  Fumes  in  the  air;  boils  between  40"^  and 
50^  (Bussy),  and  is  thereby  resolved  into  anhydrous  acid,  which  passes  off 
in  vapour,  and  sometimes  amounts  to  25  per  cent.,  and  common  oil  of 
vitriol  which  remains  behind.  (The  boiling  point  rises  as  the  quantity  of 
anhydrous  acid  diminishes.)  By  mixing  it  with  a  small  quantity  of  water, 
whereby  great  heat  is  evolved,  it  is  converted  into  common  oil  of  vitriol. 
It  must  therefore  be  regarded  as  a  compound  of  one  atom  of  water  with 
several  atoms  of  anhydrous  sulphuric  acid,  or  of  ordinary  oil  of  vitriol 
with  anhydrous  acid.  It  is  often  contaminated  with  sulphurous  acid,  sele- 
nium, earthy  matters,  oxide  of  iron,  and  organic  matter.  When  common 
English  oil  of  vitriol  has  been  put  into  the  receivers,  it  contains  the  same 
impurities  as  that  li(|[uid  itself. 

y.  Sulphuric  acid  wiih  one  atom  of  Water.  Common  Oil  of  Vitriol^ 
Concentrated  Sulphuric  acid.  This  is  the  most  intimate  compound 
of  sulphuric  acid  and  water.  It  is  left  behind  when  fuming  oil  of 
vitriol  is  heated  till  all  excess  of  acid  is  driven  off,  and  likewise  when 
dilute  sulphuric  acid  is  boiled  till  the  residue  no  longer  increases  in 
density. 

It  is  prepared  on  the  large  scale,  aa  English  or  White  Oil  of  Vitriol, 
by  burning  sulphur  mixed  with  \  of  its  weight  of  nitre  in  a  spacioua 
chamber,  called  the  Leaden  Chamber,  constructed  principally  of  lead 
plates,  filled  with  air  and  aqueous  vapour,  and  having  its  floor  covered 
with  water.  Sometimes  also  the  sulphur  is  burned  by  itself,  vessels  con- 
taining nitric  acid  being  placed  in  the  leaden  chamber,  or  vapours  of  nitric 
or  hyponitric  acid  being  passed  into  it.  The  nitrons  gas  evolved  from 
the  nitre  or  nitric  acid  takes  oxygen  from  the  air,  and  transfers  a  portion 


SULPHURIC  ACID.  181 

of  it  to  the  Gulpharous  acid  produced  by  the  combustion  of  the  sulphur. 
(Vid.  p.  176,  also  Nitrogen  and  Sulphur.)  The  water  impregnated  with 
sulphuric  acid  (SauerwdsserY  which  has  a  specific  gravity  of  about  1-2  or 
I'd,  is  first  concentrated  in  leaden  vessels  to  the  density  of  at  most  1*78^ 
and  afterwards  distilled  in  vessels  of  glass  or  platinum,  till  the  less  inti- 
mately combined  water,  together  with  the  nitric  and  hydrochloric  acids, 
has  passed  off,  and  the  oil  of  vitriol  begins  to  evaporate  in  white  fumes. 
In  general,  however,  the  distillation  is  not  carried  quite  so  far,  so  that 
common  English  oil  of  vitriol  is  really  a  mixture  of  HO,  SO'  and  2H0,S0'. 
Iron  pyrites  or  copper  pyrites  is  sometimes  burnt  instead  of  sulphur;— or 
sulphate  of  lime  is  i^ited  with  charcoal ;  the  sulphide  of  calcium  thereby 
produced  diffused  through  water;  carbonic  acid  gas,  generated  by  the 
following  ignition  of  sulphate  of  lime,  passed  through  the  liquid ;  and  the 
sulphuretted  hydrogen  thereby  evolved  from  the  sulphide  of  calcium  burnt 
in  the  leaden  chamber.  (Thaulow,  N,  Br.  Arch,  26,  165.)  Instead  of 
Inducing  the  transfer  of  atmospheric  oxygen  to  the  sulphurous  acid  through 
the  medium  of  nitric  oxide,  the  sulphurous  acid  generated  by  the  com- 
bustion of  the  sulphur  may  be  passed,  mixed  with  air,  through  a  strongly 
ignited  porcelain  or  platinum  tube  filled  with  platinum  wire  or  spongy 
platinum  (p.  176;  Per.  Phillips,  Fogg.  24,  610).  On  the  small  scale,  the 
aspirator  may  be  used  for  this  purpose.  (Brunner.) 

Common  oil  of  vitriol  may  contain  the  following  impurities :  Excess  of 
water  (by  which  it  is  rendered  specifically  lighter,  and  crystallizable  by  a 
moderate  degree  of  cold);  hydrochloric  acid  (from  impurities  in  the  nitre); 
nitric  oxide,  nitrous  and  nitric  acids ;  potassa  (from  the  nitre,  first  observed 
by  Qottling,  Taschenb,  1782,  119);  oxide  of  lead  (derived  from  the  leaden 
vessels, — separates  on  diluting  with  water,  as  a  white  precipitate  of  sulphate 
of  lead) ;  and  lastly,  from  accidental  impurities  in  the  sulphur  or  pyrites 
consumed;  selenium;  lime;  magnesia;  titanium  (Pfaff,  Sc/iw,  18,  283); 
arsenic ;  oxide  of  zinc;  and  binoxide  of  tin  (Berzelius,  Schw,  23, 313 ;  Pogg. 
33,  24) ;  sesqui-oxide  of  iron  (forming  a  white  deposit  of  ferric  sulphate, 
which  disappears  on  diluting  the  acid  with  water) ;  oxide  of  copper  (Ber- 
zelius and  Trommsdorff,  N,  Tr.  3,  2,  64  and  4,  1,  130);  and  mercury 
(Berzelius,  Schw,  23,  313).  Many  of  these  substances  are  not  dissolved 
by  the  oil  of  vitriol,  but  merely  form  a  sediment  in  it.  (  Vid,  Giese,  Scher. 
Ann,  6,  1.)  Organic  matter  accidentally  introduced  mto  oil  of  vitriol 
imparts  to  it  a  brown  colour  which  disappears  on  boiling. 

Hydrochloric  acid.  Mullen  {QuaH.  J,  of  Sc,  22,  231  and  N,  QuaH.  J. 
ofSc,  2,  258)  and  Johnston  {M.  Quart.  J.  ofSc,  3, 154)  found  that  peroxide 
of  manganese  or  red  lead,  free  from  chlorine,  evolved  chlorine  gas  when 
treated  with  sulphuric  acid.  Kane  {N,  Quart,  J.  of  Sc.  4,  286)  pointed 
out  that  oil  of  vitriol  contains  from  0*03  to  0*14  per  cent,  of  hydrochloric 
acid,  whence  the  preceding  observation  is  easily  explained.  (See  the 
supposed  formation  of  peroxide  of  hydrogen  by  the  mutual  action  of  sul- 
phuric acid  and  metallic  peroxides,  p.  74.) 

The  presence  of  nitric  oxide,  nitrous  acid,  or  nitric  acid  in  oil  of 
vitriol,  is  best  detected  by  the  addition  of  a  solution  of  sulphate  of  ferrous 
oxide,  which  produces  a  purple  colour,  even  if  the  nitrogen-compound 
amount  to  no  more  than  f^,^^^  of  the  whole.  (Desbassins,  J.  Chitn.  Med, 
H)  508.)  A  tolerably  strong  solution  of  the  ferrous  sulphate  is  to  be  cau- 
tiously poured  upon  the  surface  of  the  oil  of  vitriol,  so  as  to  form  a  layer 
one-fourth  as  deep  as  the  oil  of  vitriol  itself.  The  red  colour  appears  at 
the  common  surface  of  the  two  liouids :  if  it  should  disappear  after  a  time,  it 
jjfiay  be  restored  by  agitation.  ( Wackenroder^ilnrt.  Phaim.  18, 152.)    An- 


182  SULPHUR. 

other  mode  of  making  the  experiment  is  to  ponr  carefully  half  a  gramme 
of  water  on  the  surface  of  50  grammes  of  oil  of  yitriol — ^wait  till  the  heat 
thereby  developed,  which  woold  destroy  the  colour,  has  been  dissipated — 
and  then  add  10  drops  of  the  iron  solution,  mixing  slowly,  so  that  the  liquid 
may  not  become  heated.  In  this  manner,  1  part  of  nitric  acid,  nitrons 
acid,  or  a  nitrate,  mixed  with  1429  parts  of  oil  of  yitriol,  maybe  made  to 
give  a  bright  red ;  with  142,900,  a  pale  red;  and  with  333,333,  a  pale  rose* 
colour;  while  with  500,000  parts  of  oil  of  vitriol  (the  limit)  the  colouring 
is  just  perceptible.  (Jacauelain,  Compt.  Rend.  14,  643.) 

Every  sample  of  English  oil  of  vitriol  examined  by  E.  Baruel  {J,  Ckim. 
Med,  12,  180;  also  ilnn.  Pharm,  22,  286)  exhibited  the  reaction  just 
described,  but  in  very  different  degrees.  Oil  of  vitriol  thus  contaminated 
dissolves  platinum  at  a  boiling  heat ;  yields,  when  distilled  with  common 
salt,  hydrochloric  acid  mixed  with  free  chlorine ;  and  forms  with  indigo, 
not  a  pure  blue,  but  a  greenish  blue  solution.  ^E.  Baruel.) — The  nitrogen 
compound  present  is  nitrous  acid ;  for  nitric  acid  mixed  with  oil  of  vitriol 
passes  off  at  the  beginning  when  the  liquid  is  distilled,  whereas  the  azotised 
compound  actually  present  in  the  oil  of  vitriol  is  intimately  combined  with  it. 
Oil  of  vitriol  of  this  description  likewise  decolorizes  sulphate  of  manganic 
oxide,  instantly  precipitates  sulphur  from  hydrosulphuric  acid  water,  and 
when  diluted  with  2  parts  of  water,  evolves  the  odour  of  nitrous  acid. 
(Wackenroder,  Ann,  Pharm.  18,  152.) — The  azotised  compound  usually 
occurring  in  common  oil  of  vitriol  is  not  nitric  or  nitrous  acid,  but  nitric 
oxide.  When  oil  of  vitriol  of  this  kind  is  distilled,  the  first  \  of  the  liquid 
pass  over  free  from  nitric  oxide,  and  consequently  do  not  redden  a  solution 
of  green  vitriol.  The  following  portions  of  the  distillate  contain  more  and 
more  nitric  oxide;  and  the  residue  is  so  rich  in  that  compound,  that  when 
diluted  with  water,  it  evolves  nitric  oxide  gas  in  abundance,  and  if  contact 
of  air  be  prevented,  the  gas  so  evolved  is  colourless.  If  oil  of  vitriol  con- 
taining nitric  oxide  be  diluted  with  water  till  its  density  is  reduced  to  1  % 
it  gives  up  all  its  nitric  oxide  when  concentrated  to  the  strength  of  oil  of 
yitriol.  From  this  it  would  appear  that  the  dilute  acid  of  the  leaden  cham- 
bers must  give  up  all  its  nitric  oxide  during  the  process  of  concentration ; 
but  on  the  one  hand,  it  is  admitted  continuously  into  the  platinum  retorts 
which  already  contain  a  more  concentrated  acid ;  and  on  the  other  hand, 
nitric  acid  is  often  mixed  with  the  oil  of  vitriol  at  a  subsequent  stage  of 
the  process,  in  order  to  destroy  the  organic  matter  which  colours  it  brown. 
(A.  Rose,  Po^^.  50,  161.) 

Nitric  acid  in  oil  of  yitriol  may  be  distinguished  from  nitrous  acid  and 
nitric  oxide  by  the  following  characters :  If  oil  of  vitriol  which  contains 
it  be  mixed  with  water  and  hydrochloric  acid,  it  will  dissolve  gold  leaf  on 
boiling;  when  diluted  with  water  and  boiled  with  solution  of  indigo,  it 
destroys  the  colour.  (Jacquelain.)  When  it  is  subjected  to  distillation^ 
the  nitric  acid  passes  over  with  the  first  portions;  afterwards  pure  oil  of 
vitriol  is  obtained,  and  finally  an  acid  which  may  contain  nitrous  acid  (or 
nitric  oxide)  in  solution.  (Wackenroder ;  A.  Rose.) 

To  purify  oil  of  vitriol  from  the  oxides  of  nitrogen,  E.  Baruel  heats 
21  parts  of  it  with  1  part  of  sulphur,  at  a  temperature  between  150^  and 
200^  for  several  hours,  till  the  liquid,  which  gradually  acquires  a  brown 
colour,  evolves  the  odour  of  sulphurous  acid.  To  expel  ttie  sulphurous 
acid  thus  produced,  Jacquelain  mixes  the  oil  of  vitriol  with  chlorine  water, 
and  boils  for  a  few  minutes  till  the  hydrochloric  acid  is  driven  off. 
Wackenroder  heats  the  oil  of  vitriol  witn  paper,  or  better,  with  sugar, 
till  the  liquid,  which  at  first  turns  blacky  begins  to  boil  and  again  becomes 


SULPHURIC  ACID.  183 

oolonrless :  the  addition  of  a  little  faming  oil  of  yitriol  hastens  the  decolo* 
rization.  Pelouze  (Ann.  Chim,  Phys,  71,  52)  heats  the  oil  of  vitriol  to 
1 60®  ^320°  F.),  with  from  ^V  *^  i  V^^  <^^'-  ^^  sulphate  of  ammonia  (the 
quantity  being  determined  by  previous  trials) ;  the  ammonia  and  nitrio 
oxide  or  nitric  acid  are  then  resolved  into  water  and  nitrogen  gas.  The 
ammoniacal  salt  may  be  added  immediately  to  the  dilute  acid  which 
is  to  be  evaporated  in  the  leaden  pans ;  and  thus  the  corrosion  of  the  pla< 
tinum  retort  will  be  avoided.  A.  Rose  heats  the  oil  of  vitriol  diluted  with 
twice  its  weight  of  water  in  a  retort  till  sulphuric  acid  begins  to  distil 
over. 

Arsenic,  which  has  been  often  detected — and  frequently  in  consi- 
derable quantity — in  oil  of  vitriol,  by  Martins,  {Schw.  3,  363),  Wacken- 
roder  {Hepert,  47,  337),  A.  Vogel  {J.  pr,  Chem.  4,  232),  Dulk  (^Berl. 
Jahrb.  34,  1,  247),  Ficinus  (Ann.  Fharm.  15,  78),  and  Arthaud  (J. 
Chim,  Med.  16,  620),  appears  to  exist  in  it,  for  the  most  part,  in  the 
state  of  arsenious  acid.  Very  small  quantities  of  it  may  be  detected  by 
diluting  the  oil  of  vitriol  with  water,  supersaturating  with  carbonate  o| 
potassa,  filtering  from  the  precipitated  sulphate  of  potassa,  washing  with 
a  small  quantity  of  water,  evaporating,  supersaturating  with  hydrochloric 
acid,  and  passmg  hydrosulphuric  acid  gas  through  the  liqnicT.  (Dulk.) 
Arsenical  oil  of  vitriol  diluted  with  water,  gives  with  hydrosulphurio 
acid,  a  precipitate  of  sulphide  of  arsenic  and  sulphide  of  lead,  often 
amounting  to  more  than  one  per  cent.,  and  deposits  after  a  while^  a  little 
more  sulphide  of  arsenic :  the  greater  part  of  the  arsenic  ap^ars  there- 
fore to  exist  in  the  form  of  arsenious  acid,  but  a  small  quantity  likewise 
in  the  form  of  arsenic  acid.  This  supposition  is  corroborated  by  the} 
reddish  tint  ultimately  assumed  by  the  precipitate,  which  the  arsenical 
oil  of  vitriol  neutralized  with  ammonia  gives  with  nitrate  of  silver. 
(Wackenroder.)  A.  Vogel  found  nothing  but  arsenious  acid.  Accord- 
ing to  his  observations,  three-fourths  of  the  oil  of  vitriol  may  be  dis- 
tilled overj  free  from  arsenic.  According  to  Wackenroder,  the  distillate 
contains  arsenic,  and  therefore  the  oil  of  vitriol — in  order  to  purify  it 
from  arsenic  and  lead — ^must  be  diluted  with  water,  saturated  with 
hydrosulphuric  acid,  left  to  stand  for  several  days  in  a  close  vessel^ 
decanted  from  the  precipitated  sulphides,  and  exposed  to  the  air,  that  the 
excess  of  hydrosulphuric  acid  may  escape.  According  to  Ficinus,  also, 
arsenic  passes  over  with  the  distillate;  he  therefore  recommends  that 
hydrated  ferric  oxide  be  added  to  the  oil  of  vitriol,  and  the  distillation 
stopped  when  two-thirds  of  the  liquid  have  passed  over.  The  residue 
in  the  retort  poured  off  from  the  white  sediment,  is  likewise  free  from 
arsenic. 

When  oil  of  vitriol  is  evaporated  in  a  platinum  dish,  the  less  volatile 
impurities  remain  behind. 

Rectified,  Distilled,  or  Purified  OH  of  Vitriol  is  obtained  by  distilling 
either  the  fuming  or  the  English  oil  of  vitriol  in  glass  retorts  or  plati- 
num stills.  Fuming  oil  of  vitriol  is  the  best  for  this  purpose ;  for  aftex 
the  anhydrous  acid,  and  the  almost  anhydrous  acid  with  the  selenium 
have  passed  over,  pure  oil  of  vitriol  is  obtained  on  changing  the  receiver. 
When  English  oil  of  vitriol  is  used,  it  is  often  necessary,  bdfore  distilling, 
to  remove  the  nitric  oxide  and  the  arsenic  by  the  preceding  methods. 
When  the  excess  of  water  with  which  the  hydrochloric  acid,  nitric  acid, 
Sec,  may  be  associated,  has  passed  off,  the  oil  of  vitriol  may  be  collected 
in  a  fresh  receiver.  In  consequence  of  the  high  temperature  required 
for  the  distillation,  the  neck  of  the  retort,  and  the  receiver  are  very  apt 


184  SULPHUB. 

to  break.  The  qaantity  of  oil  of  yitriol  distilled  in  one  operation  should 
not  exceed  4  pounds.  The  retort  is  either  immersed  in  a  sand-bath  which 
can  be  completely  surrounded  with  fire,  or  else  it  is  exposed  to  an  open 
charcoal  or  coke  fire,  but  sunk  deep  in  the  furnace,  so  that  the  heat  may 
be  applied  not  only  to  the  bottom  but  all  round  it.  The  heat  is  main- 
tained uniformly  at  such  a  degree  as  to  keep  the  liquid  in  continuous 
gentle  ebullition.  The  neck  of  the  retort  is  either  made  to  reach  to 
the  middle  of  the  receiyer,  so  that  the  heated  drops  which  fall  from  it 
may  mix  at  once  with  the  liquid  already  eone  over;  or,  if  it  does  not 
pass  beyond  tbo  neck  of  the  receiver,  a  long  strip  of  platinum  foil  is 
adjusted  within  the  receiver  in  such  a  manner,  that  the  acid,  as  it  drops 
from  the  mouth  of  the  retort,  may  run  down  the  metal  into  the  body  of 
the  receiver.  Closing  the  ioint  with  paper,  luting,  &c.,  is  superfluous,  and 
may  do  harm.  The  distillation  must  not  be  carried  to  dryness,  but  only 
till  three-fourths  of  the  liquid  has  passed  over.  As  the  quantity  of  acid 
in  the  retort  diminishes,  the  sulphate  of  lead  dissolved  m  the  common 
oil  of  vitriol  separates  from  the  liquid,  and  causes  a  dangerous  percussive 
ebullition.  (I.,  276.)  The  acid  remains  tranauil  for  awhile,  and  then, 
when  a  certain  amount  of  heat  has  accumulated  in  it,  so  great  a  quantity 
of  vapour  is  suddenly  evolved,  that  not  only  is  the  acid  projected  with 
violence  into  the  receiver,  and  the  receiver  broken  by  tne  heat  of  the 
liquid  suddenly  brought  in  contact  with  it,  but  sometimes  the  elastic 
force  of  the  vapour  is  sufficient  to  burst  the  upper  part  of  the  retort,  and 
scatter  the  acid  all  about.  Platinum  wire  or  small  cuttings  of  platinum 
foil  counteract  this  percussive  ebullition  to  a  certain  extent,  as  Gay- 
Lussac  has  shown.  But  according  to  Berzelius  {Lehrh,  2,  16),  their 
efficacy  ceases  after  awhile ;  he  therefore  recommends  that  the  heat  be 
applied  only  to  the  sides  of  the  retort,  and  not  at  all  to  the  bottom. 

Properties  of  the  Mono-hydraUd  Sulphuric  add.  Colourless,  trans- 
parent, oily  liquid,  of  specific  gravity  1*848;  freezes  at  —25**  (H.  Davy), 
at  —  SS""  in  thermometer  bulbs  (Thomson);  boils  at  288**  (H.  Davy),  at 
327®  (Dalton),  passing  oflf  unaltered,  in  colourless  vapours,  which  pro- 
duce a  thick  white  cloud  in  contact  with  the  air.  Does  not  evaporate 
in  the  air  at  ordinary  temperatures.  (Bellani.)  Inodorous;  does  not 
fume.  Corrodes  organic  substances  very  strongly,  and  is  coloured  brown 
by  them. 

Calculatioii.  H.  Davy,  Dalton.  Klaproth.    Beithollet. 

S0»     40  81-63  81  74-4  72-675 

HO     9  18.37  19  25-6  27-325 

HO,  SO*  49  100-00  100  1000  lOO'OOO 

JDeeompodtions.  1.  When  common  oil  of  vitriol  of  sp.  gr.  1-8435  is 
kept  in  a  retort  for  several  days,  at  a  temperature  not  quite  up  to  its 
boilinff  point,  a  more  dilute  acid  passes  over  first,  exhibiting  on  the 
second  day  a  density  of  1-43;  then,  on  the  third  day,  a  fuming  acid 
which  crystallizes  on  cooling,  distils  over  (p.  180,  a);  and  the  residue, 
which  has  a  density  of  1-85,  likewise  fumes.  (C.  G.  Gmelin,  Fogg.  2, 
419.)  A  similar  observation  was  likewise  made  by  Julin,  (N,  Tr,  3,  2, 
538),  and  by  Hess  {Pogg.  24,  652),  in  whose  experiment,  after  6|  lb.  of 
acid  out  of  lOlb.  had  gone  over,  an  acid  containing  13*73  per  cent  of 
water,  crystallized  in  the  neck  of  the  retort.  (Can  it  be  that,  at  a  certain 
temperature,  4H0,S0»  is  resolved  into  2 HO,  SO*  and  2HO,3SO'?)— 
2.  Vapour  of  oil  of  vitriol  passed  through  a  porcelain  tube  heated  nearly 
to  whiteness^  is  partially  decomposed  into  2  volumes  of  sulphurous  acid 


SULPHURIC  ACID*  185 

gas  and  1  volume  of  oxygen.  (Gay-Lussao.)  — •  8.  By  the  electric 
current  it  is  resolved  into  oxygen  at  the  positive,  sulphur  and  hydrogen 
at  the  negative,  pole  (L,  452). — 4.  Vapour  of  oil  of  vitriol  and  hydro- 
gen gas  passed  together  through  a  red-hot  tohe,  form  water,  and  either 
sulphurous,  sulphuric,  or  hydrosulphuric  acid,  according  to  the  propor- 
tion of  hydrogen  present.  (Fourcroy  k  Thenard.) — 5.  Charcoal  decom< 
poses  oil  of  vitriol  with  the  aid  of  heat.  At  temperatures  between  100^ 
and  150^,  the  products  of  the  decomposition  are  carbonic  and  sulphurous 
acid;  at  a  red  neat,  carbonic  oxide,  carbonic  acid,  hydrogen,  and  sulphur. 
—6.  Phosphorus  heated  with  oil  of  vitriol  to  the  boiling  point  in  a  capa- 
cious flask,  takes  fire  in  the  acid  vapour  and  separates  the  sulphur. 
Phosphoric  oxide,  according  to  Pelouze,  does  not  act  on  oil  of  vitriol  in 
the  cold,  but  on  the  application  of  heat,  phosphoric  and  sulphurous  acids 
are  produced.  Phosphuretted  hydrogen  gas  slowly  decomposes  oil  of 
vitriol  at  ordinary  temperatures,  producing  phosphoric  acid,  sulphurous 
acid,  and  sulphur.  (H.  Rose,  Fogg,  24,  139.)  When  sulphur  and  oil  of 
vitriol  are  distilled  together,  sulphurous  acid  passes  over,  accompanied 
by  sulphuric  acid,  which  is  rendered  turbid  by  the  presence  of  sulphur. 
(F.  C,  Vogel.)  [For  the  decomposition  by  hydrosulphuric  acid,  see  that 
compound.] — 8.  Potassium  and  sodium  at  ordinary  temperatures  separate 
nothing  but  hydrogen  from  oil  of  vitriol.  Iron  and  zinc  evolve  only 
hydrogen  at  first;  but  afterwards,  when  the  temperature  rises,  they 
liberate  nothing  but  sulphurous  acid  gas.  Arsenic,  tellurium,  antimony^ 
bismuth,  tin,  lead,  copper,  mercury,  silver,  and  several  other  metals,  exert 
no  action  upon  oil  of  vitriol  in  the  cold ;  but  on  the  application  of  heat, 
they  cause  an  evolution  of  pure  sulphurous  acid  gas.  In  all  these  cases, 
a  metallic  sulphate  is  produced,  the  undecomposed  portion  of  the  acid 
combining  with  the  salifiable  base  formed  by  the  union  of  the  metal  with 
oxygen  derived  from  the  water  or  from  a  portion  of  the  sulphuric  acid. 
(Sch,  17  and  23.)  If  zinc  be  dissolved  in  dilute  sulphuric  acid,  and, 
when  the  temperature  of  the  liquid  has  risen  to  about  90°,  oil  of  vitriol 
be  poured  in,  so  that  it  may  lie  at  the  bottom  of  the  vessel  in  contact 
with  the  zinc,  hydrosulphuric  acid  will  be  evolved:  for  at  the  high 
temperature  which  the  liquid  has  attained,  oil  of  vitriol  and  zinc  produce 
sulphurous  acid ;  and  this,  by  the  action  of  the  zinc,  is  further  converted 
into  hydrosulphuric  acid,  (p.  171.  Fordos  &  Gelis,  J.  Pharm.  27,  730.) 
Some  metals,  as  tungsten,  gold,  platinum,  rhodium,  and  iridium,  do  not  act 
on  sulphuric  acid  at  any  temperature. — 9.  When  oil  of  vitriol  is  heated  in 
contact  with  a  fixed  base,  such  as  lime,  an  anhydrous  sulphate  remains, 
while  the  water  of  the  oil  of  vitriol  escapes. 

Jl  Birhydrated  Svlphuric  add.  2H0,  SO'.  Sometimes  called  Glacial 
Oil  (Eisbl).  The  liquid  formed  by  the  union  of  1  atom  of  sulphuric  acid 
and  2  atoms  of  wat«r,  and  therefore  containing  31  water  and  69  acid 
in  100  parts,  has  a  density  of  1*780,  solidifies  at  9°  (48*2''  FX  according  to 
Chaptal,  and  above  7'5  (45*5*'  F.),  according  to  Dalton,  in  colourless,  trans- 
parent, six-sided  prisms,  terminated  by  six-sided  summits.  Between  205** 
and  210^,  this  compound  loses  its  second  atom  of  water — a  portion  of 
sulphuric  acid,  however,  evaporating  at  the  same  time — and  leaves  oil 
of  vitriol.  ^Graham.)  Graham  regards  one  atom  of  water  as  basic, — the 
other,  whicn  is  less  intimately  combined,  as  constitutional,  HO,  SO'-hHO. 

t.  Ter-hydraUd  Sulphuric  acid.  3H0,S0^  According  to  Ure,  the 
combination  of  40  pts.  (1  At.)  of  anhydrous  sulphuric  acid  with  27  pts. 
(3  At.)  of  water  (in  which  proportions  the  acid  and  water  contain  eaual 
quantities  of  oxygen)  is  attended  with  the  maximum  degree  of  conaen- 


186 


SULPHUR. 


sation.  If  49  pts.  oil  of  ylfcriol  and  18  water  occapj  before  mixtnre  the 
space  of  100  measures^  they  will,  after  mixture,  fill  up  only  92*14 
measures.  (Ure.)  The  specific  gravity  of  this  mixture  is  1  '632 1 .  Between 
193°  and  199°  it  loses  1  atom  of  water,  which  passes  off  unaccompanied 
by  acid,  the  residue  haying  exactly  the  composition  2H0,  SO'.  (Graham.) 
This  hydrate  boils  between  163°  and  170°.  (Liebig.) 

{  ViliUe  Sulphuric  acid.  Called  Spirit  oj  Vitriol,  when  in  the  pro- 
portion of  1  part  acid  and  from  3  to  5  water.  Sulphuric  acid  may  be 
diluted  with  water  in  any  proportion  whatever.  According  to  Gay- 
Lussac,  oil  of  vitriol  placed  in  an  atmosphere  saturated  with  moisture 
absorbs  15  times  its  weight  of  water. 

The  combination  of  oil  of  vitriol  with  water  is  attended  with  ^reai 
development  of  heat;  but  that  of  oil  of  vitriol — and  still  more  of  ^  and  r— • 
with  snow,  produces  intense  cold.  When  oil  of  vitriol  is  poured  into 
water  in  successive  portions  rapidly  following  one  another,  and  without 
stirrinff,  phosphorescence  is  sometimes  produced,  and  lasts  for  some  seconds. 
(Gobe^  Schw,  58,  488.)  On  mixing  4  parts  of  oil  of  vitriol  with  1  part 
of  water,  the  temperature  rises  from  0°  to  100^  (Berzelius;  comp.  Hess, 
I.,  294.)  One  part  of  oil  of  vitriol  with  1  part  of  snow  evolves  heat; 
with  f  of  snow,  no  change  of  temperature  occurs;  and  with  a  larger 
quantity,  intense  cold  is  produced.  (Richter.)  Bi-hydrated  and  ter- 
hydrated  sulphuric  acid  dissolve  snow  with  production  of  intense  cold 
(L,  299).  Sulphuric  acid  loses,  by  dilution,  its  corrosive  action  on  organic 
substances.  Dilute  sulphuric  acid,  when  heated,  parts  with  its  water,  till 
it  is  brought  to  the  strength  of  ordinary  oil  of  vitriol ;  and  this,  on  being 
further  heated,  evaporates  unchanged.  The  compound  of  1  atom  of 
anhydrous  sulphuric  acid  with  4  At.  water  boils  between  136°  and  141°; 
and  that  of  1  At.  sulphuric  acid  with  5  At.  water,  between  118°  and  122°. 
(Liebig,  Fogg,  31,  352.)  When  dilute  sulphuric  is  kept  for  40  hours  in 
vacuo  at  100°,  there  remains  a  compound  of  40  pts.  (1  At.)  of  acid  with 
27*228  (or  rather  more  than  3  At.)  water.  When  the  dilute  acid  is 
boiled,  pure  water  is  given  off  at  first,  no  acid  vapour  mixing  with  the 
vapour  of  water  till  the  liquid  is  brought  to  the  proportion  of  2  At.  water 
and  1  At.  acid.  (Graham.) 

QtuzfUity  qf  Oil  of  Vitriol  in  Aqueotu  Sulphuric  Acid. 


Vauquclin  {Ann,  Chim 

.  76,  260). 

OU  of  Vitriol, 
per  cent. 

Darcet 

{Ann.  Chim.  Phyn.  1,  198). 

Baume's 
Areometer. 

Spec.  Gray. 

Baume's 
Areometer. 

1 

1  Spec.  Grav. 

Oa  of  Vitriol, 
per  cent. 

66^ 

1-842 

100 

66** 

;         1-844 

100 

60 

1-725 

84-22 

60 

'        1-717 

82-34 

65 

1-618 

74-32 

55 

I        1-618 

74-32 

50 

1-524 

66-45 

54 

1-603 

72-70 

45 

1-466 

58-02 

53 

1-586 

7117 

40 

1-375 

50-41 

52 

1-566 

69-30 

35 

1-315 

43-21 

51 

1-550 

6803 

30 

1-260 

36-52 

50 

1-532 

66-45 

25 

1-210 

3012 

49 

1         1-515 

64-37 

20 

1162 

24-01 

48 

1         1-500 

62*80 

15 

1-114 

17-39 

47 

1-482 

61-32 

10 

1-076 

11-73 

46 

1-466 

59-85 

5 

1-023 

6-60 

45 

1         1-454 

58-02 

SULPHURIC  ACID. 


187- 


QuantUiet  of  Anhydrous  Acid  and  Oil  of  Vitriol  inAqueotu  StUphurio 

Acid, 


Anhydrous  Acid 
Dalton  (N.  Syst.  2, 

210). 

Anhydrous  Acid  and  Oil  of  Vitriol. 
Ure  {Schw.  35,  444). 

Percentage. 

Percentage. 

Percent! 

Spedflo    Anhydrous 
Gratity.       Add. 

«e. 

Specific    > 
Gnrity. 

knbydroof  BoiUng 
Aeid.     1  Point 

1-8485 

kDhydrovM  OU  of 
Acid.       Titriol. 

Oil  of 
Vitriol. 

1-850 

81       ' 

326** 

81-54 

100 

1-3884 

40.77 

50 

1-849 

80 

318 

1-8460 

79-90 

98 

1-3697 

39-14 

48 

1-848 

79 

310 

1-8410 

78-28 

96 

1-3530 

37-51   1 

46 

1-847 

78 

301 

1-8336 

76-65 

94 

1-3345 

35-88   1 

44 

1-845 

77 

293 

1-8233 

7502 

92 

1-3165 

34-25    1 

42 

1-842 

76 

285 

1-8115 

73-39 

90 

1-2999 

32-61 

40 

1-838 

75 

277 

1-7962 

71-75 

88 

1-2826 

30-98 

38 

1-833 

74 

268 

1-7774 

70-12 

86 

1-2654 

29-35 

36 

1-827 

73 

260 

1-7570 

68-49 

84 

1-2490 

27-72 

34 

1-819 

72 

253 

1-7360 

6686        82 

1-2334 

26-09 

32 

1-810 

71 

245 

1-7120 

65*23        80 

1-2184 

24-46 

30 

1-801 

70 

238 

1-6870 

63-60        78 

1-2032 

22-83 

28 

1-791 

69      ' 

230 

1-6636 

61-97        76 

1-1876 

21-20 

26 

1-780 

68 

224 

1-6415 

60-34        74 

11706 

19-57 

24 

1-769 

67 

217 

1-6204 

58-71        72 

1-1549 

17-94 

22 

1-757 

66 

210 

1-5975 

5708   1     70 

1-1410 

16-31 

20 

1-744 

65 

205 

1-5760 

55-45   '     68 

11246 

14-68 

18 

1-730 

64 

200 

1-5503 

53-82 

66 

11090 

1305 

16 

1-715 

63 

195 

1-5280 

52-18 

64 

1-0953 

11-41 

14 

1-699 

62 

190 

1-5066 

50-55 

62 

1-0809 

9-78 

12 

1-684 

61 

186 

1-4860 

48-92 

60 

1-0682 

8-15 

10 

1-670 

60 

182 

1-4660 

47-29 

58 

1-0544 

6-52 

8 

1-650 

58-6 

177 

1-4460 

45-66 

56 

10405 

4-89 

6 

1-520 

50 

143 

1-4265 

44-03   i     54 

10268 

3-26 

4 

1-408 

40 

127 

1-4073 

42-40 

52 

1-0140 

1-63 

2 

1-300 

30 

115 

1-200 

20 

107 

MOO 

10 

103 

Tables  of  Richter  (StochiometriS  2,  802,)  of  Diz6  (J.  Chim.  Med,  8, 
100),  of  Anthon  (J.  pr.  Chem.  7,  70). 

IT  Bineau  {N.  Ann,  Chim,  Phys,  24,  337,)  gives  the  folloiving  table 
of  tbe  quantities  of  oil  of  vitriol  contaiDed  in  aqueous  sulphuric  acid  of 
different  densities.  The  numbers  marked  with  a  star  are  those  which 
were  determined  by  direct  experiment. 


188 


SULPHUR. 


OUofVitriol 

Sp.  gr. 

OilofVitriol 

Sp.  gr. 

:OilofVitriol 

Sp.gr. 

in  100  pt8. 

atO*»C. 

in  100  pts. 

at  0**C. 

;  in  100  ptfl. 

at  O^^C. 

0 

1000 

♦67-6 

1-600 

81 

1-759 

•3-86 

1-028 

68 

1-605 

82 

1-770 

5 

1035 

♦68-2 

1-608 

83 

1-781 

♦71 

1-051 

69 

1-617 

84 

1-791 

10 

1-073 

70 

1-628 

♦84-1 

1-792 

♦11-7 

1-086 

*70-3 

1-632 

85 

1-800 

15 

1-112 

71 

1-640 

86 

1-808 

♦17-5 

1131 

♦71-3 

1-643 

♦86-6 

1-813 

20 

1151 

♦71-7 

1-648 

87 

1-816 

♦21-4 

1-162 

72 

1-652 

88 

1-823 

25 

1192 

♦72-9 

1-663 

♦88-4 

1-828 

30 

1-232 

73 

1-664 

90 

1-830 

•32-2 

1-250 

♦73-1 

1-666 

91 

1-836 

35 

1-274 

*73-3 

1-6675 

92 

1-841 

40 

1-317 

74 

1-676 

93 

1845 

♦42-2 

1-336 

♦74-2 

1-6775 

93-5 

1-848 

45 

1-362 

*74-7 

1-685 

94 

1-8495 

♦48-9 

1-399 

75 

1-688 

♦94-5 

1-850 

50 

1-410 

♦75-5 

1-6935 

95 

1-851 

55 

1-460 

76 

1-700 

96 

1-852 

56-4 

1-475 

77 

1-712 

♦97-0 

1-853 

60 

1-514 

78 

1-724 

98 

1-8545 

*63-4 

1-553 

♦78-4 

1-729 

♦98-5 

1-855 

65 

1-570 

79 

1-736 

99 

1-8564 

66 

1-581 

80 

1-748 

100 

1-857 

67 

1-593 

♦80-2 

1-750 

If  it  be  required  to  determine  by  this  table  the  quantity  of  oil  of 
vitriol  contained  iu  a  sample  of  acid,  the  specific  gravity  of  which  has 
been  taken  at  any  temperature  above  zero,  a  correction  will  be  required 
to  bring  the  density  to  the  standard  temperature.  For  this  purpose  the 
following  data  are  given : 

Specific  Gravity  of  the  Decrease  of  the  Spec  Grav.  by  a  rise 

Add  at  O^C.  of  temp.  =  10*  C.  or  18*^  F. 

1-04  0-002 

1-07   0-003 

1-10   0.004 

1-15   0-005 

1-20   0-006 

1-30 0-007 

1-45   0-008 

1-70   0-009 

1-85   00096 

According  to  the  foregoing  table,  the  maximum  of  condensation  is 
found,  not  in  the  combination  of  1  At.  sulphuric  acid  with  3  At.  water, 
but  in  the  mixture  which  contains  75-5  parts  of  HO,  SO'  in  100  parts 
of  liquid.  IT 

b.  With  Boron  1—c.  With  Boracio  acid.— rf.  With  Phosphuretted 
Hydrogen. — e.  With  Nitric  oxide. 

/.  With  Salifiable  Bases.  Sulphates,  VUrioUy  Schwefelsaure  ScUze. 
Of  all  acids,  sulphuric  acid  has  the  strongest  affinity  for  the  greater 
number  of  salifiable  bases;  it  is  therefore  employed  to  separate  many 
other  acids  from  their  combinations  with  bases. — Oil  of  vitriol  will  not 
combine  with  baryta  unless  heat  be  applied;  the  anhydrous  acid,  on  the 
contrary,  and  likewise  the  hydrated  acid^  when  it  contains  either  more 


SULPHUniC  ACID.  189 

ot  less  water  than  oil  of  vitriol,  combines  rapidly  with  baryta,  even  at 
ordinary  temperatares.  (Vid,  Barium.)  The  vapour  of  anhydrous  sul- 
phuric acid,  or  of  oil  of  vitriol  exerts  scarcely  any  decomposing  action  on 
calcspar.  (^Vid.  Calcium.)  Oil  of  vitriol  mixed  with  6  parts  of  absolute 
alcohol  neither  reddens  litmus  nor  decomposes  any  anhydrous  carbonate ; 
but  it  decomposes  acetates  with  facility.  {Vid,  Alcohol.) — The  combina- 
tion of  sulphuric  acid  with  salifiable  bases  is  attended  with  considerable 
evolution  of  heat,  sometimes  rising  even  to  ignition :  e.  g.  with  baryta  and 
magnesia. 

There  exist  mon-acid,  bi-acid,  and  ter-acid,  besides  a  few  basic  sul- 
phates. The  normal  salts  of  the  alkalis,  magnesia,  protoxide  of  manga- 
nese, and  oxide  of  silver,  are  neutral ;  the  rest  redden  litmus.  The  normal 
salts  which  contain  a  volatile  base  (ammonia)  are  decomposed  at  a  red 
beat ;  those  which  contain  a  fixed  base,  and  are  held  together  by  a  strong 
affinity,  are  unaltered  by  ignition  (fixed  alkalis,  magnesia,  oxide  of  lead.) 
When,  on  the  other  hand,  the  affinity  between  the  acid  and  base  is 
weaker,  water,  if  present,  is  first  driven  off*, — and  then  ^the  anhydrous 
sulphuric  acid  is  evolved,  partly  in  the  unaltered  state,  partly  in  the  form 
of  sulphurous  acid^  and  oxygen  (sulphates  of  antimony,  zinc,  copper, 
and  ferric  oxide); — or  if  tne  affinity  be  so  weak  as  to  allow  of  the 
volatilization  of  the  acid  before  all  the  water  is  driven  ofi*,  oil  of  vitriol  is 
evolved  (sulphate  of  gold^.  A  very  high  temperature  is  required  to  separate 
the  last  portions  of  sulphuric  acid  from  the  oxides  of  zinc,  cadmium, 
cobalt,  nickel  and  copper. — If  the  base  has  a  tendency  to  take  up  more 
oxygen  (ferrous  oxide),  it  abstracts  oxygen  at  high  temperatures  from  the 
sulphuric  acid,  thereby  converting  it  into  sulphurous  acid;  the  oxides  of 
the  noble  melals,  on  the  contrary,  give  up  their  oxygen,  and  are  reduced 
to  the  metallic  state. 

All  sulphates  are  decomposed  by  ignition  with  charcoal.     Treated  in 
this  manner,  sulphate  of  magnesia^ — and  likewise  sulphate  of  zinc,  at  a 
moderate  heat — are  resolved  into  metallic  oxide,  and  a  mixture  of  two 
measures  of  sulphurous  acid  and  one  of  carbonic  acid  gas. 
2  (MgO,  S0»)  +  C  =  2MgO  +  2S0*  +  C0«. 

The  sulphates  of  bismuth,  silver,  and  protoxide  of  mercury — and  at  a 
gentle  heat  also  the  sulphate  of  copper — are  resolved  into  reduced  metal 
and  equal  volumes  of  sulphurous  and  carbonic  acid  gases]: 
AgO,  SO'  +  C  =  Ag  +  S0«  +  CO* ; 

Sulphate  of  lead,  and  at  a  strong  heat,  also  the  sulphates  of  copper  and 
zinc,  are  resolved  into  metallic  sulphide  and  carbonic  acid  gas. 
PbO,  SO>  +  2C  =  Pbs  +  2C0«; 

and  sulphate  of  manganous  oxide,  into  oxysulphide  of  manganese  and  1 
volume  of  sulphurous  acid  gas,  together  with  3  volumes  of  carbonic  acid 
4  (MnO,  S0>)  +  5C  =  2  (MnS,  MnO)  +  2SO»  +  5CO«? 

(Gay-Lussac.)  The  fixed  alkaline  sulphates  are  reduced  in  a  similar  man- 
ner to  sulphate  of  lead,  at  least  at  a  white  heat  (Berthier,  Ann,  Ohim, 
Phyt,  22,  229),  monosulphide  of  the  metal  and  carbonic  acid  gas  being 
produced ; — ^but  the  latter  is  more  and  more  replaced  by  carbonic  oxide,  in 
proportion  to  the  quantity  of  charcoal  with  which  the  sulphate  has  been 
mixed.  (Clement  &  Desormes,  GUb.  9,  422.)  At  a  red  heat,  on  the 
contrary,  part  of  the  alkali  remains  undecomposed — the  quantity  being 
greater  as  the  temperature  is  lower — and  a  sulphide  is  produced  con- 


190  SUIJ>HUR. 

taining  iDore  than  1  atom  of  sulphur  to  1  atom  of  metal,  and  couBequently 
forming  a  yellow  solution  when  dissolved  in  water.  (Gay-Lussac^  Ann. 
Chim,  PhyB.  80^  24.)  Sulphates  fused  with  carbonate  of  so<la  upon  charcoal 
before  the  blow-pipe  yield  a  mass  which  contains  sulphide  of  sodium,  and 
when  moistened  with  water  and  placed  upon  silver  foil,  blackens  it  im- 
mediately; it  also  evolves  siilphretted  hydrogen  when  treated  with  acids. 
(Smithson.)  Fused  upon  charcoal  with  carbonate  of  soda  and  glass  (or 
silica)  they  form  a  besul  which  is  colourless  or  dark  brown  while  hot,  but 
on  cooling  acquires  a  red  or  yellow  tint, — and  if  much  sulphide  of  sodium 
is  present,  becomes  opaque.  (Gabn.)  Both  these  reactions  are  likewise 
exhibited  by  the  salts  of  hyposulphurous,  pentathionio,  tetrathionic,  tri- 
thionic,  snlphurous,  and  hyposulphuric  acid. 

On  f>aasing  hydrogen  gas  through  a  red  hot  tube  containing  an  inor- 
ganie  sulphate,  water  is  produced,  together  with  either  a  metallic  sulphide 
^as  in  the  case  of  potassa,  Sch,  84),  or  a  compound  of  sulphide  and  oxide 
le.  g.  protoxide  of  manganese.  Arfvedson,  Fogg,  1,  49),  or  an  oxide  alone 
(magnesia). 

Boron  and  phosphorus  act  in  the  same  manner  as  carbon  and  hydro- 
gen, sometimes  with  formation  of  a  borate  or  phosphate.  Sulphates  are 
also  decomposed  by  potassium,  sodium,  manganese,  antimony,  zinc,  tin, 
and  iron. 

f  Sulphate  of  potassa  is  completely  decomposed  by  igniting  it  for  a 
short  time  with  finely  divided  iron.  A  blackish  porous  mass  is  obtained, 
consisting  of  sulphide  and  oxide  of  iron  and  caustic  potassa. 

KO,  S0»  +  3Fe  =  KO  +  Fe»0>  +  FeS 

The  same  salt  ignited  with  excess  of  zinc,  yields  a  compact  lemon-yellow 
coloured  mass  consisting  of  sulphide  of  potassium  and  oxide  of  zinc. 

KO,SO»  +  4Zn  r=  KS  +  4ZnO 

Sulphate  of  soda  exhibits  similar  reactions.  When  a  solution  of  sul- 
phate of  ammonia  is  boiled  in  contact  with  iron,  ammonia  is  evolved,  and 
the  solution  is  afterwards  found  to  contain  a  salt  of  ferrous  oxide.  On 
fusing  the  mixture  at  a  gentle  heat,  the  evolution  of  ammonia  is  stronger  and 
the  ^t  assumes  a  dark  colour,  and  gives  a  greenish  solution  in  water. 
If  the  mixture  be  suddenly  heated  to  redness,  sulphurous  acid  esci^>es 
together  with  the  vapour  of  the  salt,  and  the  surface  of  the  iron  becomes 
covered  with  sesqui-oxide^  and  sometimes  also  with  sulphide.  These 
products  appear  however  not  to  be  formed  directly,  but  to  result  from 
the  decomposition  of  ferrous  sulphate  produced  by  the  fusion.  Zinc  ex- 
hibits similar  results.  Sulphate  of  lime  ignited  with  iron  in  a  porcelain 
crucible  yields  a  greyish  black  mass  of  metallic  aspect,  containing  sulphide 
of  calcium  and  an  oxide  of  iron.  The  two  following  reactions  appear  to 
take  place  at  the  same  time : 

(1.)     CaO,SO>  +  3Fe=    CaS  +     Fe«  O* 
(2.)  3CaO,  SO»  +  8Fe  =  3CaS  +  4Fe«  0> 

Sulphate  of  lime  ignited  with  pure  zinc  yields  a  yellowish  scaly  mass  con- 
taining lime,  together  with  oxide  and  sulphide  of  zinc,  but  no  sulphide  of 
calcium : 

CaO,  S0»  +  4Zn  =  CaO  +  3ZnO  +  ZnS. 

The  sulphates  of  baryta  and  strontia  give  similar  results :  a  higher  tem- 
perature is  however  required  for  the  decomposition  of  sulpliate  of  strontia 
by  iron.  Sulphate  of  magnesia  ignited  with  iron  evolves  a  considerable 
quantity  of  sulphurous  acid,  and  forms  a  mass  haying  an  iron-grey  aqpect 


SULPHURIC  ACID.  lOl 

and  containing  white  lamps  of  magnesia  here  and  there.  The  iron  is 
conyerted  into  protoxide  and  sesqui-oxide  with  a  portion  of  sulphide.  In 
these  decompositions  it  is  especially  remarkable  that,  in  those  oases  in 
which  the  iron  takes  up  both  constituents  of  the  sulphuric  acid,  the  zinc 
combines  only  with  the  oxygen;  and  where  the  zinc  is  conyerted  into 
both  oxide  and  sulphide,  the  iron  does  not  enter  into  combination 
with  the  sulphur,  but  only  with  the  oxygen.  (Albert  d'Heureuse,  Fo^g. 
75,  255.)  IT 

Dilute  aqueous  solutions  of  alkaline  sulphates  are  conyerted  inte 
alkaline  hydrosulphates  or  metallic  sulphides  by  organic  substances  dis- 
solyed  in  or  diffused  through  them.  (Kastner,  Kastn,  Arch.  1,  360.)  The 
sulphur  giyes  it  up  its  oxygen  to  the  carbon  and  hydrogen  of  the  organic 
substance,  and  takes  hydrogen  from  it;  or,  on  the  other  hypothesis,  the 
sulphuric  acid  and  alkali  are  both  depriyed  of  their  oxygen.  A  solution 
of  sulphate  of  soda  in  about  500  parts  of  water,  or  a  saturated  solution  of 
gypsum,  mixed  with  a  little  sugar,  gum,  or  ^lycyrrhizin,  and  kept  from 
half  a  year  to  two  years  in  a  close  yessel,  is  found  to  contain  hydro- 
sulphuric,  carbonic,  and  acetic  acid,  the  two  former  partly  free,  partly 
in  combination  with  soda  or  lime.  This  explains  the  occurrence  of 
acetic  acid  in  many  mineral  waters.  A  peculiarly  rapid  decomposition 
has  been  found  to  be  produced  by  water  which  has  stood  for  six  months 
in  contact  with  beechwood.  (A.  Vogel,  Kastn,  Arch,  15, 306.)  A  piece 
of  straw  placed  in  a  yessel  filled  with  a  mineral  water,  deyelops  hydro- 
sulphuric  acid,  if  the  air  has  access  to  the  liquid  (the  air  probsubly  facili- 
tating the  decomposition  of  the  straw),  but  not  if  the  air  is  completely 
excluded.  Many  mineral  waters  alreaidy  contain  organic  matter  in  solu- 
tion, so  that  the  addition  of  such  matter  to  them  is  superfluous.  (Kastner.) 
Such  is  the  case  with  the  gypsum-water  of  Berka.  (Dobereiner,  JSchw, 
8,  461.)  Water  from  Passy,  which  contains  sulphate  of  lime  and  other 
sulphates,  together  with  organic  matter,  was  found,  after  beinfi;  kept 
for  a  year  in  jugs  placed  in  a  cellar,  to  be  rich  in  hydrosuTphurie 
acid;  and  all  the  ferrous  carbonate  which  it  contained,  was  conyerted 
into  a  black  powder,  consisting  of  monosulphide  of  iron  (or  ferrous 
hydrosulphate) ;  slimy  flakes  of  an  azotizea  organic  substance  were 
likewise  found  in  it.  (0.  Henry,  J,  Fharm.  1 3,  208.)  Gypsum  from  the 
neighbourhood  of  Paris,  which  is  thoroughly  impregnated  with  organic 
matter,  deyelops  hydrosulphuric  acid  when  placed  in  bottles  with  water. 
(0.  Henry,  J.  Fharm,  22,  596.)  The  formation  of  hydrosulphuric  acid  in 
mineral  waters  which  haye  been  kept  for  some  time  in  contact  with 
organic  matter  is  likewise  confirmed  by  Bischof  (Schw,  57,  30.)  Many 
sulphur-springs  doubtless  deriye  their  hydrosulphuric  acid  from  the  de- 
composition of  alkaline  [sulphates  by  organic  matter  taking  place  in  the 
earth.  The  alteration  wnich  takes  place  by  long  keeping  in  a  wet  mass 
of  porcelain  clay  containing  gypsum  and  organic  matter,  may  likewise  be 
explained  in  the  same  manner.  In  hot  climates,  as  on  the  West  Coast  of 
Africa,  where  the  water  of  the  riyers  highly  charged  with  organic  matter, 
mixes  with  the  sea-water  which  contains  salts  of  sulphuric  acid,  the  same 
decomposition  takes  place— extending  sometimes  to  a  distance  of  27  mile^ 
from  the  mouths  of  the  riyers.  The  water  contains  hydrosulphuric  acid, 
sometimes  as  much  aa  six  cubic  inches  in  a  gallon;  hence  it  exerts  a  pecu- 
liarly rapid  action  on  the  copper  sheathing  of  ships,  and  its  eyaporation 
giyes  rise  to  malignant  foyers.  The  same  miasma  is  produced  when  sea- 
water  mixes  with  fresh  water  upon  land.  According  to  Daniell,  the  hy- 
drosulphuric acid  itself  is  the  miasma;  hence  chlorine  is  efficacious  in  de- 


192  SULPHUR. 

stroying  it.  (Ann.  Chim.  Phys,  78,  331.)  But  if  that  were  tlie  case, 
chemists,  as  well  as  persons  liviDg  in  the  neighbourhood  of  sulphur-springs 
would  be  often  attacked  with  malignant  fevers.  The  presence  of  hydro- 
sulphuric  acid  may  however  facilitate  the  development  of  the  miasma, 
which  is  undoubtedly  something  organic.  {Gm.) 

MtLJiy  fixed  acids,  as  phosphoric,  boracic,  and  silicic  acid,  though  endued 
with  less  affinity  than  sulphuric  acid  has  for  salifiable  bases,  nevertheless 
decompose  sulphates  at  various  degrees  of  ignition,  combining  with  the 
base  of  the  salt  and  expelling  the  sulphuric  acid,  sometimes  unaltered, 
sometimes  resolved  into  sulphurous  acid  and  oxygen.  Hydrochloric  anS 
nitric  acid  deprive  the  normal  sulphates  of  ammonia,  potassa,  and  soda  of 
half  their  base,  giving  rise  to  the  formation  of  an  alkaline  bisulphate. 
(I.,  126,  127)  On  the  other  hand,  the  sulphates  of  magnesia,  alumina, 
oxide  of  sine,  protoxide  of  iron,  oxide  of  nickel  and  protoxide  of  mercury, 
crystallize  unaltered  from  solution  in  hydrochloric  acid;  and  hydrochloric 
acid  gas  passed  over  dry  sulphate  of  potassa,  soda,  magnesia,  alumina,  oxide 
of  zinc,  oxide  of  lead  or  protoxide  of  iron,  exerts  no  action; — ^the  sulphates 
of  oxide  of  nickel  and  protoxide  of  mercury  absorb  half  an  atom  of  hydro- 
chloric acid,  which  is  evolved  on  the  application  of  heat  and  likewise  ex- 
tracted by  water. 

The  normal  sulphates  of  sesqui-oxide  of  antimony,  protoxide  of  bis- 
muth, protoxide  of  mercury,  and  di-oxide  of  mercury  are  resolved  by  con- 
tact with  water  into  dilute  acid  and  residual  basic  salts.  The  sulphates  of 
ma^esia,  zinc  and  nickel  and  the  protosulphates  of  manganese,  iron,  cobalt 
and  copper,  which  crystallize  in  combination  with  water,  retain  one  atom 
of  their  combined  water,  the  saline  or  canetUutional  water,  (II.,  65)  much 
more  strongly  than  the  remaining  atoms,  not  parting  with  it  in  fact,  till 
they  are  heated  to  204^  (400°  F.).  This  atom  of  water  is  likewise  separ 
rated  at  lower  temperatures  by  the  introduction  of  another  salt  of  sulphuric 
acid,  which  forms  a  double  salt  with  the  former :  e.  g.  ZnO,  SO^  +  HO 
is  converted  by  KO,  SO*  into  ZnO,  SO'  +  KO,  S0»,  the  water  being 
liberated ;  hence  it  appears  that  the  constitutional  water  plays  the  part  of 
a  salt.  (Graham,  Phil,  Mag.  J.  6,  329 ;  also  J.  pr,  Chem.  6,  50. — Ann. 
Pharm,  29,  27.)  All  bisulphates  and  tersulphates  are  either  soluble  in 
water,  or  are  resolved  by  it  into  hydrated  sulphuric  acid  and  a  simple 
salt.  Basic  sulphates  are  insoluble  in  water,  but  soluble  in  dilute  hydro- 
chloric acid.  Normal  sulphates  are  mostly  soluble  in  water;  the  lime 
and  silver  salts  however  are  but  slightly  soluble,  and  the  strontia,  baryta, 
and  lead  salts  scarcely  at  all ;  moreover,  their  solubility  is  not  sensibly 
increased  by  the  addition  of  sulphuric  acid  to  the  water.  The  sulphates 
of  baryta  and  strontia,  on  the  contrary,  are  soluble  to  a  considerable 
extent  in  oil  of  vitriol,  and  precipitated  from  the  solution  on  the  addition 
of  water. 

All  soluble  sulphates,  as  well  as  basic  sulphates  dissolved  in  hydro- 
chloric acid,  give  with  soluble  salts  of  baryta,  a  white  precipitate,  insoluble 
in  dilute  nitric  or  hydrochloric  acid.  A  solution  of  sulphate  of  potassa, 
containing  one  part  of  sulphuric  acid  in  50,000  parts  of  water,  gives  a 
slight  turbidity  with  nitrate  of  baryta,  and  very  slight  with  nitrate  of 
lead;  with  1  part  of  acid  in  100,000  of  water,  the  former  reagent  gives  a 
very  slight  turbity,  the  latter  none ;  with  the  same  quantity  of  salt  in 
200,000  parts  of  water,  nitrate  of  baryta  gives  a  very  slight  cloudiness 
after  the  lapse  of  15  or  20  minutes;  and  in  400,000  parts  of  water,  none 
at  all.  (Lassaigne,  J.  Chim.  Med.  8,  522.)  When  sulphates,  insoluble  in 
water,  are  boiled  in  solution  of  carbonate  of  soda,  the  filtered  liquid  super- 


HTDROSULPHUROUS  ACID.  J  93 

sainrated  with  hydrochloric  acid  likewise  precipitates  baryta  salts.  Most 
sulphates  are  insoluble  in  alcohol. 
g.  With  many  organic  substances. 


Sulphur  and  Hydrogen. 
A.    Hydrosulphurous  Acid.    HS*. 

FernUphide  of  Hydrogen,    WasterOof'ickwefel,    WasserOof-iuperstUfur 
Hydrotkionige  Sdure^  Hydrure  de  soufre,  Soufre  hydrogine. 

Formation.  Under  the  following  circumstances,  solutions  are  formed 
which  may  be  supposed  to  contain  either  an  alkaline  hydrosulphite  oi 
a  peutasulphide  of  the  corresponding  metal :  I.  When  pentasulphide  of 
potassium  or  sodium  is  dissolved  in  water : 

KS»  +  HO  =  KO,  HS». 

2.  When  the  aqueous  solution  of  the  monosulphide  of  an  alkali-metal,  or 
—what  comes  to  the  same  thing — an  alkaline  hydrosulphate,  is  digested 
with  sulphur,  of  which  it  dissolves  4  atoms : 

KS  +  4S  «  KS»:  or:  KO,  HS  +  4S  «  KO,  HS». 

3.  When  a  solution  of  the  kind  just  mentioned  is  exposed  to  the  air  (vid. 
Metallic  Sulphides),  — 4,  When  sulphur  is  boiled  with  the  aqueous 
solution  of  a  fixed  alkali^  a  hyposulphite  being  formed  at  the  same  time : 

3CbO  +  12S  =  2C»S*  +  CaO,  S«0«; 
or:  3CaO  +  12S  +  HO  =  2  (CaO,  HS*)  +  CaO,  S«0«. 

5.  Hydrosulphite  of  ammonia  appears  to  be  sometimes  produced  in 
the  putrefaction  of  organic  substances  containing  sulphur. 

Freparation.  1.  A  concentrated  solution  of  pentasulphide  of  potas-* 
Slum,  obtained  by  fusing  carbonate  of  potassa  with  excess  of  sulphur,  is 
poured  by  small  portions  at  a  time  into  a  lukewarm  mixture  of  hydro^ 
chloric  acid  and  water.  (Berzelius.) 

KS*  +  Ha  =  KQ  +  HS5. 
To  obtain  pentasulphide  of  potassium,  Liebig  heats  2  parts  of  carbonate 
of  potassa  with  1  part  of  sulphur  to  a  state  of  red-hot  fusion,  dissolves 
the  fused  mass  when  cool  in  water,  saturates  the  solution  at  a  boiling 
heat  with  sulphur,  and  filters. — 2.  One  part  of  lime  burned  and  slaked, 
is  boiled  with  2  parts  of  sulphur  and  16  of  water;  and  this  solution,  after 
cooling  and  filtering,  is  poured  into  an  excess  of  dilute  hydrochloric  acid. 
Th^nard  boils  the  lime  for  a  considerable  time  with  excess  of  sulphur, 
and  pours  the  filtrate  slowly,  stirring  all  the  while,  into  a  mixture  of  one 
part  commercial  hydrochloric  acid  and  2  parts  water.  Liebig  boils  one 
part  of  lime  and  1  part  of  sulphur  in  16  parts  of  water,  and  pours  the 
filtrate  at  once  into  half  its  bulk  of  a  mixture  of  2  parts  fuming  hydro- 
chloric acid  and  1  part  water.  Since  the  hydrochloric  acid  decomposes 
not  only  the  pentasulphide  of  calcium  or  hydrosulphite  of  lime,  but  like- 
wise the  hyposulphite  of  lime,  and  since  the  hyposulphurous  acid  thus 
set  free  is  gradually  resolved  into  sulphurous  acid  and  sulphur,  the 
sulphur  necessarily  becomes  mixed  with  the  precipitated  hydrosulphurous 
acid.  Hence,  according  to  Th^nard,  the  portions  of  hydrosulphurous 
VOL.  ir.  o 


104  8ULPHUS. 

aoid  first  precipitated  are  more  flaid  than  tlioia  which  are  deposited 
afterwards. 

In  both  modes  of  preparation,  the  hydrosulphurous  acid  separates  in 
fine  drops,  which  produce  a  milky  turbidity  in  the  liquid,  and  collect  at 
the  bottom  in  the  form  of  an  oily  liquid.  Thenard  performs  the  precipita- 
tion in  a  funnel,  the  neck  of  which  is  furnished  with  a  stopper,  so  that 
the  precipitated  acid  may  be  let  out  at  pleasure. 

Properties.  Yellow,  transparent,  oily,  li(|aid,  having  the  consistence 
of  thin  oil,  when  it  contains  a  minimum  quantity  of  sulphur,  and  that  of  a 
viscid  oil,  when  the  quantity  of  sulphur  is  larger :  in  the  latter  case,  its 
density  is  1-780.  (Thenard.)  It  has  a  peculiar,  sulphurous,  disagreeable 
odour,  and  irritates  the  nose  and  eyes.  Tastes  sweet  and  bitter,  and 
imparts  a  white  colour  to  the  tongue  and  saliva.  A  few  drops  placed 
npon  the  skin  of  the  arm,  alter  and  decolorize  it  (Th6nard.}  At  the 
moment  of  its  precipitation,  according  to  method  2,  it  bleaches  litmus 
paper  introduced  into  the  milky  liquid.  (Thenard.) 


68. 
H  . 

Calcalation. 

80  98-76 

1  1-24 

Or: 

4S  

HS    . 

...  64  ... 

..  17  ... 

79-01 

....  20-99 

HS» 

....  81  100-00 

HS»  . 

..  81  ... 

....100-00 

(H«S*  »  2 . 6-24  +  5 .  201*17  »  1018-33.    Bendiu.) 

In  eonseqnence  of  the  excess  of  sulphur  always  mixed  with  Ala  cora- 
ponndy  analysis  gives  6  or  8  atoms  of  sulphur  instead  of  five.  (Thenard.) 

Decompositione.  1.  The  acid,  if  left  to  itself  for  a  few  days,  is  resolved 
into  hvdrosulphuric  acid,  which  escapes  as  gas,  and  sulphur,  which  remains 
behinc^  so  that  the  liquid  becomes  more  and  more  viscid,  and  ultimately 
solid.  The  decomposition  is  more  rapid  at  60°,  and  still  more  so  at 
100°.  (Th6nard.)  Even  when  this  compound  is  sealed  up  in  a  glass 
tube,  it  resolves  itself  completely,  in  the  course  of  three  weeks,  into 
transparent  crystals  of  sulphur  and  colourless  liquid  hydrosulphuric  acid. 
(Kemp,  FhU.  Mag.  J.  7,  444;  also  Ann.  Pharm.  28,  170;  Liebig.)  The 
decomposition  in  the  sealed  tube,  however,  does  not  take  place  unless 
water  is  present;  so  that  by  adding  a  little  chloride  of  calcium  to  the 
hydrosulphurous  acid,  it  may  be  kept  in  the  tube  unaltered.  (Bunsen, 
Pogg.  46,  103.)  Acids  prevent  the  decomposition:  the  liquid,  when 
immersed  in  hydrochloric  acid,  will  remain  for  a  long  time  in  open  vessels 
without  alteration.  Even  on  boiling  it  with  the  aqueous  solution  of  an 
acid,  the  decomposition  takes  place  very  slowly;  and  after  the  greater 
part  of  the  hydrosulphuric  acid  has  escaped,  the  vapours  exert  a  peculiar 
irritating  action  on  the  nose  and  eyes.  (Berzelius.)  On  the  other  hand, 
decomposition  is  accelerated  by  the  toUowing  substances:  a.  Finely 
divided  charcoal,  silica,  manganese,  kermes-mineral,  galena,  sulphide  of 
gold,  gold,  platinum,  and  other  metals ;  also  by  sugar,  starch,  and  lignin, 
which  however  exert  but  a  very  feeble  action.  (Thenard.)  Silica  and 
kermes-mineral,  in  the  state  of  powder,  produce  a  slight  disengagement 
of  gas  at  the  particular  points  in  which  thev  touch  the  liquid ;  but  if  pre- 
viously wetted,  they  do  not  produce  this  effect.  (Liebig.) — h.  Penta- 
sulphide  of  potassium,  either  in  solution  or  diffused  through  water,  causes 
a  very  violent  evolution  of  hydrosulphuric  acid  fas,  and  sudden  precipi- 
tation of  sulphur,  (Thenard.)  Alcoholic  solution  of  liver  of  sulphur 
Ukewise  effects  the  decomposition,  without  evolution  of  hydrosulphuric 


HYDROSULPHUBOUS  ACID.  195 

aoid.  (Liebig.)— «.  Decomposition  is  also  brought  abont  by  powdered 
hydrate  of  potassa,  baryta^  strontia^  lime,  or  magnesia;  likewise  by 
aqueous  solution  of  ammonia  or  potassa.  (The  potassa,  according  to  the 
earlier  observation  of  Berselius,  is  thereby  converted  into  sulphide  of 
potassium,  or  hydrosulphate  of  potassa.)  These  substances  perhaps  form 
metallic  sulphides  in  the  first  instance,  and  the  sulphides  exert  the  decom- 
posing action.  (Th6nard.)  With  a  small  quantity  of  solution  of  potassa, 
hydrosulphurous  acid  evolves  sulphuretted  nydrogen  gas :  with  an  excess 
of  the  alkali,  it  is  at  once  converted  into  soft  spongy  sulphur,  which 
evolves  but  few  bubbles  of  sas.  In  excess  of  aqueous  solution  of  ammonia, 
it  is  immediately  converted,  with  frothing  and  decrepitation,  into  brittle, 
blistered  sulphur;  the  liquid  is  found  to  contain  sulphide  of  ammonium, 
with  more  than  1  atom  of  sulphur,  f  Liebig.) — d.  Mixed  with  finely  pounded 
chloride  of  calcium,  it  froths  up  violently  and  becomes  solid  after  a  time. 
Effloresced  Glauber  s  salt  acts  more  slowly ;  the  same  salt  in  the  crys- 
tallized state,  not  at  all.  Some  of  the  above-mentioned  substances  probably 
act  by  abstracting  water.  (Liebig.) — e.  Water  agitated  with  hydrosul- 
phurous acid,  takes  hydrosulphuric  acid  from  it,  and  becomes  milky. 
Alcohol  appears  to  act  m  a  similar  manner.  Ether  dissolves  it  at  first, 
but  soon  deposits  white  acicular  crystals  of  sulphur,  which  become  yellow 
when  dry. 

2.  Hydrosulphurous  acid  may  be  set  on  fire  by  the  flame  of  a  candle, 
and  bums  with  a  blue  flame. 

8.  Oxide  of  silver  and  oxide  of  gold  placed  in  contact  with  this  sub- 
stance, become  red  hot,  water  being  formed,  and  the  oxide  reduced  to 
the  metallic  state.  (Th^nard.)  Oxide  of  silver  is  converted  into  sul- 
phide. (Liebig.) 

Comfnnaiions,  Hydrosulphurous  acid  appears  to  be  insoluble  in 
water.  It  combines  with  certain  salifiable  iMUBesf  forming  salts,  called 
Jffydrothumites.     (Vid.  Metallic  Sulphide:) 


B.    Htbrosulphuric  Acid.    HS. 

Sulphuretted  Hydrogen,  Sulphide  of  Hydrogen,^  HydroHiiofu&ure^ 
ffydrothion,  Hydrogene  Sulfur^,  Adde  hydrosvlphurigue,  Acide  sulfhy- 
drique,  Sulfide  hydrique,  Hydrogenium  sulphuratum;  and  in  the  gaseous 
state:  Hydrosulphuric  acid  gas,  Sulphuretted  Hydrogen  gas,  Hepatic  air^ 
Hydrothionsaures  Gas,  Hydrothion  Gas,  Schwefelleberlvft,  Gas  hydrogine 
Sulfur^,  Gas  hydrogenium  sulphuratum.  Exists  in  hepatic  waters,  in 
sea^water  near  the  mouths  of  certain  rivers  (II.  192),  in  putrid  eggs,  and 
in  sewers. 

Formation.  1.  When  sulphur  is  heated  to  the  subliming  point  for  a 
considerable  time  in  hydrogen  gas,  or  when  hydrogen  is  passed  over 
melted  sulphur,  combination  takes  place  between  the  two,  but  very  slowly 
and  imperfectly,  so  that,  even  after  the  process  has  been  continued  for  a 
long  time,  a  considerable  quantity  of  hydrogen  remains  uncombined. 
The  volume  of  the  gas  remains  unaltered.  (Scheele,  H.  Davy.) — 2.  On 
bringing  various  metallic  sulphides  in  contact  with  dilute  acids,  the  metal 
takes  oxygen  from  the  water,  and  forms  an  oxide  which  dissolves  in 
the  acid,  while  the  hydrogen  of  the  water  enters  into  combination  with 
the  sulphur : 

FeS  +  HO  +  SO'  -  PcO,SO'  +  HS. 

o  2 


196  SULPHTJIU 

In  the  ease  of  hydrogen  acids,  it  is  simpler  to  snppose  that  the  radical  of 
the  acid  is  transferred  to  the  metal  and  its  hydrogen  to  the  sulphur; 
thus: 

FeS  +  HQ  ^  FeQ  +  HS. 

3.  When  organic  compounds  containing  sulphur  putrefy  or  are  heated 
by  themselves;  or  when  other  or^nic  compounds  are  heated  in  contact 
with  sulphur.  If  the  existence  of  hydrogen-salts  of  metallic  oxides  be 
admitted,  it  must  likewise  be  supposed  that  hydrosulphuric  acid  is  gene- 
rated when  a  monosulphide  of  an  alkali-metal  is  dissolved  in  water,  and 
when  iron  filings  are  mixed  with  water  and  sulphur. 

Preparation,  1,  In  the  gageous  stale: — a.  Oil  of  vitriol  diluted 
with  about  eight  times  its  quantity  of  water,  either  at  the  temperature  of 
the  air  or  a  little  above  it,  is  put  into  a  gas-generating  vessel  (App.  40), 
together  with  one  of  the  followiog  substances :  Monogidphide  of  iron : 
this  substance  evolves  the  gas  slowly  and  continuously,  but  generally 
mixed  with  hydrogen :  Hydrated  Monotvlphide  of  iron^  or  kydrosulphale 
of  protoxide  of  irony  prepared  by  heating  for  a  short  time,  and  out  of 
contact  of  air,  a  mixture  of  1  part  flowers  of  sulphur,  2  parts  iron  filings, 
and  a  quantity  of  water  sufficient  to  make  it  into  a  paste  (Tourte,  BerL 
Jahrb.  18,  202;  Gay-Lussac,  Ann,  Chim,  Phys,  7,  314):  evolves  the  gas 
very  rapidly,  and  generally  mixed  with  free  hydrogen,  the  action  is  soon 
over ;  this  hydrated  sulphide  cannot  be  kept  long.  Sulphide  of  calcium, 
prepared  by  igniting  3  parts  of  gypsum  with  1  part  of  charcoal,  in  a 
covered  crucible:  evolves  the  gas  rapidly  and  in  abundance;  cannot  be 
kept  very  long.  Potash  liver  of  sulphur  (the  old  method).  Impure  sul- 
phide  of  manganese,  obtained  by  igniting  6  parts  of  sulpnate  of  manga- 
nese with  1  part  of  charcoal  (Bertbier),  or  5  parts  of  ignited  oxide  of 
manganese  with  2  psrts  of  sulphur  and  1  part  of  charcoal:  evolves  the 
gas  very  rapidly;  spoils  by  long  keeping.  Sulphide  of  iron  and  sodium, 
prepared  by  fusing  2  parts  of  iron  pyrites  with  1  part  of  anhydrous 
carbonate  of  soda.  (Berthier.)— i.  By  heating  tersulphide  of  antimony 
with  concentrated  hydrochloric  acid;  the  gas  is  not  evolved  in  very 
large  quantity,  but  it  is  free  from  hydrogen. — c.  By  heating  in  a  glass 
flask  a  mixture  of  equal  parts  of  sulphur  and  beef-suet.  By  this  method, 
the  gas  is  obtained  pure  and  with  slight  frothing;  when  it  is  wanted  for 
use,  the  flask  is  to  be  heated.  (Reinsch,  J,  pr.  Chem.  13,  142.; 

Hydrosulphuric  acid  gas  is  collected  over  warm  water  or  brine,  which 
absorb  less  of  it  than  pure  cold  water, — or  over  mercury. 

2.  In  the  liquid  state:  a,  Faraday's  method.  (I.,  286.)  The  sul- 
phide of  iron  must  be  freed  from  nncombined  iron  by  repeated  ignition 
with  sulphur ;  otherwise,  free  hydrogen  will  be  disengaged  and  the  tube 
will  be  burst.  (Niemann,  Br,  Arch,  Se,  189.)— 6.  Persulphide  of 
hydrogen  enclosed  in  a  sealed  tube  ffradually  resolves  itself  into  sul- 
phur and  hydrosulphuric  acid,  the  latter  assuming  the  liquid  state. 
(Kemp;  Liebic;  Bunsen,  II.  194.) 

IT  3.  In  me  solid  state:  By  Faraday's  process  (I.,  287.)  solidification 
takes  place  at— 122^  Fah. 

Properties.  1.  In  the  solid  state:  White,  crystalline,  translucent 
substance,  heavier  than  the  liquid;  it  occupies  the  same  place  in  the  sul- 
phur series  of  compounds  that  ice  does  in  the  oxygen  series.  IT 

2.  In  the  liquid  state:  Colourless,  transparent  liquid,  much  thinner 


HYDROSULPHURIC  ACID.  197 

and  less  adhesive  than  ether ;  specific  grayity  about  0*9  j  refracting  power 
higher  than  that  of  water.  Does  not  solidify  at—  17'8^  (Faraday: 
see  above,)  The  thinnest  of  all  liquids;  refracts  light  more  strongly 
than  sulphurous  acid  or  ammonia.  With  the  aid  of  heat  it  dissolves 
sulphur,  which,  on  cooling,  crystallizes  out  in  yellow  warty  masses, 
(Niemann.) 

3.  In  t/te  gcueow  state :  Tension,  sp.  gr.  and  refractive  power  of  the 
gas  (I.,  261,  279,  and  95).  Colourless.  Smells  like  rotten  eggs,  and 
produces  fainting  and  asphyxia,  even  when  mixed  with  the  air  in  very 
small  quantity :  when  inhaled  in  the  pure  state,  it  acts  as  a  powerful 
narcotic  poison.  Does  not  support  combustion,  but  is  itself  inflammable. 
Reddens  tincture  of  litmus  j  the  reddening  disappears  on  exposure  to 
the  air. 

BerzdiuB.  Th^nard  &        Th^nard 

Calculation.  earlier.  later,         Gay-Lnss.         (earlier.) 


s    . 

H    . 

16  941  .. 

1  5-9  .. 

......  93-8  .. 

6-2  .. 

94-176  ... 

5-824  ... 

93-855  70-857 

6-145  29-143 

HS 

17          100-0 
Salphnr  Tapour  ..... 

100-0 

Vol. 
1  

100000 

Sp.gr. 
..  6-6556     = 
..  0-4158     = 

100000          100-000 

Vol.          Sp.gr. 

}  M093 

1  0-0693 

Hydrogen  gas      .... 

6  

HydioBolph.  add  gas  ....  6  7-0714     =     1  11786 

(H*S  =  2  .  6-24  +  201-17  =  21365.    BerzeUus.) 

DecomposUions.  1.  Hydrosulphurio  acid  ffas,  passed  through  a  red- 
hot  porcelain  tube,  is  converted  into  pure  hydrogen  gas,  with  deposition 
of  sulphur.  (Cluzel,  Ann.  Chim.  84,  166) — 2.  Two  platinum  wires  made 
to  form  the  poles  of  a  powerful  voltaic  battery,  and  kept  in  a  state  of 
ignition  in  this  gas,  produce  the  same  action :  the  electric  spark  likewise 
acts  in  the  same  manner,  but  much  more  slowly.  The  volume  of  the  gae 
remains  unaltered.  (H.  Davy.) 

3.  Hydrosulphurio  acid  gas  bums  in  contact  with  air  or  oxygen 
under  the  same  conditions  as  hydrogen  gas.  It  may  be  inflamed  by 
charcoal  or  iron,  even  at  a  low  red  heat.  (H.  Davy.)  In  the  air  it  bums 
with  a  blue  flame,  forming  water  and  sulphurous  acid,  and  depositing 
sulphur;  mixed  with  oxygen  gas,  it  bums  with  explosion.  One  volume 
of  hydrosulphurio  acid  gas  exploded  with  half  a  volume  of  oxygen,  is 
completely  converted  into  water  and  sulphur,  because  half  a  volume  of 
oxygen  is  exactly  sufficient  to  convert  the  1  volume  of  hydrogen  con- 
tained in  1  volume  of  hydrosulphurio  acid  gas  into  water :  with  1^ 
vol.  oxygen,  it  is  completely  converted  into  water,  and  0*87  vol.  (in 
reality  1  voL)  of  sulphurous  acid  gas.  (Dal ton.)  In  this  case,  1  vol. 
oxygen  gas  combines  with  ^  vol.  sulphur  vapour  to  form  1  vol.  sulphu- 
rous acid  gas :  part  of  this,  however,  is  absorbed  by  the  water  which  is 
formed  at  the  same  time.^ — If  the  mouth  of  a  flask  in  which  hydrosulphurio 
acid  is  generated  be  connected  with  that  of  an  inverted  flask,  the 
bottom  of  which  has  been  removed,  so  that  a  mixture  of  air  and  sulphu- 
retted hydrogen  may  be  formed  in  it,  this  mixture  may  be  inflamed  by  a 
red-hot  coal,  burning  tinder,  red-hot  iron,  lava,  &c.,  but  not  by  ignited 
zinc,  copper,  or  glass.  The  combustion  is  attended  with  the  production 
of  a  thick  white  cloud,  which  spreads  out  from  the  ignited  body  through- 
out the  whole  mixture.  The  products  are,  water,  sulphurous  acid,  and 
sulphur.    Similar  fumes,  but  extending  to  the  dbtance  of  several  feet. 


198  SULPHUR. 

are  formed  ai  the  fumaroles  of  Agnauo,  near  Naples,  on  tbe  Itpproacli  of 
a  piece  of  lighted  tinder,  these  fumaroles  eyolving  hydrosulphuric  acid 
gas.  (Piria,  Ann.  Chim,  Phys,  74,  831.)  Spongy  platinum  does  not 
ignite  a  mixture  of  hydrosulphuric  acid  and  oxygen;  but  if  hydrogen 
be  likewise  present,  the  spongy  platinum  becomes  ignited  in  the  deto- 
nating gas,  and  then  sets  fire  to  the  sulphuretted  hydrogen.  (Dobereiner.) 
Platinum-paper-ash  or  paUadium-paper-ash  must  be  heated  to  about  lOO'^ 
before  it  will  attain  a  red  heat  in  a  stream  of  sulphuretted  hydr(^en  i 
it  then  sometimes  sets  the  gas  on  fire.  As  sulphur  is  in  that  case  depo- 
sited upon  the  ash,  it  must  be  cleaned  with  nitric  acid  before  it  will  act 
again.  (De  la  Rire  k  Marcet)  A  ball  of  platinized  clay  slowly  condenses 
a  mixture  of  hydrosulphuric  acid  and  oxygen,  with  formation  of  water, 
and  deposition  of  sulphur  on  the  platinum  baU,  by  which  it  is  gradually 
deprived  of  its  activity.  In  a  mixture  of  equal  measures  of  hydrosul- 
phuric acid,  hydrogen,  and  oxygen,  the  platinum  ball,  during  the  first 
24  hours,  induces  the  oxygen  to  combine  only  with  the  hydrogen  contained 
in  the  hydrosulphuric  acid,  the  free  hydrogen  not  entering  into  combina- 
tion with  the  oxygen  till  afterwards.  ^Graham,  N,  Qu,  J,  of  Sc.  6,  354.) 
IT  The  oxidation  of  sulphuretted  hydrogen  in  the  air  is  sometimes 
attended  with  the  formation  of  sulphuric  acid ;  the  presence  of  water 
appeals  however  to  be  essential  to  the  production  of  this  result.  Dumas 
(N.  Ann,  Chim,  Fhy$.  18,  502)  found  that  when  pieces  of  linen  or  cotton 
were  placed  in  a  glass  tube,  and  sulphuretted  hydrogen  mixed  with  air 
passed  through  the  tube,  no  sulphuric  acid  was  formed  at  ordinary  tem- 
peratures, if  the  gases  and  the  linen  were  dry;  but  if  the  linen  were 
wetted,  sulphuric  acid  was  produced.  On  heating  the  wet  linen  to  40 — 
50^  C.  (and  still  more,  if  it  were  heated  to  SO''  ~  90^)  considerable  quan« 
titles  of  sulphuric  acid  were  formed  in  the  course  of  fifteen  or  twenty 
minutes, — so  that  when  the  linen  was  afterwards  soaked  in  water,  the 
water  acquired  an  acid  reaction  and  gave  a  strong  cloud  with  chloride  of 
barium.  The  formation  of  sulphuric  acid  in  this  way  is  observed  at  the 
baths  of  Aix  in  Savoy.  The  walls  of  these  baths,  which  are  built  of 
limestone,  become  covered  after  a  while  with  crystals  of  gypsum ;  and 
iron  hooks  fixed  in  the  doors  are  soon  converted  into  green  vitriol.  Linen 
immersed  in  the  water  quickly  becomes  inpregnated  with  sulphuric  acid, 
—and,  in  the  course  of  a  few  weeks,  is  so  strongly  attacked  by  it,  as  to 
&11  to  pieces  on  being  dried  and  rubbed.  Now,  as  the  vapours  of  these 
baths  contain  no  sulphuric  acid,  and  do  not  even  redden  litmus,  the  effects 

iust  described  can  only  be  accounted  for  by  the  oxidation  of  sulphuretted 
Hydrogen  contained  in  the  water.  Phenomena  of  the  same  kind  are  often 
observed  in  volcanic  districts.  The  vapours  which  issue  from  the  fu- 
maroles of  Tuscany  contain  small  quantities  of  sulphuretted  hydrogen, 
but  no  free  sulphuric  acid :  nevertheless,  when  they  come  in  contact  with 
the  soil,  they  convert  the  carbonate  of  lime  therein  contained  into  sulphate. 
Humboldt  &  Boussingault  have  also  found  free  sulphuric  acid  in  the 
water  of  the  Rio  de  Pasambio,  not  very  far  from  the  volcano  of  Purace  in 
South  America.  (Ann.  Fharm.  60,  187.)  H 

4.  Oxygenised  bodies  decompose  hydrosulphuric  acid,  chiefly  by 
oxidating  the  hydrogen,  a.  Sulphurous  acid  gas  mixed  with  twice  its 
volume  of  hydrosulphuric  acid  gas  in  the  moist  state  (according  to  Cluzel^ 
no  action  takes  place  when  the  gases  are  dry)  condenses  to  a  yellow  sub- 
stance which  may  be  regarded  as  a  mixture  of  water  and  sulphur  {Sch.  69). 
Thomson  {Ann.  PhU.  12,  441)  regards  this  substance  as  sulphite  of 
snlphtiretted  hydrogen. — h.    When  hydrosulphuric  acid  gas  is  passed 


HYDROSULPHURIC  ACID.  199 

through  oil  of  ritrioli  water  is  formed  together  with  a  portion  of 
sulphurous  acid,  and  sulphur  is  deposited.  According  to  Dbbereiner 
{Sekw,  13,  481)  this  takes  place  only  with  the  Nordhausen  acid :  according 
to  A.  Vogel  (J,  pr,  Chem.  4,  2d2)|  the  same  action  is  also  produced  with 
rectified  oil  ot  ritriol^  and  likewise,  though  slowly,  in  a  mixture  of  the 
latter  with  ^  water,  but  not  in  a  mixture  of  1  pt.  oil  of  rittiol  and  4  pts. 
water;  in  the  latter  case,  no  turbidity  is  produced  unless  sulphurous 
acid,  arsenious  acid,  &c.  be  present.-— c.  Sulphuretted  hydrogen  takes  fire 
in  hypochlorous  acid  gas,  and  by  contact  with  concentrated  nitric  acid. 
With  peroxide  of  hydrogen,  its  aqueous  solution  is  resolved  into 
water  and  sulphur; — ^with  seletiious  acid,  into  water  and  selenide  of 
sulphur; — ^with  iodic  acid,  into  water,  sulphur,  and  iodine ; — with  alkaline 
iodates,  into  water,  sulphur,  sulphuric  acid,  and  iodine;— with  bromio 
acid,  into  water,  sulphur,  and  bromine;  with  alkaline  bromates,  into  water, 
sulphuric  acid,  and  bromine;  with  excess  of  hypochlorous  acid,  into 
water,  sulphuric  acid,  chlorine,  and  hydrochloric  acid ; — ^with  nitric  acid 
and  certain  nitrates,  into  water,  sulphur,  sulphuric  acid,  nitric  oxide,  and 
ammonia; — ^with  alkaline  chromates  mixed  with  acetic  acid,  into  water, 
sulphur,  and  chromic  oxide;  and  with  the  aid  of  heat,  sulphuric  acid  also. 
(See  these  acids.)^-<^.  In  contact  with  hydrosulphuric  acid  at  ordinary  tem- 
peratures, many  metallic  oxides,  eyen  when  combined  with  acids,  are 
resolved  by  double  decomposition  into  water  and  metallic  sulphides; 
with  others,  the  change  does  not  take  place  till  heat  is  applied  {Seh.  41, 
42,  43,  44).  Ferric  oxide  dissolved  in  acids  is  reduced  to  ferrous  oxide, 
with  formation  of  water  and  precipitation  of  sulphur, — and  sometimes, 
if  the  liquid  be  heated,  with  formation  of  sulphuric  acid. 

5.  With  one  atom  of  iodine,  bromine,  or  chlorine,  hydrosulphurie 
acid  yields  hydriodic^  hydrobromic,  or  hydrochloric  acid  gas,  and  sulphur ; 
the  latter  may,  by  an  excess  of  these  bodies,  be  converted  into  iodide, 
bromide^  or  chloride  of  sulphur.  If  water  be  likewise  present,  iodine 
in  excess  produces  sulphuric  acid,  provided  the  temperature  be  raised 
(H.  Rose,  Pogg,  47>  161);  but  chlorine  produces  that  acid  abundantly. 
Terchloride  of  phosphorus  and  hydrosulphuric  acid  produce  hydrochlone 
acid  and  tersulphide  of  phosphorus.  (SeruUas.) 

6.  Heated  potassium  or  sodium  absorbs  the  whole  of  the  sulphur 
and  one  volume  of  hydrogen  from  SI  yolnines  of  hydrosulphurio  acid  gas, 
leaving  1  volume  of  hydrogen  unabsorbed: 

K  +  2HS  =  KS,  HS  +  H. 

Tin  heated  in  this  gas  forms  sulphide  of  tin,  and  leaves  pure  hydrogen 
gas,  of  the  same  volume  as  the  original.  (Gay-Lussac  A  Th^nard.) 

ComMncUions.  a.  With  Water: — «.  HydiAieqfffydrogidphuricaeid. 
1.  When  persulphide  of  hydrogen  enclosed  in  a  sealed  tube,  and  perhaps 
a  little  moist,  has  resolved  itself  into  sulphur  and  liquid  hydrosulphurio 
acid  (II.  197),  there  are  formed,  after  a  time,  a  few  transparent  and  colour- 
less crystals,  which,  on  opening  the  tube,  immediately  liquify,  and  then 
disappear  with  violent  evolution  of  gas. — 2.  When  hydrosulphuric  acid 
gas  is  passed,  at  a  temperature  of — 18°  (0''  F.)  through  alcohol,  which  is 
mixed  with  such  a  quantity  of  water,  that  the  water  does  not  freeee  at 
*^18^  (or  through  acetic  ether),  crystals  are  produced  resembling  ice,  and 
apparently  of  an  octohedral  form.  As  soon  as  the  vessel  is  taken  out  of 
the  freezing  mixture,  these  crystals  disappear  with  brisk  effervescence : 
enclosed  in  a  sealed  tube,  they  disappear  at  ordinary  temperatures,  but 


200  SULPHUR, 

reappear  every  time  the  tube  is  cooled  down  to  — 18^  (WdUer,  Ann, 
Pharm.  33, 125.) 

fi  Aqueous  sohUum  of  Hydrosulphuric  acid,  ffydrotulphuric  acid  water. 
Sulphuretted  Hydrogen  Water,  Water  at  ordinary  temperatures  absorbs 
its  own  volume  of  hjdrosulphuric  acid  gas,  according  to  Henry  &  Dalton; 
at  18°  (0°  F.),  according  to  Th.  Saussure,  2^  times  its  volume;  and  at  11** 
(52"*  P.)  according  to  Gay-Lussac  &  Thenard,  3  times  its  volume.  To 
prepare  this  solution,  the  gas  previously  washed  with  water  {App.  43)  is 
passed  alternately  through  each  of  two  bottles  half-filled  with  water: 
while  it  is  being  passed  through  one,  the  other  is  closed  with  the  stopper 
and  shaken,  to  ensure  complete  absorption ;  and  thus  the  process  is  con- 
tinued till  the  water  is  completely  saturated.  One  of  the  bottles  is  then, 
completely  filled  with  the  liquid,  and  removed  with  the  mouth  downwards. 
— Colourless  liquid,  having  the  odour  of  putrid  eggs,  sweetish  and  faint. 
When  heated,  it  evolves  the  whole  of  the  gas.  Sulphur  is  precipitated 
from  this  liquid  by  the  oxygen  of  the  air,  by  that  of  peroxide  of  hydrogen^ 
sulphurous,  selenious,  iodic,  bromic,  hyponitric,  and  nitric  acid,  also  by 
iodine,  bromine,  and  chlorine, — ^the  hydrogen  of  the  hydrosulphuric  acid 
combining  with  the  oxygen,  iodine,  bromine,  or  chlorine.  The  air  pre- 
cipitates the  sulphur  slowly,  in  the  form  of  milk  of  sulphur :  according  to 
Vauquelin  (J,  Pharm,  11,  126),  a  small  quantity  of  sulphuric  acid  may 
be  produced  at  the  same  time.  Peroxide  of  hydrogen  does  not  render 
sulphuretted  hydrogen  water  milky  in  less  than  a  ouartor  of  an  hour. 
(Thenard.)  Sulphurous  acid  likewise  precipitates  sulphur  slowly :  sele- 
nious acid  produces  an  immediate  precipitate  of  selenide  of  sulphur. 
Iodine  in  excess  produces  sulphuric  acid,  but  only  when  heat  is  applied ; 
chlorine  produces  it  at  ordinary  temperatures.  Mercury  shaken  up  with 
sulphuretted  hydrogen  water  does  not  abstract  the  whole  of  the  sulphur, 
even  in  the  course  of  several  months.  (0.  Henry, «/".  Pharm.  9,  486.)  If 
the  liquid  be  left  in  contact  with  air  and  metal  at  the  same  time,  the 
metal  quickly  abstracts  the  sulphur,  while  the  hydrogen  combines  with 
the  oxygen  of  the  air.  Sulphuretted  hydrogen  water  kept  for  three 
quarters  of  a  year  in  a  bottle  containing  air  was  found  to  contain  sulphate 
of  ammonia.  (Herzog.  N.  Br.  Arch,  3,  167.) 

h.  With  several  Salifiable  Bases.  HydrotulphaJtes.  (Vid.  Metallic 
Sulphides.)-^.  With  Bisulphide  of  Carbon. — d.  With  Metallic  Sulphides. 
— €,  With  Cyanogen^  Hydrosulphocyanio  acid,  Alcohol^  Volatile  and 
Fixed  Oils. 

Sulphur  and  Carbon. 
A.    Bisulphide  of  Carbon.    CS*. 

Schwefel-hohlenstoff,  Schvfefelralcohol,  Carhure  de  soufre,  Percarhure  de 
sou/re,  Sou/re  carhuri  liquide,  Acide  sulfocarhonique  of  Couerbe  ;— • 
improperly:  Liquid  Sulphuretted  Hydrogen,  Fliimger  Wasserstof^ 
schwefel,  Sou/re  hydrogSn^  liquide. 

Formation,  When  sulphur  is  brought  in  contact  with  carbon  at  a 
red  heat;  when  sulpho-cyanogen  is  heated;  and  when  wax,  sugar,  resin, 
and  other  organic  substances  are  heated  with  sulphur.  From  a  mixture 
of  sulphur  and  charcoal -powder,  the  sulphur  volatilizes  before  the  charcoal 
has  obtained  the  temperature  required  to  induce  combination.  (Clement  Sc 
Desormes.) 


BISULPHIDE  OF  CARBON.  201 

Preparation,  1.  By  passing  sulphur  vapour  over  ignited  charcoal* 
The  charcoal  must  be  freed  as  completely  as  possible  from  water  and  hy- 
drogen by  i^ition,  because  those  substances  would  convert  the  finit 
portions  of  sulphur  into  hydrosulphuric  acid.  It  is  used  in  small  pieces, 
or  in  very  coarse  powder:  in  the  state  of  fine  powder,  it  would  not  give 
free  passage  to  the  sulphur.-^<i.  A  porcelain  tube  filled  with  charcoal  ia 
connected  at  one  end  with  a  receiver,  and  at  the  other  with  a  glass  tube 
containing  pieces  of  sulphur,  and  closed  by  a  stopper  through  which  a  wire 
passes.  As  soon  as  the  porcelain  tube  is  red  hot  and  the  charcoal  haa 
ceased  to  evolve  cas,  the  pieces  of  sulphur  are  gradually  pushed,  one  after 
the  other,  into  the  tube.  (Clement  &  D^sormes.) — 6.  A  cast-iron  tube 
(water-pipe),  5  feet  long  and  1^  inch  wide,  is  filled  with  charcoal  from  b 
to  c  (App,  46)  and  surrounded  with  fire ;  into  the  upper  end  of  this,  a 
small  iron  tube  a  is  luted  with  a  mixture  of  moist  clay  and  a  small  quan- 
tity of  iron  filings,  sulphur,  and  sal  ammoniac.  Through  this  tube  the 
sticks  of  sulphur  are  pushed  at  regular  intervals,  by  means  of  a  rod,  into 
the  tube  b,  and  the  tuoe  a  is  closed  with  a  stopper.  Another  smaller  tube 
d  IB  attached  to  the  lower  end  of  the  large  tube,  and  connected  by  means 
of  the  funnel  e  with  the  tubulated  receiver  //  and  this  receiver  is  con- 
nected by  a  bent  tube  with  a  well  cooled  Woulfe's  bottle  g.  Since  part 
of  the  sulphur  passes  through  without  combining  with  the  carbon,  the 
neck  of  the  funnel  and  that  of  the  receiver  must  be  very  wide,  or  they  will 
be  stopped  up  bv  the  sulphur.  If  the  process  be  long  continued,  fresh 
pieces  of  charcoal  must  be  introduced  from  time  to  time  through  the  tube  a« 
By  this  process,  two  or  more  pounds  of  the  compound  may  be  obtained 
in  the  course  of  the  day.  The  tube  lasts  a  long  time,  in  fact  till  it  is  com- 
pletely corroded  by  the  formation  of  sulphide  of  iron.  (Gm.) — c.  Two 
black-lead  crucibles,  each  of  the  capacity  of  3  oz.,are  ground  at  the  edges^ 
to  make  them  fit  each  other  well,  and  then  luted  together.  (App.  48.) 
The  vessel  thus  formed  is  filled  with  pieces  of  charcou  of  the  size  of  hau 
a  cubic  inch,  and  placed  in  an  air-furnace  having  a  good  draught.  A  glass 
tube  a  furnished  with  a  stopper  passes  through  the  bottom  of  the  upper 
crucible,  and  reaches  nearly  to  the  bottom  of  the  lower  one.  To  protect 
the  upper  end  of  the  tube,  by  which  the  sulphur  is  introduced,  from  the 
heat,  the  iron  plate  k  kis  fixed  upon  the  upper  crucible,  as  represented  in 
the  figure.  A  curved  earthen  tube  c,  an  inch  wide,  is  luted  into  an  aper- 
ture in  the  side  of  the  upper  crucible  near  the  top,  and  serves  to  convey 
the  vapours  through  the  glass  tube-funnel  d,  3  feet  long,  into  the  Woulfe  a 
bottle  e.  This  bottle  contains  a  little  water,  which  must  not,  however, 
exert  any  pressure.  A  stick  of  sulphur  an  inch  long  is  pushed  in  every 
minute  [1] ;  and  in  two  hours,  from  12  to  14  ounces  of  bisulphide  of  carbon 
are  obtained,  (Brunner,  Pogg,  17,  484.) — d.  A  porcelain  tube  a  is 
luted  into  the  tubulure  of  a  coated  earthen  retort  b  {App,  47),  so  as  to 
reach  within  an  inch  and  a  half  of  the  bottom.  The  retort  is  filled  by  the 
neck  with  pieces  of  charcoal  of  the  size  of  hazel-nuts,  and  placed  in  the 
air-furnace  in  a  slightly  inclined  position,  so  that  the  porcelain  tube  may 
be  a  little  on  one  side,  and  the  furnace  covered  on  that  side  with  a  tile. 
The  neck  of  the  retort  is  connected  by  the  bent  tube-funnel  e  with  the 
two  bottles  d  and  e.  In  a  few  hours,  upwards  of  a  pound  of  sulphide  of 
carbon  is  obtained.  (Pleischl,  ZeiUchr,  Phys,  v.  W,  3,  97.) — e,  A  coated, 
cylindrical,  earthenware  bottle  6,  10  inches  wide  and  24  inches  high,  is 
filled  with  pieces  of  charcoal  of  the  size  of  a  cubic  inch,  and  placed  directly 
on  the  grate  of  the  air-furnace,  a  fire-space  5  inches  wide  being  left 
between  the  bottle  and  the  walls  of  the  tomace.    A  tube  a,  fitting  into 


209  SULPHUR. 

the  Bide  of  the  bottle  at  its  lower  part,  passes  upwards  from  the  famace 
in  a  slanling  direetion,  and  throngh  this  the  sulphur  is  introduced.  Orer 
the  upper  opening  of  the  bottle  is  luted  an  earthenware  head  c,  having  a 
long  beak,  2  inches  wide.  By  this  the  rapours  are  conducted  through  a 
refrigerating  tube  d,  of  iron  plate,  4  feet  long  and  4  inches  wide,  into  the 
receirer  /,  also  made  of  iron  pUite.  This  receirer  is  surrounded  by  an 
outer  cylinder  e  filled  with  ice.  From  it  the  sulphide  of  (»rbon  flows 
through  the  tube  h,  fitted  into  the  bottom  and  dipping  into  a  bottle  com- 
pletely filled  with  water.  The  upper  opening  ^,  which  is  large  enough  to 
admit  the  hand,  is  left  constantly  open,  so  that  the  vapour  may  not  escape 
through  the  pores  of  the  bottle.  For  the  first  two  hours,  the  heat  is 
cautiously  applied;  but  after  that,  the  bottle  is  kept  constantly  at  a  strong 
red  heat.  A  pound,  or  a  pound  and  a  half  of  sulphur  is  introduced  through 
a  every  quarter  of  an  hour.  About  an  hour  after  the  first  introduction  of 
the  sulphur,  the  sulphide  of  carbon  begins  to  come  oyer,  and  soon  flows  in 
a  continuous  stream.  Fifty  pounds  of  sulphur  yield,  in  12  or  14  hours, 
^m  38  to  40  lbs.  of  bistilphide  of  carbon ;  part  of  that  which  is  produced 
is  lost  by  escaping  through  the  pores  of  the  bottle.  (Schrotter,  Anit, 
Pharm.  39,  297.)  This  excellent  method  deserves  to  be  tried  with  a 
bottle  and  head  of  oast-iron. — /.  An  aperture  having  been  made  in  the 
side  of  a  wrought-iron  quicksilver  bottle,  towards  the  upper  part,  a  curved 
copper  tube  is  adapted  to  it,  to  conduct  the  vapour  into  a  Woulfe's  bottle 
surrounded  with  ice;  and  a  straight  tube,  also  of  copper,  is  fitted  into  the 
middle  opening  of  the  bottle  for  the  purpose  of  introducing  the  sulphur. 
(Mulder,/.  Pharm.  23,  22;  also/;  pr.  Cfum,  13,  444.)  This  form  of 
apparatus  is  not  to  be  recommended,  inasmuch  as  copper  and  wrought-iron 
are  quickly  corroded  by  sulphur.  Wittstein  {Repert,  66,  62)  obtained 
onl^  a  few  ounces  of  sulphide  of  carbon  from  1  ^  lb.  of  sulphur  in  7  hours, 
while  the  metal  of  the  bottle  and  tubes  was  converted  into  sulphide. 

2.  Charcoal  is  heated  in  an  earthenware  or  porcelain  retort  fitted  with 
tube-funnel  and  receiver,  in  contact  with  metallic  sulphides  which  give  up 
their  sulphur  with  tolerable  facility :  f.  g,,  4  parts  of  iron  or  copper  pyrites 
pounded  and  mixed  with  1  part  of  charcoal;  or  bituminous  wood  penetrated 
with  sulphur  pyrites.  ^Lampadius.)  Tersulphide  of  antimony  with  char- 
coal requires  a  strong  neat,  and  pelds  but  a  scanty  product.  (Clement  & 
D^sormes.)  But  10  parts  of  tersulphide  of  antimony  with  1  pEirt  sulphur 
and  3  parts  charcoal  yields — besides  \  pt.  brown  sulphide  of  antimony, 
which  collects  on  the  surface  of  the  water  in  the  receiver — a  brown  distil- 
late, which,  when  rectified,  yields  If  pt.  bisulphide  of  carbon.  The 
residue  in  the  retort  may  be  mited  with  fresh  sulphur  and  charcoal,  and 
used  again.  (Lampadius,  J,pr.  Ohem,  4,  451.) 

Purijleation.  Bisulphide  of  carbon  prepared  by  either  of  the  methods 
aboye  described  contains  excess  of  sulphur  in  solution,  from  which  it  may 
be  freed  by  distillation  in  a  glass  retort  oyer  the  water^bath.  When  the 
distillation  is  conducted  slowly,  the  residual  sulphur  forms  beautiful  crys- 
tals. Any  water  which  adheres  to  the  liquid  may  be  removed  by  distilla- 
tion from  chloride  of  calcium.  Hydrosulphuric  acid  may  be  got  rid  of  by 
agitation  with  white  lead. 

Properties.  Transparent  and  colourless;  yery  fluid.  Bpecific  grayity 
1-300  rLampadius);  1272  (Berzelius  &  Marcet) ;  1-263  (Clusel);  1265 
(Couerbe).  Of  strong  refracting  power.  Does  not  solidify  at  —52*. 
Boilint  point,  from  40-5«  to  45-5°  (Berzelins  &  Marcet);  45^  (Couerbe); 
46-6*'  (Qay-Lussac).    Tension,  density,  refractive  power,  and  latent  heat 


'} 


BISULPHIDl  OF  CARBON.  80S 

of  th«  taponr  (I.,  2685  279^  96  atid  288.)  Wh^  thliS  liquid  erftporated 
in  tlie  air,  and  still  more  in  raciio,  rapid  absorption  of  heat  takes  place. 
(I.,  272.)  Odour^  unpleasantly  aromatic;  taste  cooling,  bat  at  the  same 
time  intensely  sharp  and  aromatic.  Very  inflammable.  Insoluble  in 
water. 

Beifholl.  Th^nard 
CalculatioiL  &  Vaaq.         Ben.  ft  MaK.  Coaerbe. 

C    6  15-79  14-5  1517  16*205 

2S    32  84-21  85-5  84-83  83*795 

CS» 38  100-00  100-0  100-00  lOO'OOO 

Vol.  6p.  gr. 

Carbon  vapour 1  0*4160 

Sulphur  Tapoor     2  2*2185 


Vapour  of  CS«      1  2*6345 

(CS«  «=  76-44  +  2  .  201-17  =  478-78.    BerteUos.) 

Closel  thought  that  he  had  found  in  100  parts  of  bisulphide  of  carbon^ 
28*49  carbon,  5867  sulphur,  6*98  nitrogen,  and  5-86  hydrogen. 

Decampositioru,  1.  Bisulphide  of  carbon  takes  fire  in  the  air  at  860°, 
according  to  Berzelius  &  Marcet;  uilder  100'',  according  to  Lampadins 
(/.  pr,  Uhem.  4, 891)  j  and  bums  with  a  blue— or,  according  to  Vauquelin 
&  Robiqnet,  with  a  white  and  purple  red  flame.     Its  combustion  in  oxy-* 

Sn  gas  deyelopes  heat  sufficient  to  melt  platinum  wire.  (Berselins  8c 
arcet.)  Its  vapour  mixed  with  oxygen  gas  and  inflamed  in  Volta's 
eudiometer  by  the  electric  spark,  produces  a  most  riolent  explosion :  a 
drop  of  it  eraporated  in  6  cubic  inches  of  air  in  the  air-pistol,  produces, 
according  to  Bbttger  (J,  pr.  Chem,  12,  868),  a  sharp  detonation  when 
inflamed.  The  products  of  the  combustion  are  always  sulphurous  and 
carbonic  acid  {Sch.  26),  or  carbonic  oxidoi  if  the  supply  of  oxygen  is  too 
small  to  form  carbonic  acid.  (Berzelius  &  Marcet.)  According  to  Cluseli 
water  and  nitrogen  gas  are  likewise  produced. 

2.  Gold  oil  of  ritriol  decomposes  bisulphide  of  carbon  into  sulphur  and 
carbon,  the  latter  of  which  blackens  the  lower  stratum  of  the  oil  of  ritriol. 
The  rapours  of  these  two  substances  passed  simultaneously  throngh  a  red* 
hot  porcelain  tube  yield  carbonic  oxide  (no  carbonic  acid),  sulphurous 
acid,  hydrosulphurio  acid,  and  sulphur.  (Brault  &  Posgiale,  J.  Pharm. 
2 1 , 1 87.)  Vapour  of  bisulph  ide  of  carbon  detonates  with  hypochlorous  acid 
gas,  forming  carbonic  acid,  sulphuric  acid,  chloride  of  sulphur,  and  chlo* 
rine;  with  solution  of  hypochlorous  acid,  it  yields  carbonic,  sulphuric,  and 
hydrochloric  acid,  together  with  free  chlorine.  (Balard.) 

IT  When  rapour  of  bisulphide  of  carbon  and  dry  chlorine  gas  are 
passed  together  through  a  red-hot  porcelain  tube  filled  with  fragments  of 
porcelain,  and  thence  into  a  receiyer  surrounded  by  a  freezing  mixture, 
a  yellowish-red  liquid  is  obtained,  which  is  a  mixture  of  chloride  of  sul^ 
phur  and  perchlonde  of  carbon  (C*Cl^).  When  a  few  grammes  of  bisul-< 
phide  of  carbon  are  placed  in  a  yessel  of  dry  chlorine  gas,  and  left  for 
some  days  or  weeks  at  the  ordinary  temperature  of  the  air,  a  dark  yellow 
liquid  is  produced,  consisting  of  chloride  of  sulphur,  together  with  a  com* 
pound  of  chlorine,  sulphur  and  carbon,  whose  composition  is  represented 
by  the  formuhi  CSCl :  it  may  be  regarded  as  Phosgene  (GOCl),  in  which 
the  atom  of  oxygen  is  replaced  by  an  atom  of  sulphur.  (Kolbe,  Ann, 
PAam.45,  41.)ir 

d.  When  vapour  of  bisulphide  of  carbon  is  passed  over  ferric,  man- 
gftfii^  or  ttannio  oxide  kept  at  a  red  heat  in  a  glass  tube,  the  products  are 


204  SULPHUR. 

a  metallic  sulphide,  together  with  carbonic  and  sulphurous  acid  gas,  and 
without  a  trace  of  water.  (Berzelius  &  Marcet.) 

3SnO«  +  2CS«  =  3SnS  +  2C0«  +  S0«. 

On  passing  the  vapour  over  Ignited  baryta,  strontia,  or  lime,  there  is 
formed — with  ignition  in  the  case  of  lime — &  mixture  of  2  atoms  of  sul- 
phide with  1  of  carbonate.  (Berzelius,  Sch,  59.) 

3BaO  +  CS«  =  2BaS  +  BaO,  C0«. 

On  the  other  hand,  when  yapour  of  bisulphide  of  carbon  is  passed  over 
gently  ignited  carbonate  of  potassa,  carbonic  acid  is  evolyed,  and  there 
remams  a  brownish-black  fused  mixture  of  1  atom  of  tersulphide  of  potas- 
sium and  1  atom  of  charcoal.  (Berzelius,  Sck,  62.) 

2(KO,CO«)  +  3CS«  =  3C0«  +  2KS=»  +  2C. 

Possibly,  the  20  is  at  first  combined  with  the  2KS' ;  but  on  digestion  with 
water,  it  remains  undissolyed. 

BecquereFs  account  of  the  decomposition  of  nitrate  of  copper  covered 
with  bisulphide  of  carbon  (L,  400)  requires,  according  to  Wbhler  {Pogg. 
17,  482),  the  following  corrections :  (1.)  The  black  substance  is  not  char- 
eosJ,  but  sulphide  of  copper,  formed  irom  the  excess  of  sulphur  dissolved 
in  the  sulphide  of  carbon ;  hence  it  is  produced  without  the  addition  of 
nitrate  of  copper.  (2.)  The  copper  is  quickly  converted  into  non-crystal- 
line sulphide  of  copper,  if  the  sulphide  of  carbon  is  merely  covered  with 
very  dilute  nitric  acid. 

4.  Heated  potassium  takes  fire  in  vapour  of  sulphide  of  carbon,  bums 
with  a  reddish  flame,  and  becomes  covered  with  a  blackish  crust.  This 
substance  dissolves  in  water,  with  separation  of  charcoal,  producing  a 
black  carbonaceous  liquid.  (Berzelius.) — 5.  Bisulphide  of  carbon  passed 
in  the  state  of  vapour  over  a  quantity  of  red-hot  iron  or  copper  not  suffi- 
cient to  decompose  it  completely,  is  converted  into  a  very  thin,  rose- 
coloured  liquid  having  a  sharp  taste.  This  liquid  probably  contains  mono- 
sulphide  of  carbon  (OS),  together  with  undecomposed  bisulphide.  The  cop- 
per is  converted  into  sulphide,  and,  according  to  Cluzel  (BerthoUet,  Th^nard 
&  Vauquelin  assert  the  contrary),  covered  with  a  carbonaceous  substance. 

6.  Bisulphide  of  carbon,  kept  for  a  long  time  under  water  in  vessels 
containing  air,  acquires  a  yellow  colour,  and  is  partially  converted  by 
oxidation  into  carbonic  and  sulphuric  acid.  (Berzelius.)  When  water  is 
heattfd  with  bisulphide  of  carbon  in  a  sealed  glass  tube,  the  heat  being  con- 
tinually increased,  it  first  becomes  milky,  and  afterwards  clear,  the  colour 
being  greenish  at  the  beffinniug,  but  gradually  becoming  darker,  and  at 
last  nearly  black.  The  bisulphide  of  carbon  rises  to  the  top  of  the  water 
and  then  passes  to  the  state  of  vapour.  On  cooling,  the  green  colour  of 
the  water  passes  into  yellowish,  and  the  bisulphide  of  carbon  again  sinks 
to  the  bottom.  If  the  water  contains  chlorate  of  potassa,  it  assumes  a 
lemon-yellow  colour  when  heated  rather  strongly  in  contact  with  the  sul- 
phide of  carbon— effervesces — and  deposits  a  drop  of  an  oily  liquid,  which 
disappears  on  the  application  of  a  stronger  heat,  melted  sulphur  being 
separated  at  the  same  time.  On  cooling,  the  bisulphide  of  carbon  is  found 
to  be  decomposed,  and  the  chlorate  of  potassa  no  longer  crystallizes  out. 
When  the  tube  is  opened,  gas  (carbonic  acid  t)  escapes  with  a  strong  explo- 
sion, •  and  the  water  exhibits  a  strongly  acid  reaction.  (Oagniara  de  la 
Tour,  Ann,  Chem,  Phy$,  23,  267.) 

7.  Bisulphide  of  carbon  dissolves  gradually  in  aqueous  solutions  of  the 
fixed  alkalis,  and  forms  a  brown  solution  containing  an  alkaline  carbo* 


^       SULPHUR  AND  CARBON.  205 

nate  and  a  oompound  of  bisulphide  of  carbon  with  a  metallic  sulphide 
(Berzellns)^ 

3KO  +  3CS"  =  KO,  C0«  +  2  (KS,  CS*) 

or  an  alkaline  carbonate  and  an  alkaline  hydrosulpho  carbonate, 
3K0  +  2CS«  +  2H0  «  KO,  C0«  +  2  (KO  +  HCS»). 

8.  Bisulphide  of  carbon  placed  for  a  long  time  in  contact  with  solu- 
tion of  ammonia,  forms  a  dark,  brown-red  liquid  containing  hydrosulpho- 
carbonate  and  hydrosulphocjanate,  but  no  carbonate  of  ammonia  (Zeise, 
Schw.  41,  171),  probably  in  this  way: 

4NH*  +  4CS«  =*  2(NH*,  HCS»)  +  NH',  HC«NS». 

9.  Bisulphide  of  carbon  dissolves  yerj  abundantly  in  alcohol  saturated 
with  ammoniacal  gas.  The  solution  remains  alkaline,  even  with  a  large 
excess  of  sulphide  of  carbon.  Even  when  protected  from  the  air  it  soon 
turns  yellow,  then  brown,  and  smells  of  hydrosulphuric  acid.  After  the 
lapse  of  from  10  to  30  minutes,  it  deposits  yellow  feathery  crystals  of 
hydrosulphocarbonate  of  ammonia;  then  more  shining  crystals  of  hydro- 
sulphocyanate  of  ammonia  are  formed,  while  those  of  the  hydrosulpho- 
caroonate  diminish  in  quantity.  The  alcoholic  liquid  still  retains  very 
large  quantities  of  hydrosulphocyanate  and  hydrosulphate  of  ammonia, 
which,  on  distillation  or  exposure  to  the  air,  are  resolved  into  hydrosulphate 
of  ammonia,  which  escapes,  sulphur  which  crystallizes  out,  and  sulpho- 
cyanate  of  ammonia  which  remains  in  solution.  (Zeise.)  In  the  first 
instance,  probably,  3  atoms  of  ammonia  and  3  atoms  of  bisulphide  of  car- 
bon resolve  themselves  into  1  atom  of  hydrosulphocarbonate  and  1  atom 
of  hydrosulphocyanate  of  ammonia : 

3NH'  +  3CS«  =  NHS  HCS»  +  NH',  HC'NS*,  HS. 
The  subsequent  diminution  of  the  hydrosulphocarbonate  and  increase  of 
the  hydrosulphocyanate,  with  formation  of  hydrosulphate  of  ammonia 
probably  arises  from  the  resolution  of  2  atoms  of  hydrosulphocarbonic  acid 
and  1  atom  of  ammonia  into  3  atoms  of  hydrosulphuric  acid  and  1  atom 
of  hydrosulphocyanic  acid.  (Zeise.) 

NH»  +  2HCS»  =  3HS  +  HC«NS>,  HS. 

[For  the  formation  of  xanthonate  of  potassa  from  bisulphide  of  carbon, 
potash,  and  alcohol,  vid.  Xanthome  acid,^ 

Combinations,  a.  Miscible  in  all  proportions  with  liquid  carbonic 
acid.— i.  With  phosphorus. — c.  With  sulphur. — rf.  With  hydrosulphuric 
acid. — e.  With  iodine.—/.  With  bromine. — g.  With  chloride  of  sulphur. 
— h.  With  chloride  of  nitrogen. — i.  With  ammonia. — h  With  metals, 
€,  g.  copper? — L  With  metallic  sulphides,  (q.  v.).— w.  With  alcohol^ 
ether,  volatile  and  fixed  oils,  camphor,  and  resins. 

B.  Sulphuretted  Bisulphide  of  Carbon. — Bisulphide  of  carbon 
may  be  made  to  combine,  by  solution,  with  an  additional  quantity  of 
sulphur,  whereby  it  acquires  a  yellowish  colour.  When  the  liquid  is 
distilled,  or  when  it  evaporates  or  bums  in  the  air,  this  excess  of  sulphur 
remains  behind ;  it  likewise  crystallizes  very  beautifully  from  a  solution 
formed  at  a  higher  temperature.  The  excess  of  sulphur  is  likewise 
precipitated  on  mixing  the  liquid  with  ether,  alcohol,  or  a  hot  solution  of 
caustic  potash.  Amalgam  of  lead  or  silver  agitated  with  it  idso  removes 
the  sulphur^  forming  ralphide  of  lead  or  sulphide  of  silver.  (Berzelius.) 


206  8ULPHUE. 

G.  BvtTjansrm  Chabooal. — Cbaieodi  which  has  beeu  used  io 
the  preparation  of  bisulphide  of  carbon  (method  1)  contains  a  quantity 
of  sulphur  80  intimately  united,  that  it  cannot  be  removed  by  ignition : 
sulphate  of  potassa  is  however  obtained  when  the  charcoal  is  deflagrated 
with  nitre.  (Clement  &  D^sormes.)  The  same  substance  is  obtained 
by  washing  gnnpowder  with  water  to  remove  the  nitre,  and  then  heating 
it  stronglv  to  drive  off  sulphur.  (Proust.)  According  to  Berzeliuf,  this 
oompound  should  be  regarded  as  a  iStipercarburet  ofStUphur. 


D.      HTBBOSVLPHO-CABBOlflO  AciD.      HCS'. 

Sed  Acid,  XothsHure^  8Hure  det  rathwerdenden  Salzes,  Bydreihuhcarbon" 
Bdure  (Zeise);  Eohlenichwefelwasserstofiaure,  (Berzelins.) 

FarmaUan.  1.  (11.  204,  7.)  2.  Aeneous  solutions  of  alkaline  hydro- 
sulphates  or  monosulphides  of  tne  alkali-metals  rapidly  dissolve  bisulphide 
of  carbon,  forming  a  brown  solution  of  an  alkaline  hydrosnlphoearbonate, 
or  of  a  oompound  of  bisulphide  of  carbon  with  a  metallio  sulphide. 
(Berzelius.) 

Preparation.  Hydrosulphocarbonate  of  ammonia,  dried  and  pressed,  is 
put  into  slightly  dunted  hydrochloric  acid;  more  water  is  then  quickly 
added,  and  the  supernatant  watery  liquid  decanted  off  from  the  oily  acid 
as  it  settles  down.  If  the  quantity  of  hydrochloric  acid  is  too  great,  the 
oily  matter  redissolves,  and  if  the  hydrochloric  acid  is  too  concentrated, 
sulphuretted  hydrogen  is  evolved.  (Zeise.) 

Properties,  Red-brown,  transparent,  oily  liquid,  heavier  than  water; 
has  an  odour  like  that  of  hydrosulphuric  acid,  but  at  the  same  time  cha- 
racteristic. Gives  a  red  precipitate  with  lead  salts,  red-brown  with 
cnpric,  salts  and  yellowish  with  mercuric  salts.  All  these  precipitates  turn 
black  in  a  few  hours.  (Zeise.) 

Ztaae's  Calculation.  Or: 

H  1  1-82  C8« 88  6909 

C    6  10-91  HS  17  30-91 

3S   48  87-27 

HCS» 55  lOOMW  C»,  H8  ....  55  100-00 

(CS«  -f-  HS  «  478*78  +  213*65  »  692-43.    BeneUas.) 

Combinations,  a.  This  acid  dissolves  in  aquooos  hydrochloric  or  sol- 
phurio  acid. 

h.  It  combines  with  salifiable  bases,  forming  aalUi  called  ffydrosulpho- 
carbonates  (vid.  Metallic  Sulphides). 


SutPHUB  AND  BOBOK. 

A.  BuLPHiBB  OF  BoBOK.-^Boron  heated  to  redness  in  sulphur  rapoiir 
takes  fire  and  burns,  producing  sulphide  of  boron,  which  forms  a  white, 
opaque  deposit  on  the  sides  of  the  vessel,  but  appears  ffrey  at  the  bottom, 
from  beiuff  mixed  with  uncombined  boron.  Sulphide  of  boron  deeomposeo 
water  with  violence,  sulphuretted  hydrogen  being  evolved,  mekI  boiaeie 


SULPHUR  AND  PHOSPHORUS.  307 

aoid  remaining  in  solution.  On  treating  the  grey  sulphide  of  horon  ahove 
mentioned  with  vater,  the  pure  boron  mixed  with  it  falls  to  the  bottom. 
If  the  boron  be  merely  heated  in  the  sulphur  vapour  till  it  takes  fire,  and 
no  stronger  heat  be  afterwards  applied,  a  sulphide  of  boron  containing 
excess  of  sulphur  is  formed;  and  this,  when  digested  in  water,  deposits 
the  excess  of  sulphur  in  the  form  of  milk  of  sulphur.  (Berielius,  Fogg.  3, 
145.^  When  sulphur  is  melted  with  boron,  an  olive^ooloured  mixture  ia 
obtamed,  from  which,  according  to  Berselins,  the  sulphur  may  be  separated 
by  distillation. 

B,  SuLPHATB  OF  BoRON  %  Boron  dissolves  in  hot  oil  of  vitriol  with 
slight  effervescence,  forming  a  black  liquid,  which  gives  a  blaok  precipitate 
with  potash.  (H.  Davy.) 

C.  SuLPHATB  OF  BoRACio  AciD.  Boraoic  acid,  whether  anhydrous  or 
crystallized,  dissolves  in  oil  of  vitriol  in  large  quantity,  especialljr  at  an 
elevated  temperature,  forming  a  colourless  compound  of  the  consistence 
of  turpentine :  part  of  the  boracio  aoid  separates  from  it  spontaneously. 
(Gm.) 

Sulphur  and  Phosphorus. 
A.  SuLPHiDBS  OF  Phosphorus. 

Sulphur  and  phosphorus  unite  in  all  proportions,  and  with  vivid  com- 
bustion and  powerful  detonation.  Small  quantities  of  phosphorus  and 
sulphur,  both  in  a  state  of  dryness,  heated  together  in  a  glass  tube,  enter 
into  combination,  and  evolve  so  much  heat,  that  the  compound  is  rapidly 
converted  into  vapour,  and  the  tube  bursts  with  a  loud  report.  Explosion 
also  takes  place,  according  to  Pelletier,  when  the  sulphur  and  phosphorus 
are  melted  together  under  water,  especially  if  the  heat  be  too  suddenly 
applied,  and  the  two  bodies  are  about  equal  in  quantity. 

1.  Sulphur  is  added  in  successive  portions  to  phosphorus  kept  in  a 
fused  state  underwater  (Pelletier) ;  or  the  two  bodies  are  rubbed  together 
under  warm  water.  (Level.) — 2.  The  two  substances  are  melted  together 
under  boiling  alcohol  of  80  per  cent.  (R.  B&ttger.) — 3.  Or  under  alcoholic 
solution  of  potash.  (R.  Bdttger.) — 4.  Under  heated  rock-oil.  The  com- 
bination takes  place  without  explosion,  even  with'large  quantities ;  and  the 
rock-oil  is  not  decomposed,  merely  dissolving  a  litUe  of  the  compound ; 
whereas,  oil  of  turpentine  is  decomposed,  and  acquires  an  intolerably  bad 
odour. — 5.  Phosphorus  is  heated  in  an  alcoholic  solution  of  potash  liver 
of  sulphur,  the  liquid  being  agitated,  and  then  left  to  stand  for  some  days. 
The  best  method  is  however  as  follows :  An  alcoholic  solution  of  potash 
is  saturated  at  a  boiling  heat  with  flowers  of  sulphur;  phosphorus  is 
heated  to  fusion  in  the  dark-red  filtrate,  the  liquid  being  carefully  affi- 
tated ;  the  flask  is  left  open  for  several  days  in  a  dark  place,  and  the 
whole  frequently  wanned  and  shaken  up ;  then  after  coolmg,  the  liauid 
sulphide  of  phosphorus  is  several  times  washed  with  water  in  the  dark — 
agitated,  while  still  a  little  turbid^  with  ether — and  kept  under  ether  in  a 
dark  place.  Sulphide  of  phosphorus  obtained  by  this  method  is  a  trans- 
parent liquid,  whereas  that  obtained  by  other  methods  is  mixed  with 
crystals  of  sulphur.  (R.  Bottger.) — 6.  By  decomposing  terchloride  of 
phosphorus  with  hydrosulphuric  acid,  pale  yellow  tersmphide  of  phos- 
phorus is  obtained.  (Semllas.) 


208  SULPHUR. 

3HS  +  PQa  =  3HC1  +  PS«. 

Turbid  sulphide  of  phosphorus  may  be  rendered  transparent  by  agita- 
tion with  aqueous  ammonia  (Faraday),  or  by  pressure  through  chamois 
leather.  (Bock,  Dupr^.) 

Pale  yellow ;  friable  and  semitransparent  when  in  the  solid  stated- 
oily  and  transparent  when  liquid.  Phosphorus  crystallizes  out  from  mix- 
tures containing  excess  of  phosphorus;  and  sulphur  from  those  which 
contain  excess  of  sulphur.  (Faraday,  Mitcherlich,  Bottger.)  According  to 
Dupre,  that  which  crystallizes  out  is  not  sulphur,  but  sulphide  of  phos- 
phorus  with  six  atoms  of  sulphur. 

P*S  (8  pts.  to  1  pt.)  solidifies  at  +  25°.-P«S  (4  pts.  to  1  pt.)  solidi- 
fies at  15°  (Pelletier). 

PS (2  pts.  to  1  pt.)  solidifies  at  -h  10°  (Pelletier),  at  -f  4°  (Faraday); 
according  to  Dupr6,  it  does  not  solidify  till  kept  for  a  long  time  at  —  1 9°, 
and  afterwards  melts  at  -f  5°  or  +  6°;  sp.  gr.  1-80. 

The  compound  of  7  pts.  phosphorus  with  5  pts.  sulphur  is  at  first 
liquid  even  at  —  6*7°,  but  subsequently  deposits  crystals  of  sulphur,  whilst 
PS,  which  solidifies  at  +  4°,  remains.     (Faraday.) 

PS»  (1  pt.  to  1  pt.)  solidifies  at  +  5°  (Pelletier),  melts  at  ll-25*»  Bott- 
ger); remains  liquid  at  —  4®,  but  PS'  crystallizes  out.     (Dnpre.) 

PS'  (2  pts.  to  3  pts.)  remains  liquid  at  — •  4°,  but  contains  crystals  of 
PS«.     (Dupre.) 

PS^  (1  pt.  to  2  pts.)  solidifies  at  +  12*5%  but  is  resolyed  at  the 
same  time  into  a  crysUilline  and  a  liquid  part.  (Pelletier.) 

PS'  (1  pt.  to  3  pts.)  solidifies  at  37*5°,  forming  a  friable  mass.  Melts 
in  boiling  water;  solidifies  on  cooling  to  a  transparent,  lemon-yellow, 
crystalline-grained,  and  tolerably  solid  mass,  which  becomes  doughy  when 
rubbed  at  a  temperature  of  15°.  Crystallizes  on  cooling  from  PS^  and 
still  better  from  PS',  in  pale-yellow  transparent  crystals,  which  must  bo 
dried  between  bibulous  paper  frequently  renewed.  Specific  gravity  202 ; 
begins  to  melt  at  100°,  and  solidifies  to  a  crystalline  mass  on  cooling. 
(Dupre.) 

Sulphide  of  phosphorus  kept  under  ether  quickly  loses  its  transparency 
in  difiiised  daylight,  and  still  more  quickly  in  direct  sunshine,  becoming 
covered  with  a  white  film,  which,  however,  disappears  again  if  the  sub- 
stance be  kept  in  the  dark :  it  does  not  assume  a  red  colour,  either  in 
ether  or  in  water,  as  Bockmann  formerly  observed,  or  yet  in  alcohol. 
(Bottger.)  Sulphide  of  phosphorus  fumes  and  shines  in  the  air;  with  that 
which  consists  of  equal  parts  of  the  two  elements,  this  efiect  takes  place 
at  —  1°.  (Heinrich.)  PS  fumes  less  in  the  air  than  phosphorus,  but  takes 
fire  more  easily:  PS'  fumes  and  shines  less,  and  does  not  take  fire  till 
heated  above  100°;  when  rapid  combustion  takes  place,  sulphurous  and 
phosphoric  acids  are  produced.  (Dupre.) — Nitric  acid  of  1  52  specific 
gravity  placed  in  contact  with  sulphide  of  phosphorus  evolves  nitrous 
acid  fumes  attended  with  violent  hissing,  and  sets  fire  to  the  substance  in 
a  few  minutes ;  nitric  acid  of  1  *2  sp.  gr.  and  likewise  oil  of  vitriol  or  hy- 
drochloric acid,  does  not  act  sensibly  on  it  at  ordinary  temperatures. 
(Bttttger.)  With  solution  of  hypochforous  acid,  sulphide  of  phosphorus 
yields  sulphuric,  phosphoric,  aud  hydrochloric  acids,  and  chlorine. 
(Balard.)  Sprinkled  upon  iodine  at  14°,  it  instantly  takes  fire,  and  burns 
with  a  large  and  tolerably  quiet  flame.  (Bottger.)  Sulphide  of  phos- 
phorus kept  under  water  swells  up  by  degrees ;  evolves  hydrosulphurio 
acid  gas,  which  is  luminous  in  the  dark,  from  the  presence  of  vapour  of 
sulphide  of  phosphorus ;  and  imparts  an  acid  of  phosphorus  to  the  water 


SULPHUR  AND  PHOSPHORUS.  209 

(Pelletier.)  Tersulphide  of  phosphorus  gradually  disappears  nnder  water, 
with  formation  of  hydrosulphuric  and  phosphoric  [jphosphorous]  acids 
(SerullaS;  Ann.  Ckim.  Fhys.  42,  33.)  A  mixture  of  one  part  phosphorus 
and  three  parts  sulphur  does  not  act  upon  water,  except  in  sunshine : 
the  action  is  quicker  between  80**  and  100°;  the  water  becomes  turbid 
and  impregnated  with  hydrosulphuric  acid.  Part  of  the  hydrosulphuric 
acid  produced  appears  to  remain  combined  with  sulphur  in  the  form 
of  persulphide  of  hydrogen,  which  mixes  with  the  sulphide  of  phos- 
phorus, and  renders  it  more  fusible.  This  explains  the  diversity  in 
the  statements  respecting  the  melting  point;  and  the  subsequent  de- 
composition of  the  persulphide  of  hydrogen  accounts  for  the  swel- 
ling up  of  the  sulphide  of  phosphorus.  Solid  sulphide  of  phosphorus 
also  becomes  liquid  on  the  addition  of  persulphide  of  hydrogen ;  it 
likwise  softens  when  a  stream  of  hydrosulphuric  gas  is  directed  upon  it 
under  water :  ammonia  instantly  makes  it  solid  again,  and  at  the  same  time 
ac<^uires  a  yellow  colour.  (Level.)  Bisulphide  of  carbon  in  which  an  equal 
weight  of  sulphide  of  phosphorus  is  immersed,  extracts  the  phosphorus  nrst, 
and  separates  the  greater  part  of  the  sulphur  in  combination  with  a  small 
quantity  of  phosphorus.  Strong  boiling  solution  of  potash  extracts  the 
sulphur  from  the  compound,  leaving  colourless  and  transparent  phosphorus; 
the  latter,  however,  again  takes  up  the  sulphur  from  the  liquid,  when  left 
in  contact  with  it  for  some  time.  (Bottger.)  Sulphide  of  phosphorus 
readily  combines  with  fixed  oils,  producing  phosphorescent  mixtures. 

T  The  sulphides  of  phosphorus  have,  within  the  last  few  years,  been 
more  particularly  examined  by  Berzclius, — from  whose  investigations  it 
appears  that  phosphorus  forms  with  sulphur  a  series  of  compounds  pre- 
cisely analogous  m  composition  to  those  which  it  forms  with  oxygen ; 
that  is  to  say,  to  phosphoric  oxide,  hypophosphorous  acid,  phosphorous 
acid,  and  phosphoric  acid.  Moreover,  some  ot  these  compounds  may  be 
obtained  in  two  isomeric  conditions,  in  one  of  which  the  phosphorus  ap- 
pears to  exist  in  its  ordinary  state,  in  the  other,  in  its  red  modification, 
or  the  state  into  which  it  is  brought  by  the  action  of  light  or  heat. 
{Vid,  p.  108.) 

I.    Bisulphide  of  Phosphorus.    PS. 

ffypo-stdphophosphorous   acidj  Phospliorotis  ffyposulphide,   Hyposuljide 
phosphoreux,  Pliosphormlfuret, 

a.  Ordinary  Modification,  Prepared  by  fusing  together  a  mixture  of 
sulphur  and  phosphorus  in  the  proportion  of  two  atoms  of  phosphorus  to 
one  atom  of  sulphur.  The  materials  may  be  fused  under  boiling  water— 
or  else  in  a  tube  in  which  they  have  been  weighed — ^the  tube  being  first 
sealed  with  the  blow-pipe,  and  then  left  to  itself  till  all  the  oxygen  of  the 
air  which  it  contains  has  combined  with  the  phosphorus.  The  quantity  of 
phosphorus  consumed  by  this  oxidation  is  too  small  to  exert  any  appre- 
ciable influence  on  the  result.  The  temperature  to  which  the  materials 
are  subjected  should  not  exceed  100°;  hence  the  fusion  is  best  performed 
by  the  heat  of  a  water-bath.  The  sulphur  combines  with  the  phosphorus 
at  the  moment  when  the  latter  melts. — 2.  By  digesting  phosphorus  in  an 
alcoholic  solution  of  persulphide  of  potassium  (liver  of  sulphur).  The 
phosphorus  reduces  the  persulphide,  to  a  lower  degree  of  sulphuration,  and 
is  itself  converted  into  disulphide  of  phosphorus  without  taking  an  ad- 
ditional portion  of  sulphur  from  the  excess  of  alkaline  persulphide. 

VOL.    II.  P 


210  SULPHUR. 

Properties.  At  and  abore  0°,  the  disulphide  of  phosphorus  is  a  trans- 
parent, colourless  liquid,  having  the  consistence  of  a  fixed  oiL  At  a  some- 
what lower  temperature  it  solidifies,  forming  a  mass  of  slender,  oolonrless 
crystab.  Fumes  in  the  air,  and  exhales  the  odour  of  phosphorus.  In  an 
atmosphere  free  from  oxygen,  it  may  be  distilled  without  alteration. 
Readihr  takes  fire  in  the  air,  particularly  when  absorbed  by  porous  bodies. 
Insoluble  in  alcohol  and  ether;  but  these  liquids  are  gradually  altered  by 
it,  even  out  of  contact  of  air;  and  the  new  products  dissolye  in  the  liquid, 
while  the  remaining  sulphide  undergoes  no  alteration,  but  merely  diinin- 
ishes  in  yolume.  Oils,  both  fixed  and  yolatile,  dissolve  it  in  small  quantity: 
the  solution  shines  in  the  dark,  and  gives  off  slight  fumes  when  in  con- 
tact with  the  air. 

The  composition  of  disulphide  of  phosphorus  is : — 

Calcnlation.  Benelios. 

2P   62-8  79-69  79*592 

S    16-0  20*31  20-408 

P«SJ 78-8  10000 100000 

(P*S  =  4  .  19614  +  201-17  =  985-73.    BeraeHus.) 

Deeompoiitiofu,  1.  This  compound  may  be  preserved  without  altera- 
tion in  a  bottle  filled  with  boiled  water  and  well  corked ;  but  in  water 
impregnated  with  air,  the  phosphorus  gradually  oxidizes  at  the  expense 
of  the  air,  and  is  converted  into  phosphoric  acid;  hence  the  liquid  acquires 
an  acid  reaction.  When  boiled  with  water,  it  slowly  exhales  hydrosul- 
phuric  acid. — 2.  When  it  is  digested  in  solution  of  potash  or  soda„  the 
phosphorus  is  converted  into  phosphoric  acid,  by  taking  oxygen  both  from 
the  alkali  and  from  the  water, — while  the  alkali-met^  and  the  hydrogen 
of  the  water  combine  with  the  sulphur.  The  products  are  therefore  an 
alkaline  phosphate,  an  alkaline  hydrosulphate,  and  a  polysulphide  of 
the  alkali-metal ;  and  there  finally  remains  a  quantity  of  phosphorus  £ree 
from  sulphur,  which  solidifies  on  cooling. 

Disulphide  of  phosphorus  dissolves,  with  the  aid  of  heat,  an  additional 
ouantity  of  phosphorus;  but  deposits  it  again  in  the  form  of  rhomboidal 
aodecahedrons  on  cooling. 

h.  Bed  Modijicaiion,  Formed  when  the  preceding  substance,  or  the 
liquid  protosulphide  of  phosphorus  next  to  be  described  ^p.  212),  is  gently 
heated  in  contact  with  an  electro-positive  metallic  sulphide.  It  is  best 
prepared  as  follows  : — A  layer  of  anhydrous  carbonate  of  soda  two  inches 
thick  is  placed  in  a  tube  six  or  eight  inches  long,  and  a  quantity  of  liquid 
protosulphide  of  phosphorus  poured  upon  it,  drop  by  drop,  tiU  the  car- 
bonate of  soda  is  slightly  impregnated  with  the  liquid  throughout.  The 
tube  is  then  closed  with  a  cork,  through  which  a  gas-deHvery  tube  passes, 
and  immersed  in  a  sand-bath,  to  such  a  depth  that  the  level  of  the  sand  may 
be  a  little  above  that  of  the  salt  within  the  tube.  The  sand-bath  is  raised 
to  a  temperature  sufiicient  to  maintain  the  water  in  a  vessel  placed  beside 
the  tube  in  a  state  of  constant  ebullition.  On  withdrawing  the  tube  from 
the  sand  from  time  to  time,  it  is  found  that  the  mass  first  turns  yellow 
without  fusing,  and  afterwards  assumes  a  red  colour,  which  commences  at 
the  bottom,  and  gradually  extends  itself  upwards,  increasing  at  the  same 
time  in  intensity.  Above  the  saline  mass  there  is  deposited,  on  the  sides 
of  the  tube,  a  spontaneously  inflammable  sublimate  of  phosphorous  acid, 
formed  at  the  expense  of  the  air  already  contained  in  the  tube,  and  of 
that  which  enters  slowly  and  insensibly  through  the  gas-delivery  tube. 


DISULPHIDE  OF  PHOSPHORUS.  211 

As  soon  as  the  red  colour  ceases  to  spread  any  farther^  tlie  tube  is  with- 
drawn from  the  sand-bath  and  left  to  cool.  When  it  is  perfectly  cold,  it 
must  be  scratched  with  a  file,  a  line  or  two  below  the  upper  limit  of  the 
red  tint,  then  broken  at  that  point,  and  the  two  ends  immediately 
thrown  into  separate  vessels  of  water;  the  sur£Eu$es  of  the  saline  mass 
would  take  fire  instantly  on  coming  in  contact  with  the  air.  The  water 
dissolves  out  a  quantity  of  sulphophosphite  of  sodium  and  of  phosphate 
and  carbonate  of  soda,  while  a  red  powder  is  left  behind.  This  is  to  be 
well  washed  with  cold  water,  previously  freed  from  air  by  boiling,  and 
then  left  to  dry  on  the  filter  placed  upon  blotting-paper  to  abson)  the 
moisture.  If  it  were  dried  in  vacuo  over  sulphuric  acid,  it  would  take 
fire  as  soon  as  the  air  was  readmitted ;  and  if  it  were  dried  in  the  air 
over  sulphuric  acid,  it  might  also  take  fire  when  withdrawn  from  under 
the  bell-jar,  in  consequence  of  the  heat  produced  by  the  rapid  condensa- 
tion of  the  aqueous  vapour.  If  it  contains  the  minutest  portion  of  liquid 
protosulphide  of  phosphorus,  it  is  sure  to  take  fire  during  the  process  of 
dryiuff.  The  powder  obtained  by  this  process  is  the  red  disulphide  of 
phosphorus.  By  the  action  of  heat  on  the  mixture  of  carbonate  of  soda 
and  protosulphide  of  phosphorus,  sulphophosphite  of  soda  and  disulphide 
of  phosphorus  are  formed.  If  the  quantity  of  protosulphide  is  too  small, 
phosphorus  is  set  free ;  and  when  it  is  too  great,  other  red  compounds  are 
produced  containing  less  phosphorus.  It  is  essential  therefore  that  the 
protosulphide  be  not  added  in  excess.  The  phosphorous  acid  deposited 
above  the  saline  roaas  is  chiefly  produced  from  phosphorus  which  cannot 
find  sufficient  sulphur  to  combine  with :  this  portion  of  phosphorus  sub- 
limes at  a  temperature  at  which  the  red  dLsnlphide  is  fixed.  If  the  tem- 
perature rises  during  the  preparation  (which  however  can  hardly  happen 
with  an  ordinary  sand-batl^,  the  mass  blackens  without  fusing;  the 
phosphorus  reduces  the  carbonic  acid,  and  a  Quantity  of  charcoal  Lb  ob- 
tained impregnated  with  phosphorus  and  mixed  with  phosphate  and  me- 
taphosphate  of  soda,  besides  persulphide  of  sodium. 

Properiiei,  Red  disulphide  of  phosphorus  is  of  a  beautiful,  deep,  ver« 
milion-colour,  much  like  that  of  phosphoric  oxide  prepared  in  the  dry 
way,  but  purer.  It  is  always  in  the  state  of  powder;  and  when  examined 
by  the  microscope,  exhibits  brilliant  anguutf  surjbces,  indicative  of  a 
crptalline  structure;  but  the  smallest  grains  of  it  are  opaque.  It  has 
neither  taste  nor  smell.  Heated  in  a  small  distillatory  apparatus  filled 
with  hydrogen  gas,  it  volatilizes  without  fusing.  At  the  same  time,  its 
colour  oecomes  less  intense,  and  ultimately  black  or  black- brown;  but  on 
cooling,  it  regains  its  original  colour.  During  the  application  of  the 
heat,  it  continuallv  diminishes  in  bulk,  and  a  colourless  liquid,  which  is 
the  liquid  disulphide  of  phosphorus,  condenses  in  the  receiver.  Hence  it 
appears  that  this  substance,  in  assuming  the  gaseous  state,  passes  from  the 
red  to  the  ordinary  modification ;  but  this  change  does  not  take  place  till 
the  temperature  is  raised  above  the  boiling  point  of  the  latter.  Pure 
nitric  acid  of  density  1*22  has  no  action  on  this  compound  at  first;  but, 
after  a  certain  time,  it  dissolves  suddenly  and  with^'great  violence.  By 
less  concentrated  nitric  acid,  it  is  not  attacked  without  the  aid  of  heat. 

Red  disulphide  of  phosphorus  combines  with  sulphur-bases,  imitating 
in  this  respect  the  behaviour  of  phosphoric  oxide  with  oxygen-bases.  In 
the  resulting  compounds,  the  disulphide  and  the  sulphur-base  contain  equal 
quantities  of  sulphur.     The  compounds  are  called  I{ypo8ulphopho9phite$, 

p  2 


212  SULPHUR, 

II.    Protosulphide  op  PHOspnoRns.    PS. 

ffyp<hitilphopho8phorie    acid,    Phosphoric    ffyposulphide,    Hypomlphide 
phosphorique,  Unterphogphoriges  Stdfd. 

a.  Ordinary  Modification,  Preparation,  By  fusing  together  one  atom 
of  sulpbor  and  one  atom  of  phosphorus,  in  the  same  manner  as  in  the  pre- 
paration of  the  disulphide.  The  compound  is  apt  to  become  tnrbid,  from 
the  formation  of  phosphoric  oxide  at  the  expense  of  the  oxygen  of  the  air. 
This  oxide  first  forms  on  the  surface  of  the  liquid,  but  afterwards  sinks  into 
it  and  remains  for  a  long  time  in  suspension,  the  liquid  ultimately  becoming 
clear.  The  best  mode  of  clearing  it  is  to  collect  it  in  water,  making  it  run 
into  that  liquid  &om  a  glass  tube  drawn  out  at  the  end,  and  under  the  pres- 
sure of  a  high  column  of  water.  Another  method  is  to  wrap  a  piece  of  linen 
round  the  end  of  a  glass  tube, — ^pour  the  sulphide  of  phosphorus  into  the 
tube-— then  pour  a  quantity  of  water  on  the  top  of  it,  and  force  the  liquid 
through  the  linen  by  means  of  a  piston .  The  clarification  may  also  be  effected 
by  agitation  with  ammonia;  but  this  occasions  partial  decomposition. 

Properties,  Transparent,  yellow  liquid,  not  very  mobile ;  re&ucts 
light  strongly.  Odour,  strong  and  repulsive,  recalling  that  of  phosphorous 
acid  and  of  chloride  of  sulphur  at  the  same  time.  The  odour  of  phos- 
phorous acid  arises  from  the  formation  of  that  acid  when  the  liquid  comes 
in  contact  with  the  air.  Protosulphide  of  phosphorus  may  be  distilled 
without  alteration  in  an  atmosphere  free  from  oxygen.  It  is  colourless  in 
the  gaseous  state.  At  a  certain  number  of  decrees  below  0°,  it  solidifies 
and  forms  a  colourless  mass  of  small  interlaced  crystals;  but  its  crystal- 
lizing point  is  lower  than  that  of  the  disulphide.  It  fumes  in  the  air  and 
is  luminous  in  the  dark ;  likewise  emits  light  when  vaporized  in  nitrogen 
or  hydrogen  gas  freed  from  ox3rgen.  It  adheres  strongly  to  dry  solid 
bodies:  if  a  small  quantity  of  it  gets  attached  to  the  fingers,  it  can- 
not be  removed  by  water,  even  with  the  aid  of  soap,  unless  the  skin  be 
previously  rubbed  with  oil.  Takes  fire  easily  in  the  air  at  a  slightly  ele- 
vated temperature,  burning  with  a  bright  fiame,  like  that  of  phosphorus, 
and  emitting  a  thick  smoke.  It  does  not  take  fire  spontaneously  when  a 
drop  of  it  is  let  fall  on  a  solid  body;  but  when  absorbed  by  a  porous  body 
and  exposed  to  the  air,  it  soon  becomes  heated  and  takes  nre. 

Calculation.  Bcrzelius. 

P  31-4  66-24  66-192 

S  160  33-76  33-808 


PS 47-4  100-00  100000 

(P»S  =  2  .  196-14  +  201-17  =  593-45.    BeraeUoa.) 

Decompositions,  1.  When  protosulphide  of  phosphorus  evaporates 
slowly  in  a  confined  space  (as  a  bell-jar)  filled  with  moist  air,  which  is 
slowly  but  continually  renewed,  it  is  converted  by  oxidation  into  sulphuric 
and  phosphoric  acids,  which  are  deposited  in  the  form  of  aqueous  solution 
on  the  sides  of  the  vessel  and  around  the  liquid  itself. — 2.  In  a  limited 
atmosphere  of  dry  air  slowly  and  continually  renewed  (as  in  a  glass  tube 
imperfectly  closed  by  a  cork)  it  is  gradually  converted,  in  the  course  of 
three  weeks,  into  phosphorous  acid,  which  forms  a  white  mass  in  the 
upper  part  of  the  tube,  and  takes  fire  on  removing  the  cork ;  persulphide 
of  phosphorus  (p.  218),  which  crystallizes  at  the  bottom  of  the  liquid;  and 


PROTOSULPHIDB  OF  PHOSPHORUS.  213 

a  brown  substance,  which  collects  on  the  sides  of  the  tube,  in  a  layer  of 
continually  increasing  thickness, — and  is  resolved  by  digestion  in  water  for 
half  an  hour,  into  phosphoric  and  sulphuric  acids,  and  hydrated  phosphoric 
oxide. — 3.  Placed  in  a  tube  imperfectly  closed  by  a  cork,  and  heated  in  a 
sand-bath,  it  is  converted  into  a  white,  spontaneously  inflammable  mass, 
consisting,  for  the  most  part,  of  phosphorous  acid. — 4.  Water  has  but 
very  little  action  on  this  liquid.  If  it  be  kept  for  a  few  days  in  a  closed 
vessel  filled  with  boiled  water,  no  visible  change  takes  place;  but  on 
opening  the  vessel,  the  odour  of  sulphuretted  hydrogen  is  emitted.  When 
it  is  kept  under  water  impregnated  with  air  in  an  open  vessel,  sulphur  is 
deposited,  and  renders  the  water  turbid ;  but  the  action  is  so  slow,  that 
the  sulphide  suffers  no  perceptible  diminution,  even  in  the  course  of 
several  months. — 5.  With  alcohol,  ether,  and  oils,  both  fixed  and  volatile, 
it  behaves  like  the  disulphide.  —  6.  It  is  decomposed  by  digestion  with 
caustic  alkalis,  the  products  being  an  alkaline  phosphate  and  hydrosul- 

Ehate,  and  a  polysulphide  of  the  alkali-metal,  all  of  which  dissolve  in  the 
quid,  so  that  nothiug  remains  but  a  small  quantity  of  phosphorus  free 
from  sulphur. — 7.  When  it  is  heated  gently  in  contact  with  a  metallic 
sulphide  in  an  atmosphere  free  from  oxygen,  great  heat  is  evolved,  and  a 
considerable  portion  of  the  liquid  distils  over  with  almost  explosive 
violence:  at  the  same  time,  a  hyposulphophosphate  of  the  metal  is 
produced,  in  which  the  sulphide  of  phosphorus  exists  in  a  peculiar  iso- 
meric state. — 8.  On  digesting  this  compound  with  metallic  solutions, 
sulphides  of  the  metals  containing  variable  quantities  of  hyposulphophos- 
phate are  slowly  deposited.  The  variation  in  the  results  arises  from 
oxidation  of  the  phosphorus  at  the  expense  of  the  metallic  solution,  the 
quantity  thus  oxidized  depending  upon  the  temperature  and  the  concen- 
tration of  the  solution.  The  salts  thus  formed  contain  sulphide  of  phos- 
phorus in  a  different  isomeric  condition  from  that  obtained  in  the  dry 
way.  From  solutions  of  easily  reducible  metals,  such  as  silver,  nothing 
but  a  sulphide  of  the  metal  is  precipitated.  Copper  gives  a  precipitate  of 
hyposulphophosphate.  With  ammoniacal  solution  of  dichloride  of  cop- 
per, a  dark-red  precipitate  is  obtained,  resembling  suboxide  of  copper. 
Sulphate  of  copper  mixed  with  a  sufficient  quantity  of  ammonia  to  form  a 
blue  liquid  gives,  with  protosulphide  of  phosphorus,  a  dark-brovm  pre- 
cipitate. Both  these  precipitates  are  hyposulphophosphates  of  copper; 
but  the  former  is  of  a  minimum,  the  latter  of  a  maximum  degree  of  sul- 
phuration.  When  these  salts  are  exposed  to  the  air,  they  become  acid 
from  oxidation  of  the  phosphorus.  They  should  therefore,  after  washing, 
be  rapidly  pressed  between  folds  of  bibulous  paper,  and  then  dried  in 
vacuo  over  sulphuric  acid. 

Comhinations. — a.  With  Disulphide  of  Phosphorus.— 6.  With  sulphur- 
bases,  forming  salts  called  Hyposulphophosphates,  which  are  the  analogues 
of  the  hypophosphites :  its  capacity  of  saturation  is  such  that  the  sulphur- 
acid  and  sulphur-base  in  these  salts  contain  equal  quantities  of  sulphur, 
-^c.  With  oils,  both  fixed  and  volatile. 

b.  Red  Modification.  Obtained  by  decomposing  hjrposulphophosphate 
of  manganese  by  hydrochloric  acid.  Protosulphide  of  manganese,  pre- 
pared by  precipitating  a  proto-salt  of  manganese  by  hydrosulphate  of 
ammonia,  washing  the  precipitate,  drying,  and  gently  heating  it  in  a  cur- 
rent of  hydrosulphuric  acid  gas,  is  introduced  into  the  middle  bulb  of  a 
tabe  having  three  bulbs  blown  upon  it,  and  a  quantity  of  liquid  protosul- 


S14  SULPHUK. 

phide  of  phoephorofl,  efficient  to  moisten  it  thoronghly,  poured  iipon  it  bj 
means  of  a  pipette.  Hydrogen  gaa  preyionslv  dried  bj  chloride  of  cal- 
cium is  then  passed  through  the  tube,  so  as  to  driye  out  the  air  as  quicklj 
as  possible,  and  the  middle  bulb  gently  heated  by  a  qpirit-lamp.  Under 
these  circumstances,  the  sulphide  of  phosphorus  combines  with  the  sul- 
phide of  manganese ;  and  so  much  heat  is  evolred,  that  the  excess  of  8ul<- 
phide  of  phosphorus  is  driven  with  violence  from  the  middle  bulb  into  the 
other  two.  It  is  afterwards  transferred  in  the  direction  of  the  current  of 
hydrogen  gas,  from  the  bulb  nearest  to  the  chloride  of  calcium  tube  into 
the  middle  bulb,  and  lastly  into  the  further  one.  When  it  has  been  com- 
pletely expelled  from  the  first  two  bulbs,  the  apparatus  is  left  to  cool,  the 
cun-ent  of  hydrogen  gas  being  passed  through  it  all  the  time.  The  heal 
applied  in  this  process  must  be  very  gentle:  a  spirit-lamp  having  ita 
wick  raised  just  enough  to  give  a  pale  blue  flame  should  be  held  u>out 
two  inches  from  the  bulb ;  and  even  this  is  sometimes  too  strong.  The 
colour  of  the  required  compound  is  yellowish  green ;  but  if  the  tempera- 
ture rises  too  high,  the  darker  green  colour  of  protoeulphide  of  manganese 
appears  at  the  lower  part  of  the  bulb.  When  this  happens,  the  apparatus 
must  be  allowed  to  cool,  so  that  the  sulphide  of  phosphorus  may  be 
reabsorbed,  and  the  bulb  again  very  gently  heated.  The  yellowish-green 
substance  obtained  when  the  process  is  properly  conducted  is  the  hypo- 
sulphophosphate  of  manganese,  MnS,  PS.  On  digesting  it  in  hydrochlorio 
acid,  the  manganese  is  dissolved  in  the  form  of  chloride— hydrosnlphnric 
acid  is  evolved — and  an  orange-colonred  powder  is  left,  which  is  a  pro* 
tosulphide  of  phosphorus. 

MnS,  PS  +  Ha  «  MnCl  -f  HS  +  PS. 

Properties.  Orange-coloured  powder,  inclining  to  yellow,  closely  re- 
sembling phosphoric  oxide  prepared  in  the  wet  way.  Tasteless  and 
inodorous.  Inalterable  both  in  air  and  water.  By  <uy  distillation,  it  is 
converted  into  the  liquid  protosulphide,  without  previous  fusion.  Assumes 
a  darker  colour  when  heated,  but  regains  its  original  tint  on  cooling. 
Takes  fire  in  the  air  at  a  temperature  near  100^,  and  bums  with  a  very 
bright  flame,  emitting  a  thick  smoke. 

Decompositions.  1.  When  this  compound  is  digested  in  excess  of 
strong  caustic  potash  at  ordinary  temperatures,  phosphuretted  hydrogen 
gas  of  the  less  inflammable  variety  is  disengaged,  and  the  alkali  dissolves 
small  quantities  of  phosphoric  acid  and  tersulphide  of  phosphorus.  On 
the  application  of  heat,  the  whole  is  dissolved,  yielding  the  same  products 
as  the  liquid  modification  (p.  213). — 2.  Caustic  ammonia  dissolves  it,  but 
not  without  great  difficulty.  The  solution  has  a  strong  yellow  colonr, 
and  yields  on  spontaneous  evaporation,  a  soft,  yellow,  semi-transparent 
mass,  which,  when  treated  with  water,  leaves  a  small  quantity  of  proto- 
sulphide of  phosphorus,  of  a  deep  yellow  colour  and  pulverulent  con- 
sistence; whilst  another  portion  dissolves,  and  may  be  precipitated  by  an 
acid.  In  this  case,  a  small  quantity  of  hypophosphite  of  ammonia  is 
formed,  together  with  a  substance  but  slightly  soluble  in  water.  This 
latter  substance  is  composed  of  sulphide  of  ammonium  and  protosulphide 
of  phosphorus,  probably  with  an  excess  of  the  latter,  which  dissolves  on 
washing  the  undissolved  matter,  and  leaves  a  slight  residue  of  protosul- 
phide of  phosphorus  containing  ammonia.  Acids  precipitate  the  protosul- 
phide of  phosphorus  from  these  solutions  in  the  form  of  yellow  flakes, 
which  have  a  deeper  colour  in  the  cold  than  when  heated. 


TKRSULPHIDB  OF  PHOSPHORUS.  215 

Cbniinnaiiont  With  red  disolphide  of  pho8pliorua.^->Prc^am^M>n. 
Sulphide  of  zino  is  prepared  by  preoipitatiDg  a  zino-salt  with  hydro- 
sulphate  of  ammonia,  and  afterwards  treated  with  liquid  protosulphide 
of  phosphorus,  as  in  the  preparation  of  hyposulphophosphate  of  man- 
ganese. It  is  sufficient,  however,  to  use  a  tube  with  two  bulbs,  inas- 
much as  the  heat  developed  is  not  so  great  as  in  the  former  case.  The 
sulphide  of  zinc  is  first  converted  into  yellow  hyposulphophosphate  of 
zinc;  but  afterwards,  when  the  heat  is  continued  tiU  all  the  liquid  proto- 
sulphide of  phosphonis  condensed  in  the  first  bulb  is  driven  over  into  the 
second,  it  is  converted  into  a  compound  of  1  atom  of  hyposulphophosphate 
with  1  atom  of  sulphide  of  zinc,  saturated  with  1  atom  of  disulphide  of 
phosphorus.  This  compound  is  of  a  fine  red  colour  throughout,  and  yields 
a  powder  resembling  red  lead  in  external  appearance.  A  liquid  distils 
over  containing  less  phosphorus  than  the  protosulphide,  and  depositing 
crystals  which  have  not  been  examined,  but  probably  consist  of  pentasul- 
phide  of  phosphorus.  When  the  red  compound  just  mentioned  is  treated 
with  strong  hydrochloric  acid,  the  sulphide  of  zinc  contained  in  it  is  dis- 
solved, with  disengagement  of  hydrosulphuric  acid,  and  there  remains  a 
red  mass,  which,  after  washing,  may  be  dried  either  over  sulphuric  acid  or 
by  simple  exposure  to  the  air. 

This  substance  is  a  compound  of  protosulphide  and  disulphide  of 
phosphorus. 

Calcidation.  Beneliiu.  Or:  By  Calcolatioii. 

3P  94-2  74-96  74-52  P*S  78-8  6244 

2S  32-0  25-04  2548 PS    474  37-56 

P*S« 126-2  100-00  10000  P«S  +  PS  ....126*2  10000 

(P*S  +  P«S  =  985-73  +  593-45  =  157918.    BeraeUufl.) 

It  is  of  a  bright-red  colour,  like  red  lead.  Has  neither  taste  nor 
smell,  and  is  unalterable  in  the  air.  When  submitted  to  dry  distillation, 
it  is  converted  into  a  liquid  of  the  same  composition :]  hence,  it  con- 
tains the  red  modification  of  phosphorus.  Takes  fire  above  100^,  burning 
with  a  bright  flame,  and  diffusing  a  thick  smoke.  Dissolves  in  boiling 
liquid  protosulphide  of  phosphorus,  forming  a  red  solution;  and  when  the 
liauid  IS  distilled  off,  the  compound  remains  in  the  form  of  a  dark-red 
caKO,  rather  soft,  and  capable  of  being  scratched  by  the  nail. 


III.    Tersitlphtdb  op  Phosphorus.    PS*. 

SulpkophogpharouB  add,    Photphorous   Sulphide,    Suljide   pJioiphoreux, 
Fhoiphorige$  SvXfid. 

Discovered  by  SeruUas,  who  obtained  it  by  the  action  of  hydrosul- 
phuric acid  on  terchloride  of  phosphorus,  but  did  not  further  examine  it. 
\vid.  p.  207). 

Other  modes  of  preparation,  1.  Red  protosulphide  of  phosphorus  is 
mixed  with  the  quantity  of  sulphur  required  to  convert  it  into  the  tersul- 
phide  (1  atom  of  PS  to  2  atoms  of  S),  and  the  mixture  heated  in  a  small 
retort.  The  heat  evolved  at  the  moment  of  combination  is  so  great,  that 
a  small  portion  of  the  mass  is  volatilized  with  violence.  The  whole  then 
fuses  uniformly,  and  ultimately  sublimes  in  the  form  of  a  transparent 
crystalline  substance  of  a  pale  lemon-yellow  colour.    If  the  distillation  be 


216  SULPHUR. 

interrapted  before  the  whole  is  volatilized,  the  uusablimed  portion  retains 
a  reddish  colour  while  hot,  but  on  cooling  acquires  the  same  colour  as  the 
sublimed  portion.  The  vapour  is  but  slightly  coloured. — 2.  One  atom  of 
hyposulphophosphate  of  manganese  is  intimately  mixed  with  2  atoms  of 
sulphur,  and  the  mixture  heated  in  a  small  retort  in  an  atmosphere  free 
from  oxygen,  till  nothing  but  protosulphide  of  manganese  remains.  Ter- 
sulphide  of  phosphorus  is  then  obtained  in  the  form  of  a  sublimate.  If  a 
h3rposulphophosphate  be  employed,  the  base  of  which  does  not  so  readily 
give  up  its  sulphur-acid — hyposulphophosphate  of  silver  for  example — 
only  half  of  the  tersnlphide  of  phosphorus  sublimes,  while  the  rest  remains 
in  combination,  in  the  form  of  sulphophosphite  of  silver.  The  principle  of 
this  reaction  is,  that  one  atom  of  the  sulphur-base  is  saturated  by  one  atom  of 
protosulphide  of  phosphorus,  whereas  one  atom  of  tersnlphide  of  phosphorus 
requires  2  atoms  of  a  sulphur-base  to  saturate  it:  consequently,  2  atoms  of 
hyposulphophosphate  produce  1  atom  of  sulphophosphite  and  1  atom  of 
tersnlphide  of  phosphorus : 

2(MS,PS)  +  4S  =  2MS,PS»  +  PS». 

Properties.  This  compound  is  a  solid  substance,  of  a  pale  yellow 
colour.  After  fusion  or  sublimation,  it  remains  soft,  like  plastic  sulphur, 
and  does  not  become  opaque  till  it  hardens.  Sublimes  at  a  temperature 
below  the  subliming  point  of  sulphur.  When  heated  in  the  air,  it  bums 
with  a  whitish -yellow  flame,  and  diffuses  a  thick  smoke.  In  moist  air,  it 
decomposes  rapidly,  becoming  white  and  assuming  an  acid  reaction,  in 
consequence  of  the  formation  of  phosphoric  acid :  at  the  same  time,  it 
acquires  a  bitter  and  hepatic  taste.  This  decomposition  in  the  air  takes 
place  so  rapidly,  that  the  substance  can  only  be  preserved  in  vessels  her- 
metically sealed.  The  unsublimed  reddish  tersnlphide  decomposes  in  the 
same  way. 

Tersnlphide  of  phosphorus  is  rapidly  dissolved  by  caustic  alkalis  and 
by  ammonia.  The  solutions  have  a  pale  yellow  colour,  and  when  treated 
with  acids,  yield  a  light,  fiocculent,  and  nearly  white  precipitate,  which 
falls  down  slowly,  and  has  a  pale  yellow  colour  when  collected  in  a  mass: 
this  precipitate  may  be  washed  and  dried.  Tersnlphide  of  phosphorus  in 
this  state  is  less  rapidly  decomposed  by  exposure  to  the  air  than  that 
which  has  been  fused  or  sublimed.  It  is  uncertain  whether  the  difference 
thus  produced  by  the  influence  of  an  alkali  depends  upon  an  isomeric 
modification.  Tersulphide  of  phosphorus  is  easily  dissolved  in  the  cold 
by  carbonate  of  potassa  or  soda;  but  deposits  sulphur  at  the  same  time — 
a  proof  that  decomposition  takes  place. 

Calculation.  Berzelius. 

P     31-4  39-55  39-394 

3S     48-0  60-45  60-606 

PS^     79-4  100-00  100-000 

(P«S*  =  2  .  196*14  +  3  .  201-17  =  995-79.    BerzeUus.) 

Combinations.  Tersulphide  of  phosphorus,  or  SiUphopJiosphorotu  acid 
combines  with  sulphur-bases,  forming  a  class  of  sulphur-salts  called  SuU 
p/iophospkites,  which  are  the  analogues  of  the  phosphites.  One  atom  of 
the  sulphur-acid  is  saturated  by  2  atoms  of  a  sulphur-base,  just  as  one 
atom  of  phosphorous  acid  is  saturated  by  2  atoms  of  an  oxygen-base. 


PENTASULPHIDE  OF  PHOSPHORUS.  21? 

IV.    Pentasulphide  op  Phosphorus.    PS*. 

Sulphophosphoric  acid,  Phosphoric  Sulphide,  Sulfide  phosphorique,  Phos- 

phorsulfid. 

This  compound  is  formed  when  sulphur  and  phosphorus  combine  with 
explosion  and  development  of  light,  being  deposited  in  the  form  of  a  light, 
transparent,  pale-yellow  film  on  the  bodies  on  which  it  cools.  This  mode 
of  formation  is  not,  however,  practically  useful. 

Preparation,  1.  One  atom  of  solid  protosulphide  of  phosphorus  is 
mixed  with  4  atoms  of  sulphur,  and  the  mixture  heated  in  an  atmosphere 
free  from  oxygen,  till  the  two  substances  unite.  The  act  of  combination 
is  attended  with  a  sudden  disengagement  of  heat,  by  which  a  portion  of 
the  substance  is  rapidly  sublimed;  but  there  is  no  explosion  or  production 
of  light. — 2.  One  atom  of  hyposulphophosphate  of  manganese  is  heated 
with  4  atoms  of  sulphur :  the  required  compound  sublimes  at  a  gentle  heat, 
leaving  protosulphide  of  manganese.  Hyposulphophosphate  of  silver 
heated  with  4  atoms  of  sulphur  jrields  sulphophosphate  of  silver,  while 
half  of  the  pentasulphide  of  phosphorus  sublimes. 

Pentasulphide  of  phosphoras  is  likewise  formed,  when  the  liquid 
protosulphide  is  heated  in  a  current  of  hydrosulphurio  acid  gas.  A  pale 
liquid  distils  over,  which  is  a  solution  of  the  pentasulphide  in  the  liquid 
protosulphide,  and  yields  a  small  quantity  of  the  former  in  crystalline 
scales. 

Properties,  This  compound  is  of  a  pale-yellow  colour,  like  the  ter- 
sulphide— but  crystallizes.  When  it  is  sublimed  very  slowly,  and  in  such 
a  manner  that  it  can  form  isolated  crystals,  these  crystab  are  transparent, 
and  have  so  little  yellow  colour,  that  they  appear  perfectly  colourless 
when  thin :  their  faces  are  deeply  striated.  When  the  liqjuid  penta- 
sulphide is  distilled,  it  assumes  a  crystalline  form  in  solidify mg,  and  is 
then  easily  detached  from  the  glass.  When  solidified  by  sudden  cooling, 
it  does  not  crystallize,  but  forms  a  mass,  sometimes  yellow  and  trans- 
parent, sometimes  whitish  and  opaque.  When  obtained  by  fusion  from  the 
red  protosulphide  of  phosphorus,  it  does  not  crystallize  on  cooling,  unless 
it  be  first  sublimed.  After  being  fused  and  heated  to  the  boiling  point, 
it  has  a  deeper  colour,  like  that  of  sulphur.  Its  boiling  point  is  higher 
than  that  of  sulphur,  and  the  colour  of  its  vapour  is  a  less  intense  yellow 
than  that  of  sulphur  vapour.  When  heated  in  the  air,  it  bums  with  a 
pale  phosphoric  flame,  and  difl'uses  a  large  quantity  of  smoke.  In  moist 
air,  it  is  decomposed  almost  as  easily  as  tersulphide  of  phosphorus,  and 
transformed  into  a  white  mass  impregnated  with  phosphoric  acid.  It 
dissolves  in  caustic  alkalis  and  in  ammonia  much  in  the  same  manner  as 
a  deliquescent  salt  dissolves  in  water.  The  solution  has  a  pale-yellow 
colour  :  acids  precipitate  sulphur  from  it,  and  cause  an  abundant  evolution 
of  hydrosulphuric  acid.  It  appears  as  if  no  alkaline  sulphophosphate 
could  exist  in  contact  with  water.  The  carbonates  of  potassa  and  soda 
slowly  dissolve  the  pentasulphide  of  phosphorus  in  the  cold,  producing 
at  the  same  time  an  abundant  deposit  of  flakes  of  sulphur.  On  heating 
the  liquid  to  about  60^,  the  sulphide  of  phosphorus  dissolves  with  violence, 
and  inodorous  carbonic  acid  gas  is  evolved  :  no  deposition  of  sulphur 
takes  place.  When  boiled,  the  liouid  evolves  carbonic  and  hydrosulphurio 
acid  gases  together.  The  composition  of  pentasulphide  of  phosphorus  is 
as  follows : 


218  SULPHUR. 

Calcalation.  Berzeliiu. 

P    31-4  28-19  28-06 

5S    80-0  71-81  71-94 

PS*   111-4  10000 100-00 

(P>S»  »  2  .  19614  +  5  .  201-17  =  139813.    BeneUu.) 

CcmbiiuUioM.  Pentasalpbide  of  phosphonui  oombinea  with  salphur- 
basM,  fonning  nalts  called  Sulphophoiphate$.  One  atom  of  it  aatarates 
2  atoms  of  a  sulphur-base,  jast  as  1  atom  of  pjrophosphoric  aoid  saturates 
2  atoms  of  an  oxjgen-base  :  hence  the  solphophosphates  are  the  analogues 
of  the  pyrophosphates. 

y.    Pebsulphidb  of  Phosphorus.    PS^'. 

Feriu^re  de  phosphore,  Phosphor-^upersu^uret. 

Preparation,  When  a  small  quantity  of  sulphur  is  dissolved,  with  the 
aid  of  heat,  in  liquid  protosulphide  of  phosphorus,  the  persulphide  is 
obtained  on  cooling,  in  the  form  of  very  re^lar  crystsJs  resembling 
those  of  sulphur.  When  1  atom  of  protosulphide  of  phosphorus  is  fused 
at  a  temperature  not  exceeding  100°  with  2  or  4  atoms  of  sulphur,  nothing 
is  obtained  but  these  same  crystals  of  persulphide,  which  collect  at  the 
bottom  of  the  mother-liquid.  When  the  quantity  of  sulphur  amounts  to 
four  atoms,  the  whole  solidifies  in  a  mass  on  cooling :  but  on  inclining 
the  vessel,  the  protosulphide  drains  out  drop  by  drop  from  the  crystals  <^ 
persulphide.  If  the  temperature  rises  above  100  during  the  fusion^ 
explosion  takes  place,  and  pentasulphide  is  formed :  the  explosion  is  most 
violent  when  4  atoms  of  sulphur  are  used  with  1  atom  of  the  protosulphide. 
When  a  larger  proportion  of  sulphur  is  used,  the  excess  takes  the  form 
of  plastic  sulphur,  and  retains  its  softness  and  viscosity  for  a  long  time. 
It  appears  that  the  conmounds  PS'  and  PS^  are  never  produced  without 
powerful  development  of  light  and  heat.  This  phenomenon  is  much  loss 
marked  when  the  red  modifications  are  operated  upon;  and  hence  it 
might  appear  to  be  due  to  a  change  of  isomeric  condition;  but  the  facility 
with  which  the  resulting  compounds  oxidize  in  the  air  is  unfavourable  to 
this  hypothesis. 

The  best  mode  of  obtaining  the  persulphide  regularly  crystallized^  is 
to  dissolve  1  atom  of  sulphur  in  1  atom  of  liquid  protosulphide  of  phos- 
phorus by  the  heat  of  a  water-bath,  and  then  leave  the  vessel,  carefully 
closed,  to  cool  in  the  bath.  The  crystals  thus  obtained  are  few  in  number, 
but  of  considerable  size,  yellow  and  shining,  and  frequently  present  nu- 
merous £EbcetS|  like  those  of  native  sulphur.  Some  are  cleavable  in  the 
direction  of  the  laminas.  They  are  impregnated  with  protosulphide  of 
phosphorus,  which  adheres  to  them  obstinately,  and  causes  them  to  emit 
slight  fumes  from  the  surface  of  a  recent  fracture.  To  free  the  crystals 
from  the  protosulphide,  they  must  be  dried,  reduced  to  small  pieces,  and 
placed  between  folds  of  bibulous  paper  under  a  bell-jar,  and  by  the  side 
of  a  small  dish  containing  water.  The  edge  of  the  bell-jar  is  slightly 
raised  by  the  insertion  of  a  small  piece  of  wood,  to  allow  of  the  renewal 
of  the  air  within  it.  In  this  manner,  the  protosulphide  adhering  to  the 
crystals  is  converted  into  phosphoric  acid,  sulphuric  acid,  and  persulphide 
of  phosphorus.  Some  time  elapses  before  the  change  is  complete;  but 
sooner  or  later,  the  odour  of  the  protosulphide  disappears  entirely.  The 
crystals  are  then  to  be  washed  and  dried  over  oil  of  vitriol. 


PERSULPHIDE  OF  PHOSPHORUS.  219 

The  orjrfltaLs  thiu  obtained  may  be  exposed  to  the  air  for  a  long 
time,  without  dimination  of  the  lustre  of  the  crystalline  facets ;  but  after 
a  while,  they  redden  litmus  paper  when  placed  upon  it.  In  a  stoppered 
bottle  filled  with  dry  air,  they  may  be  preserved  for  any  length  of  time 
without  alteration.  They  fuse  at  a  temperature  near  the  meltiuff  point 
of  sulphur,  and  then  distil  oyer  without  separation  of  protosulphide  of 
phospnorus.  The  distilled  product  does  not  crystallize,  but  remains  soft 
long  after  cooling.  If  the  persulphide,  when  subjected  to  distillation,  is 
not  quite  free  from  protosulphide,  an  explosion  ta^es  place  on  the  appli- 
cation of  heat,  arising  from  the  formation  of  pentasulpnide.  This  explo- 
sioU)  however,  is  not  yioleni  enough  to  break  the  vessel,  unless  the  Quan- 
tity of  protosulphide  retained  in  the  cr^tals  is  considerable.  But  if  the 
neck  of  the  retort  is  merely  inserted  into  the  receiver,  without  luting, 
the  retort  is  often  thrown  by  the  explosion  to  the  distance  of  sevenl 
feet. 

The  composition  of  persulphide  of  phosphorus  is : 

Calculfttioii.  Benelins. 

P  31-4  1406  13  979 

12S  192-0  85-94  86021 


PS»«  223-4  100-00  100000 

(P»S"  -  2  .  196-14  +  12  .  20117  =  2806-32.    BewcUus.) 

It  dissolves  in  caustic  alkalis,  behaving  like  a  mixture  of  sulphur 
and  protosulphide  of  phosphorus.  The  products  are  phosphate  and 
hyposulphite  of  potassa,  together  with  persulphide  of  potassium. — By 
fusion  at  a  gentle  heat,  persulphide  of  phosphorus  may  be  made  to  take 
up  an  additional  quantity  of  sulphur.     IT 

[Vid.  Berzelius,  TraiU  de  Chimie,  Far.  1845,  I.,  815;  also  Ann. 
Pharm.  46,  129  and  251.] 


B.  Phosphitretteb  Sulphide  of  Carbon. — Bisulphide  of  carbon 
quickly  dissolves  eight  times  its  weight  of  phosphorus,  according  to  Tromms- 
dorff,  and  twenty  times  its  weight,  according  to  Bottger,  without  becoming 
solid.  Any  white  phosphoric  matter  or  phosphoric  oxide  that  may  be  mixed 
with  the  phosphorus  remains  undissolved*.  The  solution  is  specifically 
heavier  than  bisulphide  of  carbon,  and  refracts  light  more  powerfully. 
The  solution,  covered  with  wat«r  and  exposed  to  the  sun's  rays,  becomes 
coated  on  the  surface  with  a  film  of  phosphoric  oxide,  yellow  at  first,  but 
afterwards  turning  red ;  and  when  this  is  removed  by  a  glass  rod,  a  fresh 
film  is  formed, — and  so  on,  continually,  as  long  as  any  phosphorus  remains 
in  the  solution.  ^Bottger.)  According  to  Bdckmann  {A.  Tr,  22,  2,  214), 
it  is  not  reddenea  by  exposure  to  sunshine.  The  greater  the  quantity  of 
phosphorus  contained  in  the  solution,  the  lower  is  the  temperature  at 
which  it  takes  fire  :  at  27°  (49°  F.),  and  on  the  addition  of  iodine  op 
chlorine,  which  causes  evolution  of  heat  in  combining  with  the  phos- 
phorus, the  inflammation  is  instantaneous.  (Brewster.)  The  vapour 
mixed  with  oxygen  gas  explodes  on  the  approach  of  flame.  Paper 
wetted  with  the  solution  takes  fire  spontaneously  after  some  minutes 

*  The  white  and  red  modifications  of  phosphonu  are  insoltible  in  bisulphide  of  car- 
bon:.p.  no.  LW.] 


220  SULPHUR. 

(Lampadins), — ^becanse,  after  the  evaporation  of  the  sulphide  of  carbon^ 
the  phosphorus  remains  behind  in  a  state  of  minute  division;  the  paper 
likewise  takes  fire  when  dipped  in  nitric  acid.  (Brewster.)  A  mixture 
of  the  solution  with  chlorate  of  potassa  detonates  violently  on  being  rub- 
bed, and  is  set  on  fire  by  contact  with  oil  of  vitriol.  (Brewster.^  If  the 
bisulphide  of  carbon  be  distilled  off  out  of  contact  of  air,  colourless  phos- 
phorus remains.  (Lampadius.)  A  solution  of  6  parts  of  phosphorus  in  one 
part  of  bisulphide  of  carbon  deposits  crystals  at  — 2*5°.  (Trommsdorff.) 
Alcohol  precipitates  the  phosphorus.  (Berzelins.)  One  part  of  bisnlphido 
of  carbon  coagulates  with  21  parts  of  phosphorus  into  a  mass  of  the  con- 
sistence of  goose-grease,  which  takes  in  a  few  seconds  on  bibulous  paper, 
and  sometimes^  though  not  often,  on  glass  or  metal.  (Bottger. — Comp. 
Lampadius,  -4.  GeJd.  2,  195  ;  Trommsdorff,  A.  Tr.  17,  1,  35;  Brewster, 
Edinb,  Fhll  J.  5,  222  ;  also  JSchw.  33,  121 ;  Bottger,  Schw.  68,  138  ; 
also  J.  pr.  Chem.  12,  360.) 

C.  S  ULPH ATE  OP  Phosphdretted  H ydrogen. — Oil  of  vitriol  absorbs 
phosphnretted  hydrogen  gas  without  immediate  decomposition.  (Buff.) 
The  solution  kept  out  of  contact  of  air  is  decomposed  in  the  course  of 
four- and- 1 went V  hours,  with  evolution  of  sulphurous  acid,  formation  of 
phosphoric  acid,  and  deposition  of  a  yellow  powder,  consisting  of  sulphur 
free  from  phosphorus.  (H.  Rose.)  According  to  Buff,  however,  it  de- 
posits phosphorus.  The  freshly  prepared  compound  dropped  into  water 
immediately  evolves  non-spontaneously  inflammable  phosphnretted  hy- 
drogen gas,  even  though  the  spontaneously  inflammable  gas  may  have 
been  used  in  preparing  it ;  part  of  the  gas  remains  absorbed  by  the 
watery  liquid.  (H.  Rose.)  Ammoniacal  gas  passed  through  the  freshly 
prepared  solution  liberates  a  quantity  of  phosphnretted  hydrogen  equiu 
to  that  which  has  been  absorbed.  (Buff,  Pogg,  16,  366;  H.  Rose,  Pogg. 
24,  139.) 

Anhydrous  sulphuric  acid  is  instantly  decomposed  by  contact  with 

fihosphuretted   hydrogen,   without  entering  into  combination   with   it 
H.  Rose.) 


%  D.      SULPHOXYPHOBPHORIC  AciD.      PO'S*. 

Sulphophospkoric  Acid. 

Wurtz  obtained  this  compound  by  the  action  of  solution  of  caustic 
soda  on  the*  chloride  of  sulphur  of  SeruUas,  PCl'S*  {vid.  Chap.  X.). 
When  the  materials  are  put  into  a  retort,  and  subjected  to  the  heat  of  a 
water-bath,  ebullition  takes  place,  and  part  of  the  chloride  distils  over 
into  the  receiver.  When  the  whole  of  the  chloride  has  disappeared,  the 
liquid  in  the  retort  is  allowed  to  cool.  It  generally  forms  into  a  solid 
crystalline  mass :  this  is  to  be  drained,  and  the  crystals  purified  by 
repeated  solution  in  water  and  crystallization.  The  reaction  is  as 
follows : 

PCI*  S«  +  6NaO  =  3NaO,  PO»S«  +  3  NaCl. 

The  soda  must  be  in  excess  ;  because  the  free  acid  in  solution  is  readily 
decomposed  into  phosphoric  acid  and  sulphuretted  hydrogen  : 
PO»S«  +  5HO  =  3H0,P0*,  2HS. 

Sulphoxyphosphate  of  soda  is  readily  soluble  in  boiling  water,  and 
crystallizes  on  cooling  in  brilliant  six-sided  tables.     Its  composition  is 


METALLIC  SULPHIDES.  221 

3NaO,  PO^*  +  24HO  ;  analogous,  therefore,  to  the  ordinary  tribasic 
phosphate  :  3NaO,  PO*  +  24HO.  In  fact,  the  acid  may  be  regarded  as 
phosphoric  acid,  in  which  2  atoms  of  oxygen  are  replaced  by  sulphur  ; 
just  as  hypophosphorous  acid  (according  to  Wurtz)  is  phosphoric  acid  in 
which  2  atoms  of  oxygen  are  replaced  by  hydrogen  (vid,  p.  115).  The 
solution  of  sulphoxyphosphate  of  soda  has  a  strong  alkaline  reaction  : 
chlorine,  bromine,  and  iodine  decompose  it  immediately,  with  separation  of 
sulphur,  and  formation  of  ordinary  phosphate  of  soda.  The  weakest 
acids  added  to  the  solution  liberate  sulphoxjrphosphoric  acid,  which  is 
immediately  decomposed  on  boiling.  The  lime,  baryta,  and  strontia  salts 
are  insoluble ;  the  nickel  and  cobalt  salts  turn  black  on  boiling ;  the 
lead-salt  is  white  when  newly  formed,  but  turns  black  in  a  few  hours, 
from  separation  of  sulphide  of  lead.  (Wurtz,  N,  Ann,  Chim,  Phys,  20, 
472  3  abstr.  Ann.  Pharm.  64,  245.)     IT 


Other  Compounds  op  Sulphur. 

A.  With  Selenium.— B.  With  Iodine.— C.  With  Bromine.— D. 
With  Chlorine.  — E.     With  Fluorine. 

F.  With  Metals.  Metallic  Sulphides,  Sulpliurets,  or  Sulphur-bases, 
when  they  are  electropositive, — Sulphur-acids,  when  they  are  electro- 
negative. (The  compound  of  an  alkali-metal  with  sulphur  is  also  called 
Liver  of  Sulphur,     Hepar  Sulphuris.) 

These  compounds  are,  for  the  most  part,  formed  according  to  the  fol- 
lowing proportions  :  1  At.  metal  to  1,  2,  3,  4,  or  5  At.  sulphur, — and  2 
At.  metal  to  1  or  3  At.  sulphur. 

Formation  and  Preparation  of  Anhydrous  Metallic  Sulphides.  1.  By 
bringing  the  metal  in  contact  with  sulphur  at  ordinary  or  at  higher  tem- 
peratures. Finely  divided  copper  (Zimmermann)  and  sodium  (Win- 
kelblech)  combine  with  sulphur  at  ordinary  temperatures  on  being  rubbed 
with  it.  Several  metals,  as  manganese,  tin,  lead,  and  nickel,  combine 
with  sulphur  at  its  boiling  point,  and  consequently  bum  in  its  yapour  : 
others,  as  iron,  do  not  combine  with  it  below  a  red  heat.  The  combina- 
tion of  a  metal  with  sulphur  is  generally  attended  with  vivid  combustion, 
the  sulphur  playing  with  regara  to  the  metal  the  same  part  that  oxygea 
plays  in  ordinary  cases  of  combustion.  When  sulphur  is  heated  in  a, 
glass  flask  till  the  flask  is  filled  with  its  yapour,  thin  leaves  of  copper  or 
silver  (Berzelius),  tin  or  lead  foil,  and  powdered  manganese,  nickel,  or 
copper  (Winkelblech)  burn  in  it  vividly.  A  piece  of  iron  liarpsichord 
wire  also  bums  in  the  vapour,  if  a  small  piece  of  potassium  or  sodium  be 
attached  to  its  extremity  to  commence  the  combustion.  (Winkelblech,. 
Ann.  Pharm,  21,  34.)  If  a  piece  of  sulphur  be  thrown  into  a  gun -bar- 
rel heated  to  redness  at  the  lower  end,  and  the  vapour  blown  out  at  the 
touch-hole,  a  piece  of  wire,  e.  g.  of  iron,  held  in  the  vapour,  burns  with 
a  bright  light,  and  is  converted  into  sulphide.  (Hare.)  Since  the  tempe- 
rature at  which  sulphur  combines  with  most  metals  is  higher  than  its 
boiling  point,  the  greater  part  of  the  sulphur  evaporates  before  the  metal 
has  attained  the  temperature  required  for  combination.  To  ensure  com- 
bination in  spite  of  this  circumstance,  the  following  methods  may  be 
adopted :  (a.)  The  sulphur  may  be  put  into  the  lower  part  of  the  cm- 
cible — the  metal,  in  the  form  of  filings,  e,  ^.iron-filings,  into  the  upper 
part — the  crucible  covered,  and  surrounded  in  the  air-furnace  with  dead 


223  SULPHUR. 

cools,  and  lire  coaLi  heaped  on  the  top  of  it, — so  tbat  the  heat  may  pasB 
from  aboTe  downwards,  and  not  bring  the  solphur  vapour  in  contact  with 
the  metal  till  the  latter  has  attained  the  proper  temperature.  (6.)  A 
small  quantity  of  sulphur  is  placed  at  bottom,  the  mixture  of  metallio 
filings  and  sulphur  placed  upon  it,  and  the  crucible  heated  in  a  similar 
manner,  (c.)  The  metal  is  heated  to  redness  in  a  tube,  and  yapour  of 
sulphur  passed  over  it.  (d,)  The  metal  is  heated  with  sulphur  in  a  close 
vessel  void  of  air ;  the  sulphur  is  converted  into  yapour,  and  the  vapour 
absorbed  by  the  heated  metal. 

2.  By  heating  a  metal  in  hydrosulphuric  acid  gas,  hydrogen  being 
set  free. 

3.  By  igniting  a  metallic  oxide  with  sulphur,  whereby  part  of  the  sul- 
phur is  made  to  combine  with  the  oxygen  of  the  oxide  and  form  hypo- 
sulphurous,  sulphurous,  or  sulphuric  acid,  while  the  remaining  portion 
combines  with  the  metal.  All  fixed  alkalies,  either  free  or  combined  with 
carbonic  acid  (which  is  expelled  without  alteration  during  the  process), 
yield,  when  ignited  with  sulphur,  a  mixture  of  3  atoms  of  metallic  sul- 
phide and  1  atom  of  sulphate.     {Sch,  37.) 

4KO,CO«  +  168  =  3KS»  +  KO,SO*  +  4C0«. 
When  hydrate  of  potassa  is  gently  heated  with  sulphur,  an  alkaline 
hyposulphate  and  a  metallic  sulphide  are  produced.  The  heavy  metallic 
oxides,  on  the  other  hand,  disengage  sulphurous  acid  when  they  are 
decomposed  by  ignition  with  sulphur  :  in  such  cases,  they  either  give  up 
the  whole  of  their  oxygen  to  one  portion  of  the  sulphur,  and  combine 
with  the  remainder  to  form  a  sulphide  (oxide  of  copper,  arsenious  acid ; 
2  AsO*  -f  9S  =  2  AsS'  +  3S0*;  Sch.  100  ;  for  A*  read  As) ;  or  one 
part  of  the  oxide,  generally  about  half,  remains  undecomposed,  and  forms 
a  peculiar  compound  with  the  sulphide  produced  (e.  g.  protoxide  of  man- 
ganese). Many  metallic  oxides  undergo  no  change  by  ignition  with  sul- 
phur ;  but  when  they  are  heated  in  contact  with  a  mixture  of  equal 
weights  of  sulphur  and  carbonate  of  potassa  (whereby  pentasulphide  of 
potassium  is  formed),  gently  at  first,  but  afterwards,  when  the  whole  of 
the  carbonic  acid  is  expelled,  kept  for  half  an  hour  at  a  bright  red  heat 
in  a  covered  porcelain  crucible, — the  mass,  when  cooled  and  digested  in 
water,  yields  sulphide  of  potassium,  while  the  other  metallic  sulphide 
remains  undissolved,  in  the  form  of  a  shining  crystalline  powder.  In  this 
manner,  Berzelius  succeeded  in  forming  the  compounds  of  sulphur  with 
cerium,  chromium,  and  uranium.     Part  of  the  pentasulphide  of  potassium 

J>robab1y  acts  upon  the  oxide  of  the  other  metal,  in  such  a  manner  as  to 
brm  sulphate  of  potassa  and  the  sulphide  of  the  other  metal. 

4.  By  passing  vapour  of  bisulphide  of  carbon  over  the  metallic 
oxide  at  a  red  heat.  The  carbon  unites  with  the  oxygen  of  the  metallic 
oxide  to  form  carbonic  oxide  or  carbonic  acid,  and  the  sulphur  enters 
into  combination  with  the  reduced  metal :  e,  g, 

TiO«  +  CS»  =  TiS«  +  C0«. 

5.  By  decomposing  a  metallic  oxide  with  hydrosulphuric  add.— For 
each  atom  of  oxygen  contained  in  the  oxide,  an  atom  of  sulphur  enters 
into  combination  with  the  metal.  PbO  -f  HS  =  PbS  +  HO  ;  Sck. 
41 ;— Fe»  0«  -j-  3HS  =  Fe»  S'  -f  3H0  ;— SnO»  +  2HS  =  SnS»  -f-  2H0; 
8ck.  42 j— AsO'  +  3HS  =  AsS'  +  3H0;  /SbA.  43  ;— AsO*  -h  5HS  =  As; 
/Sc.  5  +  5H0  \  Sch,  44.— <i.  The  oxide  is  heated  to  redness,  and  hydro- 
sulphuric acid  passed  over  it.  The  sulphide  thus  produced  often 
takes  np  more  sulphur  from  the  hydrosulphuric  acid,  and  sets  hydrogen 


II- 


METALLIC  SULPHIDES.  223 

m  free  (iron) ;    sometimes  abo  it  absorbs  the  hydrosulphorio  aoid  without 

Bsr  decomposiDg  it  (potassiam).-^.  Hjdrosulphurio  acid  gas  is  passed  into 

water  in  which  the  metallic  oxides  or  acids  are  diffused  or  dissolyed. 
»  •— «.  The  metaUio  acids  or  oxides  are  dissolved  in  an  acid,  and  hydro- 

\i  sulphuric  aoid  gas  passed  through  the  solution.     In  this   manner,— 

It  eyen  when  one  of  tne  stronger  acids  is  present  in  excess,  provided 

1.  it  be  not   too   concentrated — the  oxides   and  acids    of   molybdenum, 

9  arsenic,  antimony,  tellurium,  bismuth,  cadmium,  tin,  lead,  copper,  and 

of  the  noble  metals,  are  decomposed.  A  precipitate  is  formed,  consisting 
of  a  pure  anhydrous  sulphide  of  the  metal,  and  never  containing 
undecomposed  oxide— except  in  the  case  of  red  oxide  of  mercury,  the 
salts  of  which — when  the  hydrosulphuric  acid  is  not  used  in  excess — ^are 
partly  precipitated  in  the  undecomposed  state,  together  with  the  sulphide. 
The  reaction  between  many  metallic  oxides  and  hydrosulphuric  acid 
takes  place  at  ordinary  temperatures  (oxide  of  lead) — viz.  when  hydro- 
sulphuric acid,  either  in  the  gaseous  state  or  dissolved  in  water,  is  brought 
in  contact  with  the  oxide,  either  free  or  dissolved  in  an  acid :  in  other 
cases,  a  higher  temperature  is  required  (tungstic  acid).  With  metallic 
oxides  dissolved  in  water,  e,  g.  the  alkalis,  hydrosulpnurio  acid  forms 
solutions  in  which  either  a  hydrated  metallic  sulphide  or  a  hydrosnlphate 
of  the  oxide  may  be  supposed  to  exist :  these  solutions  evaporated  out  of 
contact  of  air  jneld  anhydrous  sulphides. 

6.  Hydro^n  gas  or  charcoal  is  made  to  act  at  a  red  heat  upon  metal- 
lic hyposulphites,  sulphites,  or  sulphates  (pp.  172 — 190). 

KO,  SO*  +  H  =  KS  +  4HO     (Sch.  84.) 
PbO,  SO*  +  2C  =-  PbS  +  2CO«. 

7.  By  double  affinity  :  the  solution  of  a  heavy  metallic  salt  is  preci« 
pitated  by  a  solution  of  the  sulphide  of  an  alkali-metal.  The  sulphide 
of  the  alkali-metal  may  contain  1,  2,  8,  or  5  atoms  of  sulphur,  and  a 
corresponding  number  will  be  transferred  to  the  heavy  metal ;  and  as 
the  metal  may  not  be  capable  of  uniting  with  sulphur  in  all  these  propor- 
tions, uncombined  sulphur  may  be  precipitated  together  with  the  metallic 
sulphide.  A  solution  of  monosnlphide  of  potassium,  for  example,  preci- 
pitates a  monosnlphide  of  the  metal  from  a  solution  of  a  heavy  metallio 
oxide  containing  1  atom  of  oxygen  to  1  metal : 

K8  +  PbO,NO»  -  PbS  +  KO,NO»; 

or  if  we  suppose  that  monosnlphide  of  potassium  when  dissolved  in  water 
is  converted  into  hydrosnlphate  of  potassa : 

KO,HS  +  PbO,NO»=«  PbS  +  KO,NO»  +  HO: 
further : 

3KS  +  Fe«0»,3SO»  +  3HO  «  Fe«S',3HO  +  3(K0.80»); 
or,  3(K0,  HS)  +  Fe«  0»,  3S0»=  Fe»  0»,  H»  S»  +  3(K0,  SO») : 

The  precipitate  consists  of  hydrated  sesqui-sulphide  or  iron,  of  ter-hydro- 
sulphate  of  ferric  oxide : — ^finally : 

KS«  +  HgCl  »  KCl  -»-  HgS  +  48. 
Metallic  sulphides  are  solid  and  brittle  (the  sulphides  of  copper  and 
silver  alone  possess  a  certain  degree  of  ductility):  they  are  generally 
crystalline.  Their  specific  gravity  is  often  below  the  calculated  mean. 
The  light  metallic  sulphides  are  pale  yellow  or  brown,  and  without  me* 
tallic  lustre  :  the  heavy  ones  are  of  various  colours,  mostly  dark :  some 
of  them  are  transparent  without  metallic  lustre  (Blendes);  others  opaque, 
and  possessed  of  metallic  lustre.  {PyrUe$,  Olance$\  The  sulphides  of 
the  easily  fusible  metals  are  less  fusible — those  of  the  more  refractory 


224  SULPHUR. 

metals,  more  fusible  than  the  metals  themselves.     Sulphides  are  mostly 
less  volatile  than  the  pure  metals. 

Decomposition  of  Metallic  Sulphides,  1.  Some  metals  give  up  their 
sulphur  at  a  moderate  heat  (gold);  others  retain  it  even  at  the  highest 
temperatures  (zinc);  or  if  they  are  combined  with  more  than  one  atom 
of  sulphur,  give  up  only  a  part  of  it  (iron,  tin). — 2.  Dry  oxygen  gas  does 
not  act  on  metallic  sulphides  at  ordinary  temperatures ;  the  same  gas 
when  moi»t  slowly  converts  several  of  them  (iron)  into  sulphates.  Ex- 
posed to  the  air  or  oxygen  gas  at  high  temperatures,  they  yield  either 
sulphurous  acid  gas  and  metal  (silver),  or  sulphurous  acid  gas  and  oxide 
(antimony,  Sch.  28,  bismuth,  tin,  and  likewise  iron  when  the  heat  applied 
IS  very  great);  or  else  a  sulphate  (the  alkali-metals;  also  iron  and 
copper  at  a  very  low  red  heat,  Sch.  30).  When  heated  in  a  glass  tube 
open  at  both  ends,  they  yield  sulphurous  acid,  which  may  be  detected  by 
its  odour,  and  by  the  bleaching  of  a  piece  of  moistened  logwood  paper 
introduced  into  the  tube.  Heated  with  carbonate  of  soda  upon  charcoal, 
they  yield  a  mass  which,  when  moistened,  blackens  silver  on  which  it  is 
laid,  and  evolves  sulphuretted  hydrogen  when  acted  npon  by  acids. — 
3.  By  nitric  acid,  and  still  more  easily  by  aqua  regia,  most  metallic 
sulphides  are  resolved  into  oxide,  sulpnur,  and  sulphuric  acid :  fuming 
nitric  acid  acts  on  them  with  peculiar  violence,  sometimes  with  evolution 
of  light  and  heat.  Hypochlorous  acid  and  its  salts  likewise  produce  me- 
tallic oxide  and  sulphuric  acid. — 4.  Chlorine  acts  upon  many  metallic 
sulphides,  sometimes  even  at  ordinary  temperatures,  in  such  a  manner  as 
to  form  chloride  of  sulphur  and  a  metallic  chloride. — 5.  Hydrated  acids, 
even  dilute  nitric  acid,  resolve  many  metallic  sulphides  into  hydro- 
sulphuric  acid  and  a  salt.  In  the  case  of  a  hydrogen-acid,  the  action 
takes  plase  thus : 

8bS»  +  3HC1  =  SbW  -|-  3HS: 
in  that  of  an  oxygen-acid,  we  have  for  example : 

CaS  +  80»  4-  HO  =  CaO,  SO'  +  HS. 
Warm  concentrated  hydrochloric  acid  decomposes  in  this  manner,  even 
the  tersulphide  of  antimony,  the  sesqui-sulphide  of  bismuth,  and  theproto- 
Bulphides  of  cadmium,  lead,  and  tin.  Hydrochloric  acid  gas  acts  upon 
most  metallic  sulphides  so  as  to  form  hydrosulphuric  acid  and  a  metallic 
chloride  :  sometimes  the  aid  of  heat  is  required. — 6.  Alkalis,  both  in  the 
dry  and  in  the  moist  way,  decompose  many  heavy  metallic  sulphides, 
the  products  of  the  decomposition  being  a  sulphide  of  the  alkali-metal 
and  a  heavy  metallic  oxide,  which  often  enter  into  new  combinations. — 
7.  Hydrogen  gas  at  a  red  heat  only,  decomposes  the  sulphides  of  anti- 
mony, bismuth,  tin,  copper,  and  silver,  into  hydrosulphuric  acid  and 
metal.  (H.  Rose,  Fogg.  4,  109.) — 8.  Charcoal  at  an  intense  red  heat,  robs 
certain  metallic  sulphides  of  part  or  the  whole  of  their  sulphur,  and  forms 
bi-sulphide  of  carbon. 

Most  heavy  metallic  sulphides  remain  unaltered  in  water.  Only  the 
sulphides  of  molybdenum,  tungsten,  and  arsenic  are,  when  finely  divided, 
slightly  soluble  in  water,  and  are  precipitated  from  it  by  acids,  even  by 
hydrosulphuric  acid.  (Berzelius.)  When  vapour  of  water  is  passed  over 
metallic  sulphides  at  a  strong  red  heat,  they  are  often  resolved  into  hy- 
drosulphuric acid  and  a  metallic  oxide,  the  latter  of  which  often  acts  npon 
the  rest  of  the  sulphide  in  such  a  manner  as  to  form  reduced  metal  and 
sulphurous  acid.  (Ilegnault.)  Sulphide  of  aluminum  and  sulphide  of  sili- 
cium  in  contact  with  water  at  ordinary  temperatures  produce  hydrosul- 


METALLIC  SULPHIDES.  225 

^1  phuric  acid  and  metallic  oxide.     The  sulphides  of  barium,  strontium,  and 

calcium,  are  resolyed  with  water  into  alkali>  which,  on  account  of  its 
sparing  solubility,  crystallizes  out  first,  and  a  hydrated  double  sulphide  of 
^^  the  metal  and  hydrogen  {gewdKertea  Hydrothvm-SckwefdmetaiC)^  or,  what 

^  comes  to  the  same  thing,  a  bi-hydrosulphate  of  the  alkali.     When  the 

^  protosulphides  of  potassium  and  sodium  are  brought  in  contact  with  a 

^  small  quantity  of  water,  great  heat  is  evolved,  and  an  oily  or  a  crystalline 

^  compound  formed,  which  is  soluble  in  a  larger  quantity  of  water.     The 

'^'  solution  may  be  regarded  as  containing  either  a  hydrated  protosulphide  of 

^  the  metal,  or  a  simple  hydrosulphate  of  the  alkali,  or  perhaps  also  as  a 

^  mixture  of  free  alkali  with  a  double  sulphide  of  the  metal  and  hydrogen 

^  (or  bi-hydrosulphate  of  the  alkali).    Pentasulphide  of  potassium  or  sodium 

^^  dissolves  in  water,  with  production  of  cold,  and  forms  a  solution  contain- 

^  ing  either  a  hydrated  metallic  pentasulphide,  or  an  alkaline  hydrosul- 

>/  phite. 

'-f  Compounds  of  Metallic  Sulphides  with  water,  which  may  also  be 

]^  regarded  as  salts  of  Hydrosul/phuric  acid,  ffydnmUphate$,  or  SuJ^y- 

»  draieg, 

a,  Hydrosulphates  of  the  Alkalis,  including  Ammonia. 
'  a  Simple  Alkaline  HydrotulphaJtes  or  Hydrated  Metallic  Protoml- 

\  phidee. 

These  compounds  are  obtained : — 1 .  By  bringing  the  protosulphides 
in  contact  with  water :  e.  g,  KS  -f  HO  =  KO,  HS. — 2.  By  passing  hydro- 
sulphuric  acid  gas  through  water  in  which  the  base  is  dissolved  or  diffused. 
/  According  to  the  experiments  of  H.  Rose,  the  existence  of  the  simple 

hydrosulphates  of  baryta,  strontia,  or  lime,  is  doubtful.     On  saturating 
\  the  liquid  with  hydrosulphurio  acid,  each  atom  of  base  takes  up  2  atoms 

of  that  acid,  and  there  is  formed,  according  to  one  theory,  a  double  sul- 
phide of  the  metal  and  hydrogen : 

KO  +  2HS=:  KS,HS  +  HO; 
or,  according  to  the  other  view,  a  bi-hydrosulphate  of  the  alkali,  viz., 
K0,2HS.  By  the  addition  of  a  fresh  quantity  of  the  base  equal  to  that 
used  in  the  first  instance,  this  compound  may  be  converted  into  pure 
hydrated  metallic  sulphide,  or  into  a  simple  hydrosulphate  of  the 
alkali. 

The  alkaline  hydrosulphates  are  either  crystalline  or  oily,  colourless, 
soluble  in  water,  strongly  alkaline,  corrosive,  have  a  sharp  and  bitter 
taste,  and  smell  of  hydrosulphurio  acid,  inasmuch  as  that  gas  is  slowly 
evolved  from  them  by  the  action  of  carbonic  acid  contained  in  the  air. 
Hydrosulphate  of  ammonia  yolatilizes  when  heated;  the  other  alkaline 
hydrosulphates,  heated  out  of  contact  of  air,  either  leave  a  protosulphide 
of  the  metal  (potassa),  or  evolve  hydrosulphurio  acid  and  leave  alkali 
(lime).  Their  aqueous  solution  boiled  witn  sulphur  takes  up  4  atoms 
more  of  that  substance,  and  is  converted  into  solution  of  metallic  penta- 
sulphide or  of  alkaline  hydrosulphite : 

KS  +  4S  =  KS»;  or  KO,HS  +  48  =  K0,HS>. 

By  exposure  to  the  air,  the  dissolyed  compounds  are  gradually  oxidated ; 

at  first  assuming  a  yellow  colour,  and  being  converted  into  metallic  pen- 

tasulphides  or  alkaline  hydrosulphites,  with  excess  of  alkali. 

5K8  +  40  =  K8»  +  4KO; 

or:  5(KO,H8)  +  40  =  KO,H8«  +  4K0  +  4H0. 

This  compound  is  converted  by  further  oxidation  into  an  alkaline  hypo- 
sulphite, then  into  sulphite,  and  finally  into  sulphate. 

VOL.  II.  ^ 


226  SULPHUK. 

KS»  +  4K0  +  160  =  5  (KO,  S0».) 
The  alkaline  hyposulphite  is  qoicklj  formed  by  boiling  the  solution  in 
the  air,  especially  if  an  alkaline  carbonate  be  present.  This  explains  the 
occurrence  of  alkaline  hyposulphites  in  hepatic  mineral  waters  after 
they  have  been  boiled  down.  (Fuchs,  Kastn.  Arch,  7>  1 01 ;  L.  A.  Buchner, 
Bepert.  61, 19.)  Water  containing  air  acts  in  the  same  manner  by  virtue 
of  the  oxygen  which  it  has  absorbed,  but  the  action  is  slow  at  ordinary 
temperatures.  If  sulphide  of  sodium  is  dissolyed  in  water  containing  air, 
and  filtered  after  half  an  hour  through  acetate  of  lead,  the  liquid  on  being 
boiled  yields  a  gaseous  mixture,  containing  26*6  per  cent,  of  oxygen  :  if 
the  precipitation  be  deferred  for  4  hours,  the  gaseous  mixture  then  evolyed 
still  conUiins  6  per  cent,  of  oxygen ;  and  if  the  water  has  a  temperature 
of  87'5^  and  the  precipitation  is  performed  after  half  an  hour,  the  gaseous 
mixture  is  found  to  contain  only  4*8  per  cent,  of  oxygen.  ^Anglada^ 
Ann.  Chim.  Fhys.  20,  260.)  Small  quantities  of  sulphurous  acid  cause  a 
precipitation  of  sulphur,  and  produce  a  mixture  of  alkaline  hyposulphite 
and  hydrosnlphite :  with  larger  quantities,  the  former  salt  only  is  pro- 
duced. Black  oxide  of  manganese  acts  in  a  similar  manner  by  virtue  of 
the  oxygen  which  it  contains.  A  small  quantity  of  chlorine  produces  a 
chloride  and  pentasulphide  of  the  metal,  or  a  hydrochlorate  ana  hydrosnl- 
phite of  the  alkali :  e.  g, 

6KS  +  4a  =  4KC1  +  KS» 
or:  5(K0,HS)  +  40  ==  4(KO,HCl)  +  KO,  HS^ 

Excess  of  chlorine  decomposes  the  water,  the  hydrogen  of  which  it  takes 
up,  and,  in  the  case  of  potassa  and  soda,  produces  a  metallic  chloride  and 
an  alkaline  bisulphate : 

2K8  +  7H0  +  Sa  =  KO«2SO'  +  KCl  +  7Ha. 
Acids  added  in  small  quantity,  eyen  the  weakest,  such  as  carbonic  acid 
— ^proyided  they  do  not  bring  about  another  decomposition  by  oxidation — 
convert  the  simple  alkaline  hydrosulphates  into  bi-hydrosulphates ;  and, 
when  added  in  larger  quantity,  expel  the  whole  of  the  hydrosulphuric  acid 
from  the  latter. 

P,  Bi-hydrosulpliates  of  the  A  Ikalis,  including  magnesia  and  ammo- 
nia, or  Hydrated  Dotible  Sulphides  of  Hydrogen  and  the  AlkalirmeUdi  : 
called  Sul/hydrates  by  Berzelius,  Sulfhydrurets  by  Rose. 

These  compounds  are  obtained:  1.  By  bringmg  a  double  sulphide  of 
hydrogen  and  an  alkali-metal  in  contact  with  water. — 2.  By  passing 
h^droffulphuric  acid  gas  to  saturation  through  water  in  which  the  base  is 
dissolyed  or  diffused  (p.  225).  They  are  colourless,  and  mostly  crystalli»- 
able.  When  heated  out  of  contact  of  air,  they  either  sublime  (ammonia), 
or  leaye  the  corresponding  anhydrous  double  sulphides  (potassa^  soda, 
lithia); 

K0,2HS»KS,HS  +  HO; 

or  theyeyolye  hydrosulphuric  acid,  and  leaye  metallic  oxide.  (The  earthy 
alkalis  and  magnesia.)  When  dissolyed  in  water,  they  are  conyerted,  by 
boiling  with  sulphur,  into  hydrated  metallic  pentasulphides  or  alkaline 
hydrosulphitos,  the  change  being  attended  with  the  eyolution  of  half 
their  hydrosulphuric  acid.  They  also  giye  up  half  their  hydrosulphuric 
acid,  when  they  form  precipitates  with  solutions  of  the  normal  sulphate  of 
protoxide  of  manganese,  or  of  iron,  or  with  sulphate  of  zinc.  By  this 
character  thej  are  distinguished  from  the  simple  alkaline  hydrosulphates, 
which  precipitate  the  sulphates  just  mentioned — ^proyided  no  excess  of  acid 
is  present-^without  emitting  an  odour  of  sulphuretted  hydrogen.    AU 


1^ 


METALLIC  SULPHIDES.  227 

acids  expel  the  hydroeulphurie  acid  contained  in  these  salts.     Between 
h  carbonic  acid  and  hydrosnlphuric  acid,  reciprocal  affinity  comes  into  play. 

he  (I.;  126.)     When  carbonic  acid  gas  is  passed  through  the  solation  of  an 

jer  alkaline  hydrosalphate,  a  bicarbonate  is  formed,  and  all  the  hydrosnlphu* 

sr,  ric  acid  padually  driven  out.     From  a  solation  of  bi-hydrosolphate  of 

ae  lime,  carbonic  acid  Uberatee  the  hydrosnlphuric  acid,  and  precipitates 

ij  neutral  carbonate  of  lime,  which  is  aiterwaids  converted  into  bicarbonate 

ir,  and  dissolved.  (L.  A.  Buchner.)     If,  on  the  other  hand,  hydrosnlphuric 

^  acid  gas  be  passed  through  water  in  which  bicarbonate  of  ammonia^ 

j[  potasn,  soda,  baryta,  strontia^  lime,  or  mafueeia,  is  dissolved  or  diffused, 

^  an  alkaline  bi-hydrosulphate  is  at  first  produced,  together  with  a  bicarbo- 

jf  nate ;  the  latter  mAj,  however,  be  completely  decomposed  by  passing  the 

gas  through  the  liquid  for  a  considerable  time.  The  quantity  of  hydrosnl- 
phuric acid  gas  required  to  decompose  a  carbonate  completely,  is  greater 

1  than  the  quantity  of  carbonic  acid  gas  required  to  decompose  a  hydrosul- 

2  phate.  In  both  cases,  a  large  excess  of  the  decomposinff  acid  is  necessary; 
^  for  the  adhesion  of  the  one  sas  to  the  other  is  one  of  the  forces  by  which 
f  the  decomposition  is  effected.  When  an  aqueous  solution  of  1  At.  baryta 
^                      or  lime  is  brought  in  contact  with  a  mixture  of  1  At.  carbonic  acid  and 

1  At.  hydrosnlphuric  acid  ffas,  neutral  carbonate  of  baryta  or  lime  is  pre- 
cipitated, and  the  water  dissolves  bicarbonate  and  bi-hydrosulphate  of 
baryta  or  lime.  The  mater  the  excess  of  either  gas,  the  larger  is  the 
quantity  of  the  corresponding  salt  produced.  Hence  it  may  be  concluded 
tnat  all  sulphuretted  waters  which  contain  an  alkaline  carbonate  with 
excess  of  carbonic  acid,  do  not  contain  all  their  hydrosnlphuric  acid  in 
I  the  free  state,  but  a  small  portion  in  the  form  of  an  alkaline  bi-hydrosul- 

phate. (Fuchs,  Kcutn.  Arch.  7.  101;  O.  Henry,  «7.  Chim.  Med.  1,  257 
and  320;  Gay-Lussac,  Ann.  Ghim,  Fhys.  30,  291;  also  N.  Tr.  12,  2, 
260;  L.  A.  Buchner,  Eepert,  61,  19.)  The  statement  of  Vauquelin 
(</.  Fharm,  11,  124)  and  0.  Henry,  that  bicarbonate  of  lime  or  baryta  is 
not  decomposed  by  hydrosnlphuric  acid,  is  disproved  by  L.  A.  Buchner : 
the  deeomposition  is,  however,  veiy  slow. 

h,  Bydrasulphatei  of  the  Heavy  Metallic  Oxides. 

When  a  salt  of  protoxide  of  manganese,  oxide  of  zinc,  protoxide  or 
binoxide  of  tin,  protoxide  or  sesqui-oxide  of  iron,  protoxide  of  cobalt,  or 
oxide  of  nickel,  is  precipitated  by  the  aaueous  solution  of  a  simple  hydro- 
sulphate  or  bi-hydrosulphate  of  an  iJkaii,  the  precipitate  (the  formation 
of  which,  in  the  case  of  a  nickel-salt,  is  attendea  with  evolution  of  sulphu- 
retted hydroeen)  consists,  not  of  anhydrous  metallic  sulphide,  but  of  a 
compound  which  may  be  regarded  either  as  a  hydrated  sulphide  of  the 
metal,  or  as  a  hydrosulphate  of  the  oxide.  In  the  case  of  protoxide  of 
iron,  it  is  FeS  +  HO  or  FeO,HS;  with  the  sesqui-oxide,  Fe*^  +  3H0  or 
FeW  +  3HS;  with  protoxide  of  tin,  SnS  +  HO,  orSnO,HS;  with  bin- 
oxide  of  tin ;  SnS*  +  2H0  or  SnO*  H-  2HS.  These  precipitates  often  differ 
greatly  in  colour  from  the  corresponding  anhydrous  sulphides;  e.a.  MnS 
IS  dark  green ;  MnS  +  HO,  flesh-colour^  They  are  tasteless  and  inodo- 
rous. Heated  out  of  contact  of  air,  they  evolve  water,  and  leave  anhy- 
drous metallic  sulphide.  By  exposure  to  the  air  at  ordinary  temperatures, 
many  of  them,  that  of  iron  for  example,  are  oxidised  and  converted  either 
into  a  mixture  of  oxide  and  sulphur,  or  into  a  compound  of  the  oxide  with 
sulphuric  acid.  When  digestea  with  any  of  the  stronger  acids,  all  of  them, 
excepting  the  hydrated  bisulphide  of  tin,  evolve  hydrosnlphuric  acid. 
They  are  insoluble  in  water. 

Q  2 


228  SULPHUR. 

c.  EydnUed  MetaUic  Pentasulphides,  or  Salts  of  Hydrosulphurous 
acid,  ffydrondphttes,  Compounds  of  Perstdphide  of  Hydrogen,  Stdfures 
hydrpghiH,  HydrosvXfures  sulfuris,  Hydrosulfates  svlfuris.  fFor  the  for- 
mation and  preparation  of  these  compounds,  vid.  p.  193.]  Tlie  alkaline 
hjdrosolpbites  are  the  only  salts  of  this  class  that  have  been  formed:  the 
ammonia-<M>mponnd  has  been  obtained  in  the  crystalline  state,  the  others 
only  in  the  state  of  aoneons  solution. 

Red-brown,  or  when  considerably  diluted,  ortnge-yellow  liquids — 
smelling  slightly  of  hydrosulphuric  acid — ^baring  a  caustic,  alkaline,  and 
somewhat  bitter  taste,  alkaline  reaction,  and  corrosive  properties. 

The  solution  becomes  colourless  by  exposure  to  the  air,  a  hyposulphite 
being  formed  and  sulphur  precipitated  at  the  same  time : 

KS»  +  30  =  KO,S«0«3S 
or:  KO,HS»  +  30  =  KO,  S«0«  +  3S  +  HO; 

hence  the  liquid  is  rendered  turbid  by  mixture  with  aerated  water.  If, 
however,  the  solution  contains  free  alkali,  no  sulphur  is  precipitated,  and 
the  hyposulphite  first  formed  is  converted  into  sulphite,  and  ultimately  into 
sulphate  (Gtiy-Lussac  &  Welter) : 

KS»  +  4KO  +  160  =  5(K0,  SO».) 
Sulphurous  acid  and  alkaline  sulphites  give  rise  to  the  formation  of 
hyposulphites,  with  precipitation  of  sulphur.  Peroxide  of  manganese  pro- 
duces a  similar  action.  Nitric  acid  in  excess  takes  up  the  alkali,  oxidates 
the  hydrogen  of  the  hydrosulphurous  acid,  and  precipitates  the  sulphur. 
Other  aciduB,  such  as  hydrochloric  or  sulphuric  acid,  which  do  not  giye  up 
oxygen,  separate  the  hydrosulphurous  acid  in  its  own  proper  form,  pro- 
yid^  they  are  made  to  act  at  once  in  large  excess;  but  if  they  are  added 
to  the  solution  in  successive  small  portions,  the  undecomposed  portion  of 
the  hydrosulphite  exerts  an  instantaneous  decomposing  action  on  the  sepa- 
rated hydrosulphurous  acid  (p.  193),  so  that  sulphuretted  hydrogen  gas 
is  evolved  and  one  atom  of  sulphur  precipitated.  Hydrosulphuric  acid  gas 
passed  through  the  solution  precipitates  tour  atoms  of  sulphur,  and  produces 
an  alkaline  bi-hydrosulphate.  Mercury,  silver,  and  other  metals,  withdraw 
four  atoms  of  sulphur  from  the  solution,  so  that  a  hydrated  protosulphide 
of  the  metal  or  a  simple  hydrosulphate  of  the  alkali  is  left  behind. 

Compounds  of  Metallic  Sulphides  with  Bisulphide  of  Carbon.  SvU 
pho-carhonates  of  Berzelius.  In  combination  with  water  they  may  like- 
wise be  regarded  as  Hydro-sulphocarhonates,  The  potassium-compound, 
for  example,  is  KS,  CS',  or  KCS* :  if  one  atom  of  water  be  added  to  it, 
the  resulting  compound  may  be  considered  as :  KG,  CS^  HS  =  KO,  HCS'. 

Preparation,  1 .  The  hydrated  protosulphide  of  an  alkali-metal  (or 
simple  alkaline  hydrosulphate)  is  brought  in  contact  with  bi-sulphide  of 
earbon  in  a  close  vessel  at  a  temperature  of  30°:  the  sulphide  of  carbon 
quickly  dissolves,  forming  a  brown  solution.  (Berzelius.)  Aqueous  solu- 
tions of  the  fixed  alkalis  yield  the  same  compounds  with  bisulphide  of 
carbon ;  but  the  action  is  slower,  and  the  product  is  mixed  with  alkaline 
carbonate.  Solution  of  ammonia  gives  a  mixture  of  hy  dro-sulphocarbonate 
and  sulph-hydrocyanate  of  ammonia.  (Zeise,  p.  204.)  Aqueous  solutions 
of  double  sulphides  of  metals  and  hydrogen,  or  of  metallic  pentasulphides 
do  not  dissolve  bisulphide  of  carbon.  (Berzelius.) — 2.  Hydro-sulphocar- 
bonic  acid  is  mixed  with  a  caustic  alkali  or  an  alKallne  carbonate.  Car- 
bonic acid  is  then  evolved.     By  eyaporating  certain  solutions  obtained  by 


I 


METALLIC  SULPHIDES.  229 

'fkn  (^)  or  (2V  at  temperatures  below  40^^  the  anhydrous  oompounds  of  bisul- 

^  phide  ot  carbon  with  the  metaUic  sulphides  are  obtained. — 3.  Solu- 

^k  tions  of  heayy  metallic  salts  are  precipitated  by  hydro-sulphocarbonate  of 

ilUit  ammonia  or  potassa.     Oxide  of  copper  digested  in  aqueous  solution  of 

^;  k  hydro-sulphocarbonate  of  lime^  is  converted  into  double  sulphide  of  car- 

iqiIb!  bon  and  copper,  with  precipitation  of  lime. 

The  anhydrous  compounds  are  reddish-yellow,  brownish-yellow,  brown, 
gj^  or  black;   the  hydrated  compounds  yellow.     Those  which  are  soluble 

« uj  have  a  taste  which  is  first  cooling,  then  peppery,  and  afterwards  hepatic. 

(Berzelius.) 
L^  The  potassium-compound  heated  out  of  contact  of  air  is  resolred  into 

^  charcoal  and  metallic  tersulphide  (KS,  OS'  =  KS^  -{-  C) ;  the  Wium, 

strontium,  and  calcium  compounds,  and  those  of  the  heayy  metals,  evolye 
sulphide  of  carbon  and  leave  metallio  sulphide — ^the  decomposition  taking 
place,  sometimes  at  ordinary,   sometimes  at  higher  temperatures  (PbS, 
^  CS'  =  PbS  +  CS').     If  water  is  present,  the  action  of  heat  gives  rise  to 

f^  the   formation  of  a  variety  of  products,  such  as  carbonic,  sulphurous, 

^  and  hvdrosulphuric  acid,  and  sulphur.     The  solutions  of  the  alkali-com« 

pounds  are  resolved  by  boiling  into  alkaline  carbonate  and  hydrosulphnric 
acid  gas: 
i  KS,C8«  +  3HO  =  KO,CO*  +  3H8. 

^  The  compounds  of  the  alkalis  and  some  of  the  earths  are  soluble  in 

*  water.     These  solutions,  when  concentrated,  are  tolerably  permanent  in  the 

air;  but  in  the  dilute  state  they  are  rapidly  decomposed,  sulphur  being 
?  precipitated  and  a  carbonate  formed. 

i  KS,CS*  +  30  =  KO,  CO«  +  3S: 

f  or:  KO,HCS»  +  30  =  KO,CO«  +  HO  +  3S. 

The  concentrated  solution  mixed  with  one  of  the  stronger  acids  forms  a 
yellow  milky  substance,  from  which  hydrosulphocarbonic  acid  fi;radually 
separates  in  the  form  of  an  oily  liquid.  Those  compounds  which  are  not 
of  themselves  soluble  in  water  are  rendered  soluble  by  mixture  with  an 
alkali-compound.  (Berzelius.)  The  solutions  of  the  alkali-compounds 
give  a  yellowish-white  precipitate  with  zino-salts,  lemon-yellow  with  cad- 
mium-mts  (Berzelius),  red  with  lead-salts,  brown  with  copper-salts,  and 
yellow  with  salts  of  mercuric  oxide.  The  last  two  precipitates  turn  black 
m  a  few  hours,  bisulphide  of  carbon  being  evolved  and  a  metallic  sulphide 
formed.  Silver  solutions  are  precipitated  yellow  when  dilute  (the  preci- 
pitate soon  turning  brown,  and  afterwards  black),  and  black  when  con- 
centrated. (Zeise.) 

Compounds  of  Metallio  Sulphides  one  with  another.  Metallic  Sul- 
phur-saUs. 

Metallic  sulphides  may  be  divided,  with  referenoe  to  their  relations 
one  to  another,  mto  basic  sulphides,  or  Stdphur-bases,  and  acid  sulphides, 
or  Stdphur-acids.  A  metal  which  forms  an  oxyeen-base  when  combined 
with  a  certain  number  of  atoms  of  oxygen,  produces  a  sulphur-base  by 
combination  with  an  equal  number  of  atoms  of  sulphur;  and  in  a  similar 
manner,  the  number  of  oxygen-atoms  in  a  metalbo  acid  agrees  with  the 
number  of  su]phur-«toms  in  the  corresponding  sulphur-acid.  Thus, 
KSyFeS,  Fe'S',Cu'S,CuS,  &c.,  are  sulphur-bases  corresponding  to  the  oxy- 
gen-bases KO,FeO,FeK)»,Cu«0,CuO;  andMoS»,ABS',  AsS»,TeS»,SnS«,&o., 
are  sulphur-acids  analogous  to  the  oxygen-acids  MoO^,  AsO^  AsO',TeO*i 


230  SULPHUR. 

SnO^,  &o.  In  the  sulphur  series^  however,  as  in  the  oxygen-eeries,  there 
is  a  gradual  transition  from  the  bases  to  the  acids;  and  the  sulphides 
which  stand  near  the  middle  of  the  series,  Fe%',  for  example,  play  the 
part  of  sulphur-acids  towards  those  which  are  more  strongly  basic,  and 
of  sulphur-bases  towards  those  which  are  more  strongly  acid  than 
themselves. 

Preparation  of  Stdphur-MUe.  1.  By  dissolving  the  sulphur-acid  in 
aqueous  solutions  of  sulphides  of  the  alkali-metals,  e.  g,  AsS'  in  KS : 
the  combination  is  often  attended  with  development  of  heat  Instead  of 
a  sulphide  of  the  alkali-metal,  a  double  sulphide  of  hvdrogen  and  the  metal 
may  be  used,  e,  g,  KS,  HS :  but  in  that  case,  hydrosulphuric  acid  is  evolved 
with  effervescence. — 2.  By  passing  hydrosulphuric  acid  gas  through  the 
solution  of  an  oxygen-salt  containing  a  metallic  acid,  or  by  heating  the 
latter  with  bi-hydrosulphate  of  ammonia,  till  the  excess  of  the  latter  and 
of  the  ammonia  set  free  in  the  process  is  driven  off.  By  the  action  of  the 
hydrosulphuric  acid,  water  is  formed,  the  metallic  oxide  converted  into  a 
sulphur-base,  and  the  acid  into  a  sulphur-acid : 

3KO,  AsO*  +  8HS  :=:  SKS^AiS'  +  6H0. 
3.  By  fusing  an  alkaline  carbonate  with  a  sulphur-acid.  The  carbonic 
acid  escapes ;  part  of  the  alkali  reacts  on  the  sulphur-acid  in  such  a  man- 
ner as  to  form  a  sulphide  of  the  alkali-metal  and  a  metallic  acid,  and  the 
result  is  a  mixture  of  oxygennEalt  and  sulphur-salt.— 4.  By  saturating  the 
aqueous  solution  of  a  caustic  alkali  or  an  alkaline  carbonate  with  a  sulphur- 
acid.  The  reaction  is  the  same  as  in  the  last  case. — 5.  By  bringing  a 
metallic  acid  in  contact  with  aqueous  solution  of  sulphide  of  hydrogen  and 
potassium.  The  quantity  of  hydrosulphuric  add  present  not  being  suffi- 
cient for  the  complete  conversion  of  the  metallic  acid  into  sulphide,  a  por- 
tion of  sulphide  of  potassium  is  likewise  decomposed,  and  consequently 
the  sulphur-salt  produced  is  mixed  with  a  potash-salt  of  the  metallic 
acid. — 6.  Sulphur-salts  having  a  sulphide  of  an  earth-metal  or  of  a  heavy 
metal  for  their  base,  are  obtained  by  precipitating  an  oxygen-saJt  of  an 
earth-metal  or  heavy  metal  by  a  sulphur-salt  of  potassium  or  other  alkali- 
metal. 

Most  sulphur-salts  are  decomposed  by  hydrated  oxygen-acids  and 
hydrogen-acids, — ^the  sulphur-base  being  converted,  with  evolution  of  sul- 
phuretted hydrogen,  into  a  compound  of  oxygen-acid  and  metallic  oxide, 
or  into  a  haloid-salt,  and  the  sulphur-acid  separated : 

3KS,AsS»  +  3S0»  +  3HO  =  3(KO,SO»)    +AiS»  +  3HS; 
similarly : 

3KS,AbS*  +  3HC1  =  3KC1  +  AbS»  +  3HS. 
But  if  the  sulphur-salt  has  been  prepared  by  method  3  or  4,  and  still 
remains  mixed  with  the  oxygen-sait  produced  at  the  same  time,  the  sul- 
phur^acid  is  precipitated  by  the  oxygen  or  hydrogen-acid,  just  as  in  any 
other  case ;  but  no  hydrosulphuric  acid  is  evolved,  because  the  metallic 
os^gen-acid  present  is  by  its  action  reconverted  into  sulphur-acid.  From 
this  mode  of  decomposition  it  might  be  inferred  that  the  sulphur-acid  was 
combined  with  the  alkali  in  its  own  proper  form,  and  not  as  a  mixture  of 
sulphur-salt  and  oxygen-salt :  but  the  presence  of  an  oxygen-salt  in  such 
solutions  may  be  demonstrated  by  digesting  them  with  hydrated  oxide  of 
copper;  for  the  oxide  of  copper  resolves  sulphide  of  potassium,  for  example, 
into  potash,  and  an  insoluble  sulphur-salt  having  sulphide  of  copper  for 
its  base,  while  the  filtrate  contains  the  metallic  acid  in  combination  with 
potash.  (Berzelius.) 


SELENIUM.  231 

Many  salphar-ealts  are  either  capable  of  combining  with  water  in 
definite  proportions,  or  soluble  in  it.  Sach  compoands  may  be  regarded 
either  as  hydrated  sulphnr-salts,  or  as  double  hjdrosulphates.  For 
instance,  Schlippes  salt  in  the  crystallized  state  is  either  SNaS,  SbS*  +  18 
Aq. :  or  3(NaO,HS)  +  SbO*,H»S»  +  10  Aq.  {vid.  p.  10,  2  and  3.) 

Many  metallic  sulphides  likewise  combine  with  oxides,  forming  com- 
pounds called  Oxymlphides;  also  with  iodides  and  chlorides. 

G.  Sulphur  likewise^  combines  with  seyeral  organic  substances;  e,  g. 
alcohol,  ether,  yolatile  oils,  fat,  resin,  &c.,  and  is  a  constituent  of  certain 
organic  compounds. 


Chapter  VII. 

SELENIUM, 


Bereelins.    Schw.  23,  309  and  430;  34,  79.    Pagg.  7,  242;  8,  423. 
Mitscherlich.    Seleuic  Acid.    Pogg.  9,  623. 

Muspratt.    Salts  of  Selenious  Acid.     Quart.  Joum,  of  Chem.  Soc  of 
London^  2,  52. 


SeUne,  SeUn, 

HitAory.  Selenium  was  discovered  in  1817  by  Berzelius,  who  thoroughly 
inyestigated  most  of  its  chemical  relations.  Wienie  acid  was  discoyered 
in  1827  by  Mitscherlich. 

Sources.  In  Riolite,  as  pure  selenium,  mixed  with  variable  quantities 
of  seleniferous  sulphur,  selenide  of  cadmium,  and  selenide  of  iron  (Del 
Rio,  PhU.  Mag.  J\  8,  261 ;  also  Pogg,  39,  526);  as  seleniferous  sulphur, 
in  Volcano,  one  of  the  Lipari  islands  (Stromeyer,  Pogg.  2,  410);  as  sele- 
nide of  l^ad  (Zinken  Sc  H.  Rose,  Pogg.  3,  271,  Kersten);  as  selenide  of 
copper  (Berzelius) ;  as  selenide  of  silver  (H.  Rose) ;  as  selenide  of  mercury 
(Del  Rio;  Tiemann  &  Marx,  Scho.  54,  224);  a  selenide  of  copper  and 
silver,  or  eukairite  (Berzelius) ;  as  selenide  of  copper  and  lead  (Selen- 
kupfer-blei  and  Selen-blei-kupfer.  H.  Pose,  Kertten) ;  as  selenide  of  cobalt 
and  lead  (Stromeyer,  Pogg,  2,  403);  as  selenide  of  mercury  and  lead 

SI.  Rose);  as  selenide  of  sulphur  and  mercuiy  (H.  Rose,  Pogg.  46,  315; 
ersten,  Kadn.  Arch.  14,  127);  as  selenite  of  lead  (Kersten,  Pogg.  46, 
265).  Moreover,  in  very  small  quantities:  in  iron  pyrites  from  Fahlun: 
seleniferous  sulphur  is  obtained  from  this  substance  by  distillation,  and 
used  at  Gripsholm  for  the  manufacture  of  English  oil  of  vitriol ;  a  seleni- 
ferous  deposit  is  formed  on  the  floor  of  the  leaden  chamber.  (Berzelius.) 
In  iron  pyrites  from  Kiaslitz  in  Bohemia  (Buch  &  Wbhler,  OHh.  69,  264) ; 
green  vitriol  ie  formed  from  this  substance,  and  used  in  the  prepa- 
ration of  fuming  oil  of  vitriol :  when  the  fuming  acid  thus  obtamed  is 
diluted  with  water,  a  precipitate  of  selenium  is  obtained.  (L.  Gmelin, 
OiJh.  65,  206.)  In  iron  pyrites  from  Luckawitz  in  Bohemia:  the  sulphur 
obtained  from  this  pjrites  yields,  when  used  in  the  preparation  of  English 
oil  of  vitriol,  a  seleniferous  deposit  on  the  floor  of  the  leaden  chamber, 
similar  to  that  yielded  by  the  Fahlun  sulphur,  and  containing,  according 


232  SELENIUM. 

to  Lewenau  {Ahhandl.  uber  das  SeUn.  Wien,  1823),  7' 8  per  cent,  of 
selenium  (Schiattenbach ;  Scholz,  &ckw,  38,  231 ;  Pleischl,  39,  348).  In 
the  pyrites  from  which  oil  of  vitriol  is  prepared  at  Nordhausen  and 
Bodenmais  (Buch,  N.  Tr.  3,  1,  435;  Miiller,  Br.  Arck,  2,  325;  H.  v. 
Meyer,  Kadn.  Arch.  6,  332).  In  iron  pyrites  from  Felsobanya,  Rota^ 
and  Kapnik  (Kersten,  Kastn.  Arch,  14, 133).  In  cojpper  pyrites  from  the 
Paris  mountain  in  the  isle  of  Anglesea^  and  in  the  oil  of  yitriol  prepared  from 
it.  (Edm.  Thomson,  Ann.  FhU,  18,  52.)  In  copper  pyrites  from  the 
Rammelsberg,  near  Goslar,  which  also  forms  a  seleniferous  deposit  on  the 
floor  of  the  leaden  chamber.  ^Sandorff  &  Otto,  Ann.  Pharm.  42,  345.)  In 
vitreous  copper  pitch-blende.  (Kersten.)  In  copper-bloom  from  Rheinbrei- 
tenbach^  but  not  in  that  obtained  from  other  localities.  (Kersten,  Schxo.  47, 
294;  further,  Fogg.  26, 492.)  In  uranium  pitch-blende!][from  Johanngeor- 
ffenstadt,  and  Schneeberg.  (Kersten,  Pogg.  26, 492.)  In  galena  from  Atwi- 
daberg  and  Fahlun.  ^erzelius.)  In  sulphide  of  molybdenum  from 
Schlackenwald.  (Pleischl.)     In  tellurium  ores.  (Berzelins,  Scholz.) 

PreparcUion.  1.  From  the  seleniferous  deposit  in  the  sulphuric  acid 
works  at  Gripsholm.  This  reddish  deposit  consists  of  selenium,  sulphur, 
arsenic,  zinc,  tin,  lead,  iron,  copper,  and  mercury.  It  is  dried  and  made 
up  with  aqua  regia  into  a  paste,  which  is  gently  warmed  till  it  begins  to 
give  out  the  odour  of  horse-radish,  and  then  mixed  with  more  aqua  regia. 
After  this,  it  is  left  to  itself  for  48  hours,  by  which  time  the  reddish  colour 
becomes  changed  to  the  greenish-yellow  of  impure  sulphur,  and  the  whole 
of  the  selenium  dissolves.  Water  is  then  added — the  oxide  of  lead  pre- 
cipitated by  sulphuric  acid — the  liquid  filtered — ^the  precipitate  washed 
for  a  considerable  time — ^the  dark-yellow  filtrate  mixed  with  the  wash- 
water — and  hydrosnlphuric  gas  passed  through  it, — ^whereby  a  mixture  of 
selenide  of  sulphur  with  the  sulphides  of  copper,  mercury,  tin,  and  arsenic 
is  precipitated,  and  iron  and  zinc  are  retained  in  solution.  The  dirty-yellow 
precipitate,  after  being  washed  and  pressed,  is  digested  in  concentrated  aqua 
regia,  till  the  undissolved  portion  has  assumed  the  yellow  colour  of  sul- 
phur; the  solution  is  decanted;  the  greater  part  of  the  excess  of  acid 
driven  off  by  evaporation ;  the  residue  (consisting  of  selenious  acid,  sul- 
phate of  copper,  cnloride  of  tin,  chloride  of  mercury,  and  a  small  quantity 
of  arsenic  acid),  mixed  with  small  portions  of  caustic  potash,  which  pre- 
cipitates the  oxides  of  copper,  tin,  and  mercury ;  the  alkaline  liquid  evapo- 
rated to  dryness ;  the  residue  ignited  in  a  platinum  crucible  to  expel  any 
remaining  trace  of  mercury,  then  quickly  pounded  in  a  warm  mortar,  and 
mixed  with  at  least  an  equal  weight  of  sal-ammoniac;  and  the  finely 
pounded  mixture  gradually  heated  in  a  glass  retort,  till  all  the  sal-ammo- 
niac is  volatilized,  or  even  to  a  higher  temperature  than  is  required  for 
that  purpose.  Part  of  the  selenium  is  carried  over  into  the  receiver 
together  with  the  water  and  ammonia  which  are  evolved ;  but  the  greater 
portion  sublimes  in  the  upper  part  of  the  retort;  or,  if  the  heat  applied  is 
not  very  great,  remains  behind  together  with  the  saline  mass  in  the  retort. 
This  saline  mass  is  dissolved  in  water,  the  selenium  well  washed  on  a  filter, 
and  distilled,  after  drying,  in  a  glass  retort.  (Berzelius.)  To  save  the 
small  quantities  of  selenium  contained  in  the  ammoniacal  distillate  above 
mentioned,  and  in  the  filtered  solution  of  the  saline  mass,  the  former  is 
heated  to  expel  the  ammonia,  then  mixed  with  the  latter,  and  the  whole 
boiled  with  repeated  additions  of  sulphurous  acid,  by  which  the  selenium 
is  precipitated.  If  the  mercury  has  not  been  completely  separated  in  the 
former  part  of  the  process,  it  is  precipitated,  together  with  the  selenium,  by 


SELENIUM.  233 

the  anlphnrons  acid.  If  the  arsenic  has  not  been  completely  precipitated 
bj  the  sulphuretted  hydrogen,  it  sublimes^  together  with  the  selenium^  on 
heating  the  mass  with  sal-ammoniac. 

2.  From  the  seleniferous  deposit  of  Lu<^awitz.  a.  This  substance  is 
dissolved  in  hot  caustic  potash,  and  the  liquid  filtered  and  exposed  to  the 
air  at  a  temperature  of  22®.  Hyposulpnite  of  potassa  is  formed  and 
selenium  precipitated  (the  quantity  amounting  to  llj^  per  cent,  of  the  de- 
posit). The  remainder  of  the  selenium  (\  per  cent.)  is  obtained  by  boiling 
the  mother-liquid  with  a  piece  of  sulphur.  A  trace  of  sulphur  perhaps 
remains  mixed  with  the  selenium.  Any  metallic  selenides  that  may  be 
contained  in  the  original  substance  are  not  dissolved  by  the  caustic 
potash.  ^Berzelius,  Fogg.  S,  423.)  Brunner  {Pogg,  81,  19)  first  distils 
the  seleniferous  deposit  in  a  glass  retort :  a  slightly  acid  watery  liquid 
passes  over,  at  the  commencement ;  then  a  dirty  yellow  selenide  of  sul- 
phur (amounting  to  12  per  cent,  oi  the  whole)  mixed  with  charcoal,  while 
a  black  powder  remains  behind. — a.  The  aistilled  selenide  of  sulphur 
coarsely  powdered  is  then  put  into  tolerably  strong  boiling  caustic  potash, 
in  sufficient  quantity  to  saturate  the  alksJi ;  the  solution  is  diluted  with 
six  times  its  bulk  of  water;  filtered,  in  case  of  any  deposition  of  sulphur, 
or  of  loosely  aggregated  charcoal  taking  place  after  long  standing;  and  the 
liquid  exposed  to  the  air  in  a  shallow  dish,  as  lon^  as  graphite-like  vegeta- 
tions form  in  it,  and  fall  in  scales  to  the  bottom.  Since  these  scales  may  still 
contain  sulphur,  they  are  again  dissolved  in  caustic  potash,  and  the  solu- 
tion exposed  to  the  air;'-or  they  are  dissolved  in  aqua  regia  ;  the  excess 
of  acid  expelled  by  evaporation;  the  liquid  diluted  with  water;  and  the 
selenium  precipitated  by  warming  with  sulphurous  acid.  After  the  de- 
position of  the  crystalline  scales,  the  first  alkaline  liquid  still  yields  sele- 
nide of  sulphur  in  scales  and  powder  of  a  fiery  red  colour,  and  containing 
from  10  to  12  per  cent,  of  selenium,  which  may  be  obtained  in  a  state  of 
purity  by  dissolving  the  selenide  of  sulphur  in  caustic  potash  and  ex- 
posing the  solution  to  the  air.  The  sulphur  which  separates  after  the 
lapse  of  several  weeks  from  the  first  alkaline  liquid,  likewise  contains 
selenium,  which  may  be  separated  in  the  same  manner.  At  length  the 
liquid  retains  but  a  trace  of  selenium,  which  may  be  separated  by  saturating 
with  hy<Irochloric  acid,  dissolving  the  resulting  precipitate  in  caustic 
potash,  and  exposing  the  liquid  to  the  air. — /9.  The  black  pulverulent  re- 
sidue in  the  retort,  consisting  of  quartz-sand,  lead,  iron,  lime,  alumina, 
charcoal,  sulphur,  and  a  trace  of  selenium,  is  heated  in  a  crucible  with  an 
equal  weight  of  nitre  and  three  times  its  weight  of  common  salt,  tiU  the 
black  colour  disappears ;  the  residue  is  then  exhausted  with  water.  The 
filtrate,  boiled  with  hydrochloric  acid  till  the  nitric  acid  is  expelled,  and 
then  digested  with  sulphite  of  ammonia,  yields  an  additional  quantity  of 
selenium.  100  parts  of  the  seleniferous  deposit  yield  6'1  parts  of  sele- 
nium by  a,  and  1*2  parts  by  /?,  making  together  7*3  parts  of  selenium. 
The  selenium  thus  obtained  is  finally  purified  by  distillation.  (Brunner.) — 
h.  The  seleniferous  deposit  is  heated  in  a  tubulated  retort  with  nitric 
acid,  the  acid  which  distils  over  being  frequently  poured  back,  and  the 
distillation  ultimately  carried  to  dryness.  The  residue  is  then  exhausted 
with  boiling  water — ^the  liquid  filtered — and  the  filtrate,  after  evaporation, 
mixed  with  sulphite  of  ammonia,  which  causes  a  precipitation  of  selenium. 
The  precipitate,  after  being  washed,  first  with  cold  and  then  with  hot 
water,  is  dried  and  completely  purified  by  distillation  in  a  glass  retort. 
(Scholz.)  Similar  to  this  is  the  method  of  Lewenau.  (Schw.  47>  306.) 
According  to    Berzelius,  however,    both   in    this  method   and  in    that 


234  SELENIUM. 

of  Scholx,  certain  metals,  mercury,  for  example,  may  be  i^recipitated 
together  with  the  selenium. — c.  The  dried  seleniferooa  deposit  is  intro- 
duced into  a  porcelain  tube,  and  heated  in  a  stream  of  diy  chlorine  gas, 
the  heat  beinff  regulated  so  as  not  to  allow  the  mass  to  fuse.  The  Tapoors 
of  chloride  of  selenium  and  chloride  of  sulphur  thereby  evolved  are  re- 
ceived in  a  vessel  containing  water,  attached  to  the  further  end  of  the 
tube;  and  the  liquid,  after  being  filtered  from  the  deposited  seleniferone 
sulphur,  is  mixed  with  sulphite  of  potassa  to  precipitate  the  selenium. 
By  this  method,  first  applied  by  H.  Rose  to  the  analysis  of  seleniferoos 
mmerals,  the  author  has  obtained  pure  selenium.—^.  If  the  seleniferoos 
deposit  is  rich  in  sulphur  and  poor  in  selenium,  Magnus  (Pogg,  20,  165) 
mixes  it  with  eight  times  its  weight  of  peroxide  of  manganese  and  heats 
the  mixture  to  redness  in  a  glass  retort.  The  sulphur  escapes  as  sulphnrooB 
acid — ^the  selenium  sublimes,  partly  in  the  free  state,  mixed  however  at  the 
beginning  with  a  little  sulphur— piurtly  in  the  form  of  selenious  acid.  The 
sulphurous  acid  gas  is  passed  through  water,  and  the  selenious  acid  carried 
over  with  it  is  thereby  reduced.  The  sublimed  selenium  is  freed  from 
sulphur  by  a  second  distillation  with  peroxide  of  manganese,  or  by  eola- 
tion in  caustic  potash  and  exposure  to  the  air,  or  by  solution  in  aquaregia 
and  precipitation  with  sulphurous  acid.— e.  The  seleniferous  deposit  or 
seleniferous  sulphur  may  likewise  be  burned  by  means  of  an  aspirator. 
The  sulphur  is  then  converted  into  sulphurous  acid,  while  selenium  con- 
taining but  little  sulphur  sublimes :  it  may  be  purified  by  solution  in 
potash.  (Brunner.) 

3.  From  Selenide  of  Lead. — a.  The  pounded  ore  is  freed  by  diges- 
tion in  dilute  hydrochloric  acid  from  calcspar  and  carbonate  of  iron,  which 
may  be  mixed  with  it;  then,  after  being  washed  and  dried,  it  is  intimately 
mixed  with  an  equal  weight  of  burnt  tartar;  and  the  mixture,  covered  with 
coarse  charcoal-powder,  is  ignited  for  an  hour  in  an  earthen  crucible  at 
a  moderate  heat.  The  mass,  after  cooling,  is  quickly  pounded  in  a  wann 
mortar— the  powder  thrown  on  a  filter,  and  washed  with  boiling  water 
thoroughly  freed  from  air,  the  washing  beiug  continued  as  long  as  the 
water  which  runs  through  exhibits  any  colonjr.  The  filter  must  all  the 
while  be  kept  quite  fuU  of  water,  to  prevent  the  selenide  of  potassium 
from  coming  in  contact  with  the  air.  The  red-brown  filtrate,  exposed  to 
the  air  in  shallow  dishes,  becomes  covered  with  a  reddish-black  crust  of 
selenium :  this  crust  must  be  frequently  broken  up  till  it  no  longer  forms 
and  the  liquid  becomes  colourless.  The  precipitated  selenium  is  waited 
on  a  filter,  and  freed  by  distillation  from  a  small  quantity  of  metallic  sele- 
nide which  may  be  mixed  with  it.  The  trace  of  selenium  which  remains 
dissolved  in  the  alkaline  liquid  may  be  separated  by  wanning  the  liquid 
with  hydrochloric  acid  and  sulphurous  acid.  From  the  powdered  ore 
which  remains  on  the  first  filter,  a  quantity  of  silver  may  be  obtained 
amounting  to  20  per  cent,  of  the  selenide  of  lead.  (W5hler,  Ann.  Pharm. 
41,  122.)  To  detect  traces  of  selenium  in  sulphur,  galena,  or  iron  pyrites, 
the  substance  may  be  fused  with  potash,  the  fused  mass  digested  in  water, 
and  the  filtered  solution  exposed  to  the  air:  selenium,  if  present,  will  then 
be  precipitated.  (Wehrle,  Zeitzsckr,  Phy$.  v.  W.  8,  817.)— 6.  Native 
selenide  of  lead,  pounded  and  freed  from  carbonates  by  digestion  in  hydro- 
chloric acid,  is  mixed  with  an  equal  weight  of  nitrate  of  soda,  and  the 
mixture  thrown  by  successive  portions  into  a  red-hot  crucible.  The  fused 
mass  when  cold  is  boiled  with  water ;  the  insoluble  residue,  which  con- 
tains no  more  selenium,  separated  by  filtration ;  and  the  solution  contain- 
ing seleniate,  nitrate,  and  nitrite  of  soda,  rapidly  boiled  down,  nitric  acid 


SELENIUM.  235 

being  added  to  decoinpoBe  the  nitrite :  crystals  of  anhydrous  seleniate  of 
soda  are  then  deposited.  The  liquid  poured  off  from  the  ciystals  while 
still  hot  deposits  nitrate  of  soda  on  cooling;  and  if  the  solution  poured  off 
from  this  oe  once  more  boiled  down,  it  again  yields  seleniate  of  soda. 
The  liquid  once  more  decanted  off  from  the  crystab  yields  a  fresh  portion 
of  nitrate  of  soda^ — and  so  on,  till  all  the  liquid  is  used  up.  The  seleniate 
of  soda  thus  obtuned  (slightly  contaminated  with  sulphate)  is  mixed  with 
sal-ammoniac  and  heated ;  and  when  the  mass  is  exhausted  with  water, 
pure  selenium  remains  behind.  (Mitscherlich.) 

4.  From  metallic  selenides  in  general.  Solution  of  selenic  add  is 
prepared  from  these  compounds,  ana  saturated  with  potash ;  the  residue 
obtained  by  evaporation  is  then  mixed  with  an  equal  weight  of  sal* 
ammoniac,  and  the  selenium  sublimed  in  a  ^lass  retort.  ^Berzeuns.) 

5.  From  the  Kraslitz  oil  of  vitriol.  This  liquid  is  diluted  with  twice 
its  bulk  of  water;  the  red  precipitate  freed  from  sulphuric  acid  b^  decan- 
tation  and  washing,  and  then  dried;  the  selenium  is  obtained  from  it  by  dis- 
tillation. A  small  quantity  of  inflammable  oil  is  evolved  in  this  process, 
and  the  black  residue  contains  a  lead  compound,  together  with  charcoal. 
The  red  precipitate  contains  a  considerable  quantity  of  gypsum,  from 
which  it  must  be  freed  by  repeated  washing  in  water.  100  parts  of  Bo- 
hemian oil  of  vitriol  yield  only  from  0*005  to  0*007  of  selenium.  (Joss, 
Schw.  69,  333.) 

Properties.  Selenium  crystallizes  in  four-sided  prisms.  From  an 
aqueous  solution  of  hydroseleniate  of  ammonia  exposed  to  the  air, 
Berzelius  obtained  selenium  in  square  prisms;  Frobel  {Pogg.  49,  590) 
obtained  it  in  rhombic  prisms  having  their  summits  and  lateral  edges 
truncated,  and  apparently  belonging  to  the  ri^ht  prismatic  system.  By 
sublimation,  or  by  cooling  a  saturated  solution  of  selenium  in  oil  of 
vitriol,  Frankenheim  {J,  pr.  Chem,  16, 13)  obtained  prisms  which  appeared 
to  be  obliquely  rhombia  Pleischl  {Kastn.  Arch.  4,  343)  obtained  by  sub- 
limation, acute  crystids  like  those  of  sulphur;  but  as  Berzelius  {Pogg, 
7,242),  found  that  the  crystab  which  he  himself  obtained  by  sublimation 
were  really  selenide  of  mercury,  he  suspects  that  something  similar  was 
the  case  with  Pleischl's  crystals.  The  specific  gravity  of  selenium  varies 
between  4*3  and  4*2.  It  is  brittle,  like  rXvjsb,  not  hard,  easily  scratched 
and  pulverized.  A  mass  of  it  rapidly  cooled  from  a  state  of  fusion  exhibits 
a  red-brown,  metallic-shining  suiface,  and  a  conchoidal  fracture,  the  freshly 
broken  surfaces  having  a  daric  leaden-grey  colour,  and  considerable  lustre : 
after  very  slow  cooling,  it  exhibits  a  granular,  leaden-grey  surfeMse,  and  a 
dull,  fine-grained  fracture.  When  precipitated  by  dilute  sulphurous  acid 
from  a  very  dilute  solution  of  selenious  acid,  the  solutions  beinf  cold  and 
exposed  to  daylight,  it  appears  as  a  golden  yellow  film  :  in  a  less  finely 
divided  state,  as  obtained  from  a  less  dilute  solution,  it  forms  a  scarlet 
powder,  which,  when  the  liquid  is  warmed,  aggregates  to  a  denser  powder, 
first  of  a  dark  red,  and  afterwards  of  a  reddish  black  tint.  Selenium  soli- 
dified  after  fusion  is  reduced  by  trituration  to  a  dark  red  powder,  which, 
in  those  parts  where  it  is  pressed  together  and  polished  by  the  pestle,  ex- 
hibits a  grey  colour  and  metallic  lustre. 

IT  According  to  Count  Schaffgotsch  {J.  pr.  Chem.  43, 308),  the  specific 
gravity  of  selenium  rapidly  oool^  from  fusion  is  4*282;  that  of  granular 
selenium,  4*801 ;  and  that  of  dark  red  precipitated  selenium,  and  of  the 
greyish  black  variety  obtained  by  gently  heating  the  latter,  varies  from 
4*259  to  4*264.  The  specific  gravity  of  the  granular  variety  is  to  that  of 
selenium  rapidly  cooled  from  fusion,  as  112*1 :  100.  IT 


236  SELENIUM. 

Selenium  softens  when  heated;  becomes  semifluid  at  100^,  and  per- 
fectly fluid  at  a  somewhat  higher  temperatare.  As  it  cools,  it  remains 
soft  for  a  long  time,  and  may  be  worked  like  sealing-wax  and  drawn  oat 
into  long,  elastic,  transparent  threads.  Boils  below  a  red  heat,  somewhat 
below  700°.  (Mitscherlich,  Poga,  29,  229).  The  colour  of  its  vaponr  is 
yellow,  darker  than  that  of  chlorine  gas,  but  lighter  than  that  of  sulphar 
vapour.  The  vapour  does  not  smell  like  horse-radish :  in  narrow  vesselsr 
it  condenses  to  metallic-shining  drops ;  in  large  vessels,  to  scarlet  flowers; 
and  in  the  air,  to  a  red  cloud.  Selenium  is  a  bad  conductor  of  heat,  and 
a  non-conductor  of  electricity,  but  it  cannot  be  rendered  electrictil  by 
friction.  (Berzelius.)  According  to  Knox,  fused  selenium  conducts  the 
electric  current  of  a  sixty-pair  battery.  According  to  Bonsdorff,  selenium 
becomes  electrical  when  rubbed  in  very  dry  air. 


Compounds  of  Selenium. 
Selenium   and  Oxygen. 


Selenium  exhibits  less  affinity  for  oxygen  than  sulphur  :  when  gently 
heated  in  the  air,  it  sublimes  without  change,  and  does  not  take  fire  till 
more  strongly  heated,  e.  g,  by  contact  with  flame ;  it  then  bums  in  the 
air  with  a  reddish-blue  flame,  and  in  oxygen  gas  with  a  flame  which  is 
white  below  and  bluish-green  above, — and  is  converted,  partially  at 
least,  into  selenic  oxide  and  selenious  acid.  (Berzelius.) 

A.    Selenic  Oxide.    SeOI 

Formed,  together  with  selenious  acid,  in  the  combustion  of  selenium 
in  air  or  in  oxygen  gas;  in  small  quantities,  also,  when  selenium  is  heated 
in  contact  with  selenious  acid,  both  substances,  however,  subliming  for  the 
most  part,  without  change.  It  is  formed  in  larger  quantity  by  heating 
sulphide  of  selenium  with  a  mixture  of  nitric  and  hydrochloric  acid,  in 
which  the  quantity  of  nitric  acid  present  is  not  sufficient  for  the  complete 
oxidation  of  the  selenium.  From  the  selenious  acid  produced  at  the  com- 
mencement of  the  action,  the  sulphur  which  still  remains  nnoxidized 
again  withdraws  selenium.  Selenic  oxide  gas  is  obtained,  mixed  with 
oxygen,  by  burning  selenium  in  a  vessel  filled  with  oxygen  gas,  and 
removing  the  selenious  acid,  which  is  produced  at  the  same  tune,  by 
agitation  with  water. 

Colourless  gas,  with  an  odour  like  that  of  horse-radish,  and  so  strong 
and  penetrating,  that  -^  ofa  grain  of  selenium  is  sufficient  to  fill  a  room 
in  which  it  is  burned,  with  the  odour.     It  does  not  redden  litmus. 

But  slightly  soluble  in  water,  to  which  it  imparts  its  odour,  but  no 
taste :  by  aqueous  solutions  of  alkalis,  it  is  absorbed  only  in  proportion  to 
the  quantity  of  water  present.  Not  precipitated  from  its  solution  in 
water  by  hydrosulphurio  acid.  (Berzelius.) 

B.    Selenious  Acid.    SeO^. 

Acide  Bilenieux,  SeUnige  Saure :  formerly  called  Selenic  acid. 

Formation.  1.  When  selenium  is  burnt  in  air  or  oxygen  gas,  the 
oxide  being  formed  at  the  same  time. — 2.  When  selenium  is  treated  with 
nitric  acid  or  aqua  regia,  or  with  sulphuric  acid  and  peroxide  of  man- 
ganese. (Berzelius.)     Also  when  oil  of  vitriol  is  boiled  with  selenium. 


SELENIOUS  ACID.  237 

(Gm.)  Cold  nitrio  acid  haa  scarcely  any  action  on  seleniam ;  bat  tbe 
same  acid  when  heated  acts  vigorously  on  it ; — aqua  regia  acts  still  more 
powerfully. 

Preparation.  When  selenium  is  heated  in  a  glass  bulb  till  it  boils^ 
and  oxygen  gas  passed  over  it,  combustion  ensues  and  selenious  acid 
sublimes. — 2.  When  selenium  is  dissolved  in  warm  nitrio  acid  or  aqua 
regia,  and  the  liquid  heated  in  a  retort,  nitric  and  hydrochloric  acids 
distil  over  at  first,  and  subsequently  selenious  acid  subhmes.  (Berzelius.) 

Properties.  Sublimes  in  white,  four-sided  needles,  often  two  inches 
long,  and  having  a  peculiar  lustre, — or  if  the  place  where  it  is  deposited 
is  very  hot,  it  forms  a  dense,  white,  translucent  mass.  Under  the  ordinary 
pressure  of  the  air,  it  does  not  fuse  when  heated,  but  merely  bakes  together. 
Vaporizes  just  below  the  boiling  point  of  oil  of  vitriol,  and  forms  a  vapour 
of  the  colour  of  chlorine  gas.  Its  taste  is  purely  acid  at  first,  but  after- 
wards burning.  In  the  state  of  vapour  it  has  a  pungent,  sour  smell. 
(Berzelius.) 

Calcnlation.  Berzelias. 

Se     40  71-43  71-21 

20    ; 16  28'57  28-79 


8eO«  66  100-00  100-00 

Vol.  Sp.gr.      Vol.  Sp.gr. 

Vapour  of  Selenium? 1  166392  =  )  2-7732 

Oxygen  gas     6  6-5558  =  1  1-1093 

Vapour  of  Selenious  acid....  6  232950  =  1  3*8825 

(SeO'  =  494-58  -f  200  =  694*58.     BerzeUus.) 

Decompositions.  1.  Selenious  acid  in  combination  with  ammonia  gives 
up  its  oxygen,  under  the  influence  of  heat,  to  the  hydrogen  of  the  am- 
monia, so  that  nitrogen  and  selenium  are  set  free. 

3NH»,  3SeO«  =  6H0  +  NH»  +  3Se  +  2N. 

The  decomposition,  however,  is  not  complete :  a  quantity  of  gas,  which 
appears  to  be  hydroselenic  acid,  is  evolved,  and  part  of  the  selenious  acid 
remains  undecomposed,  some  of  it  passing  over  with  the  ammoniacal  liquid, 
while  the  rest  remains  in  the  fixed  residue.  On  this  reaction  depends 
the  separation  of  selenium  from  selenite  of  potassa  by  heating  that  salt 
with  hydrochlorate  of  ammonia,  selenite  of  ammonia  being  first  produced 
by  double  affinity.— 2.  Sulphurous  acid,  or  an  alkaline  sulphite  to  which 
hydrochloric  acid  is  gradually  added,  precipitates  selenium  from  aqueous 
selenious  acid  in  red  or  reddish-black  flakes :  at  low  temperatures  and  in 
the  dark,  the  action  is  slow;  but  in  direct  sunshine,  or  when  aided  by  heat, 
the  precipitate  is  rapidly  formed.  (Berzelius.) 

SeO*  +  2S0*  =  Se  +  2S0«. 

The  precipitation  is  not  completed  in  less  than  half  an  hour's  boiling.  If 
the  mixture  contains  nitric  acid,  the  selenium  is  not  completely  preci- 
pitated till  the  nitric  acid  is  decomposed  by  the  addition  of  a  proper 
quantity  of  sulphurous  acid :  in  such  a  case,  therefore,  it  is  better  to  free 
tne  liquid  from  nitric  acid  by  previous  evaporation  with  hydrochloric 
acid,  and  then  treat  it  with  sulphurous  acid.  (Berzelius.)  Hyposulphite 
of  ammonia,  in  the  cold,  precipitates  only  a  trace  of  selenium  mixed  with 
sulphur ;  a  larger  quantity  is  separated  on  boiling,  and  still  more  on  the 


238  SELENIUM. 

addition  of  bjdrocbloric  acid.  (H.  Rose,  Pogg,  83,  239.)  In  the  cold,  tbe 
decomposition  takes  place  verj  slowly,  if  at  all :  on  boiling,  bowerer^^ 
bisulphide  of  selenium  is  deposited : 

SeO«  +  2SH>«  =  SeS«  +  2S0»: 
the  addition  of  aqua  regia  immediately  decomposes  the  bisulphide   o£ 
selenium.   (Muspratt.)— 3.  Selenious  acid  mixed  with  hydrochloric  acid 
deposits  selenium  upon  iron  and  zinc,  either  in  the  form  of  a  dark  copper- 
coloured  film,  or  in  red-brown  or  blackish-grej  flakes,  according  to  the 
temperature.     The  deposit  formed  on  iron  is  mixed  with  selenide  of  iron. 
Selenious  acid  behaves  in  a  similar  manner  when  mixed  with  other  acids: 
when  sulphuric  acid  is  present,  the  selenium  is  deposited  yery  slowly,  and 
contains  sulphur :  if  the  liquid  also  contains  arsenious  acid,  the  preci- 
pitation IB  extremely  slow.  (Berzelius.)     All  the  metals,  from  zinc  ap  to 
silver  (therefore  neither  ^old,  platinum,  nor  palladium),  precipitate  se- 
lenium from  selenious  acid  mixed  with  sulphuric  acid.     Silver  becomes 
covered  with  a  film  of  selenide  of  silver,  whence  its  surface  assumes  a 
yellow  and  brown  tint :  it  exhibits  this  appearance  even  in  liquids  con- 
taining only  from  TVtWv  ^  tv.W?  ^^  selenium.  (Fischer,  Kcutn,  Arch. 
13,  228;  Pogg,  10,  152.)— -4.  Selenious  acid  heated  with  selenium  remains 
for  the  most  part  unaltered,  only  a  small  quantity  being  converted  into 
selenic  oxide. — 5.  Selenious  acid  doubtless  gives  up  its  oxygen,  under  the 
influence  of  heat,  to  hydrogen,  carbon,  boron,  phosphorus,  sulphur,  organic 
substances,  and  many  metals. — 6.  Hydrosulphuric  acid  and  selenious  acid* 
form,  by  double  decomposition,  selenide  of  sulphur  and  water.  (Berzelius.) 
SeO<  +  2HS  »  SeS'  +  2HO. 

The  complete  decomposition  of  selenious  acid  by  hydrosulphuric  acid  is 
as  difficult  as  that  of  arsenic  acid  by  the  same  reagent.  (H.  Rose,  Pogg. 
42,  538.)  Selenious  acid  is  not  decomposed  in  the  slightest  degree  by 
boiling  with  hydrochloric  acid.  (Berzelius.) 

OomMnatums,  a.  With  Water,  a.  Hydrate  of  Sdmious  acid.~^ 
Crystallizes  from  a  hot  aqueous  solution,  on  slow  cooling,  in  large,  lon- 
gitudinally striated  crystals,  very  much  like  those  of  nitre :  by  rapid 
cooling,  it  is  obtained  m  small  grains.  It  is  also  formed  on  exposing  the 
crystals  of  the  anhydrous  acid  to  the  air :  these  crystals  lose  toeir  lustre 
as  they  attract  moisture  from  the  air,  and  stick  together  without  becoming 
wet  The  hydrate  when  heated  first  eives  up  its  water,  the  anhydrous 
acid  not  subliming  till  the  heat  is  considerably  increased.  (Berzelius.) 

P,  Aqueous  Selenioui  acid.  The  acid  dissolves  very  easily  in  cold 
water;  in  hot  water  it  is  soluble  in  almost  all  proportions.  (Berzelius.) 

b.  With  Salifiable  Bases,  selenious  acid  forms  the  class  of  salts  called 
Selenites,  Its  affinity  for  salifiable  bases  is  considerable ;  but  in  this  re- 
spect it  appears  to  be  always  inferior  to  sulphuric  acid,  and  in  most  cases 
to  nitric  and  hydrochloric  acid  also.  It  withdraws  oxide  of  lead  from 
hydrochloric  acid,  and  the  oxides  of  lead  and  silver  from  nitric  acid. 
Among  the  selenites  are  salts  containing  one,  two,  and  four  atoms  of  acid 
to  one  of  base :  the  number  of  basic  selenites  is  but  small.  The  normal 
alkaline  selenites  have  always  an  alkaline  reaction,  and  a  taste  not 
characteristic  of  the  acid,  but  purely  saline.  The  biselenites  have  an  acid 
reaction.  The  protoxides  of  lead,  copper,  silver,  and  the  di-oxide  of 
mercury,  do  not  combine  with  two  atoms  of  selenious  acid.  If  an 
alkali  be  combined  with  such  a  quantity  of  selenious  acid  as  to  form 
a  solution  neutral  towards  vegetable  colours,  this  solution,  when  con- 


SELENIC  ACID.  239 

centrated  by  evaporation^  yields  crystals  of  alkaline  blselenite,  while 
a  normal  salt  remains  in  solution^  and  gives  an  alkaline  reaction  to  the 
liquid.  Selenites  with  foar  atoms  of  acid  are  found  onlv  among  the 
alkalis. — Many  metallic  selenites,  when  heated,  give  np  all  their  acid ; 
others,  as  the  lead-salt,  only  a  part;  others,  again,  give  up  none. 
The  selenites,  when  ignited  with  charcoal,  evolve  carbonic  oxide  and 
carbonic  acid  gases  without  detonation,  and  are  either  converted  into 
metallic  selenides  by  giving  up  part  of  their  selenium — as  is  the  case  with 
the  selenites  of  the  fixed  alkalis  and  many  heavy  metallic  oxides,^-or 
they  part  with  the  whole  of  their  selenium  and  leave  metaUic  oxide,  as  is 
the  case  with  the  earthy  selenites.  (Berzelius.)  The  selenites  fused  upon 
charcoal  with  microsmic  salt  or  carbonate  of  soda,  in  the  inner  blow-pipe 
flame,  emit  the  odour  of  horse-radish.  The  msuss  obtained  by  fusion  with 
carbonate  of  soda  colours  silver  foil  on  the  addition  of  water,  in  the  same 
manner  as  that  obtained  with  sulphates.  (H.  Rose.)  Selenites  ignited 
with  sal-ammoniac  in  a  glass  tube  or  retort,  yield  a  sublimate  of  selenium. 
Their  solution  in  water  or  hydrochloric  acid  gives  with  sulphurous  acid, 
in  the  cold,  a  red  precipitate  of  selenium,  but  when  heated,  a  grey  preci« 
pitate.  Their  solutions  in  acids  deposit  upon  zinc  a  coatinff  of  selenium, 
copper-coloured  at  first,  but  afterwards  becoming  brown  and  black.  Mixed 
with  aqueous  hydrochloric  acid,  they  give  with  sulphuretted  hydrogen  a 
precipitate  of  sulphide  of  selenium,  which  is  yellow  when  formed  in  the 
cold,  but  yellowish  red  when  separated  at  higher  temperatures.  When 
sulphuretted  hydrogen  gas  is  passed  through  aqueous  solution  of  selenite 
of  ammonia,  pota^a»  or  soda,  the  same  reddish-yellow  precipitate  is 
formed ;  but  it  soon  turns  black-brown,  because  the  monosulphide  of  the 
metal  (or  simple  alkaline  hydrosulphate)  produced,  abstracts  sulphur  from 
it,  and  is  itself  converted  into  pentasulphide  of  the  metal  (or  alkaline 
hydrosulphite).  On  passing  the  hydrosulphuric  acid  gas  through  the 
solution  for  a  longer  time,  sulphur  is  precipitated  almost  free  from  selenium, 
and  the  preceding  compound  is  converted  into  a  double  sulphide  of  hy- 
drogen and  the  metal  (bi-hydrosnlphate  of  the  alkali).  Boracio,  phos- 
phoric, and  sulphuric  acid,  with  the  aid  of  heat,  expel  selenious  acid  from 
its  salts.  Hyorochloric  acid  has  no  action  on  the  selenites.  The  normal 
selenites  of  ammonia,  potassa,  and  soda,  are  soluble  in  water;  the  other 
normal  selenites  are  nearly  or  quite  insoluble ;  the  biselenites  and  tetra- 
selenites  are  easily  solublfe.  All  selenites  are  soluble  in  nitric  acid;  the 
lead  and  silver-salts,  however,  dissolve  with  difficulty.  (Berzelius.) 
Hence  those  selenites  which  are  soluble  in  water,  give  witn  baryta-salts  a 
precipitate  which  is  soluble  in  hydrochloric  or  in  nitric  acid.  (H.  Rose.) 
c.  Selenious  acid  is  easily  soluble  in  alcohol.  (Berzelius.) 


C.    Selbnic  Acid.    SeO*. 

Acide  Bil6nique,  Selensaure, 

Formatum,  1.  When  selenium,  metallic  selenides,  selenious  acid,  or 
any  of  its  salts,  are  ignited  with  nitrate  of  potassa  or  soda.— 2.  When 
chlorine  gas  is  passed  through  solution  of  selenite  of  potassa  mixed  with 
free  potassa.  (Berzelius.)  3.  When  selenium  or  selenious  acid  is  brought 
in  contact  with  water  and  excess  of  chlorine  (H.  Rose),  or  with  hypo- 
chlorous  acid.  (Balard.) 

Not  known  in  the  separate  state. 


240  SELENIUM. 

Calculation.  Mitscherlich. 

Se     40  62-5  61.4 

30    24  37-5  38-6 

SeO»  64  lOO-O  1000 

(SeO«  =  494-58  +  3  .  100  =  794*58.    Berzelins.) 

ComMnatioru,     a.  With  Water.     AqueotuSelenicAcid.     1.  Selenium 
free  from  sulphur  is  dissolved  in  excess  of   nitric  acid — the  solution 
(which  should  not  give  a  precipitate  with  chloride  of  barium^  otherwise 
it  contains  sulphuric  acid)  saturated  with  carbonate  of  soda — the  mixture 
evaporated  to  dr3mess — the  remaining  mixture  of  selenite  and  nitrate  of 
8oda  fused  in  a  porcelain  crucible  at  a  low  red  heat — the  seleniate  of  soda 
separated  from  the  nitrate  in  the  manner  described  on  page  234,  S,  b — 
and  the  seleniate  purified  by  reciystallization.      It  is  then  dissolved  in 
water — the  solution  treated  with  nitrate  of  lead — and  the  precipitated 
seleniate  of  lead,  after  being  well  washed  and  diffused  through  water, 
decomposed  by  hydrosulphuric  acid.     Lastly,  the  solution  is  filtered  and 
concentrated  oy  evaporation.     If  the  acid  thus  obtained  will  not  vola- 
tilize completely,  it  contains  soda-salt,  in  consequence  of  the  seleniate 
of  lead  not  having  been  thoroughly  washed :   in  this  case,  it  must   be 
saturated  with  oxide  of  copper,  the  seleniate  of  copper  purified  by  crys- 
tallization, and  its  aqueous  solution  decomposed  by  sulphuretted  hyorogen. 
If  it  still  contains  sulphuric  acid,  it  will  give  a  precipitate  with  chloride 
of  barium,  after  being  boiled  with  nitric  acid.     Any  nitric  acid  which 
may  be  mixed  with  it  goes  off  during  the  process   of   concentration. 
(Mitscherlich.)     Selenic  acid  may  also  oe  prepared  by  throwing  a  mix- 
ture of  1  part  of  selenium  and  3  parts  of  nitre,  by  small  portions  at  a  time, 
into  a  red-hot  crucible,  in  which  it  explodes,  then  dissolving  the  residue 
in  water,  precipitating  with  nitrate  of  haryta,  &c. ;  or  else,  by  mixing  an 
aqueous  solution  of  selenite  of  potassa  with  a  quantity  of  potassa  equal 
to  that  which  it  already  contains — then  saturating  with  chlorine  gas — 
precipitating  the  resulting  mixture  of  seleniate  of  potassa  and  chloride  of 
potassium  with  a  boiling  solution  of  chloride  of  lead,  washing  the  preci- 
pitate thoroughly,  &o.  (Berzelins.) — 2.  Chlorine  gas  is  passed  in  excess 
through  aqueous  selenious  acid : 

SeO«  +  CI  +  HO  =  SeOs  +  HCI; 

or  chlorine  gas  is  slowly  passed  over  moistened  selenium-powder,  which 
is  frequently  stirred  about  till  the  selenium  is  converted  into  bichloride; 
the  solution  is  then  largely  diluted  with  water,  more  chlorine  passed 
through  it,  and  the  excess  of  chlorine  allowed  to  escape  by  exposure  to 
the  air.  In  this  manner,  a  dilute  solution  of  selenic  and  hy(&ochloric 
acid  is  obtained:  it  cannot,  however,  be  concentrated  by  evaporation 
without  being  reconverted  into  selenious  acid  and  chlorine.  (H.  Rose, 
Po^^.  45,  337.) 

The  concentrated  aqueous  solution  of  selenic  acid  is  a  transparent  and 
colourless  liquid.  When  evaporated  till  the  temperature  reaches  165"^ 
(329°  F.)  its  specific  gravity  is  2*524  :  if  the  concentration  be  continued 
till  the  temperature  rises  to  267""  (512*6°  F.)  the  specific  gravity  is 
increased  to  2*600;  and  after  further  concentration  to  285^*  (545*  F.), 
in  which  case,  part  of  the  acid  becomes  changed  into  selenious  acid,  the 
specific  gravity  becomes  equal  to  2625.  The  acid  evaporated  to  280* 
(536°  F.)  contains  84*21  per  cent,  of  acid  to  15*75  of  water,  or  rather  more 
than  1  atom  of  water  to  1  atom  of  acid.     The  tendency  to  decomposition 


HYDROSELENIC  ACID.  241 

at  hie^h  temperatures^  preyenta  the  formation  of  tLe  pure  hydrate.  (Mit- 
schenich.) 

When  heated  above  285°,  selenic  acid  is  resolved  into  oxygen  and 
selenious  acid.  When  it  is  boiled  T^ith  hydrochloric  acid,  chlorine  gas 
and  selenious  acid  are  produced ;  and  a  mixture  of  selenic  and  hydro- 
chloric acid  dissolves  gold  and  platinum,  as  aqua  regia  does.  Aqueous 
selenic  acid,  with  the  aid  of  heat,  dissolves  copper  and  gold — but  not 
platinum — and  is  reduced  to  the  state  of  selenious  acid;  zinc  and  iron  are 
dissolved  by  it,  with  evolution  of  hydrogen  gas.  It  is  not  decomposed 
either  by  sulphurous  or  by  hydrosulphuric  acid.  The  concentrated  acid, 
when  mixed  with  water,  evolves  as  much  heat  as  oil  of  vitriol  does ;  it 
also  absorbs  moisture  from  the  air.  (Mitscherlich.) 

h.  With  Salifiable  Bases  :  SeleniaUB.  The  affinity  of  selenic  acid  for 
salifiable  bases  is  almost  as  great  as  that  of  sulphuric  acid.  The  seleni- 
ates  are  isomorphons  with  the  sulphates,  chromates,  and  manganates. 
Most  of  them  sustain  a  red  heat  without  decomposition.  They  detonate 
on  glowing  charcoal  (Mitscherlich),  emitting  an  odour  of  selenium,  and 

fenerally  leaving  a  metallic  se7enide.  (Berzelius.)  Heated  before  the 
lowpipe  with  microcosmic  salt  or  carbonate  of  soda,  they  exhibit  the 
same  appearance  as  the  selenites.  (H.  Rose.)  The  seleniates  are  reduced 
to  selenides  by  hydrogen  ffas  at  a  temperature  much  lower  than  that 
which  is  required  for  the  reduction  of  sulphates  to  sulphides.  (Berzelius.) 
When  heated  with  sal-ammoniac,  they  are  reduced,  with  separation  of 
selenium.  Boiled  with  hydrochloric  acid,  they  yield  selenious  acid 
and  chlorine  (whereby  they  acquire  the  power  of  dissolving  gold, 
and  decolorizing  tincture  of  indigo),  whence  they  become  decomposible 
by  sulphurous  or  hydrosulphuric  acid  (which  separate  selenium  or 
selenide  of  sulphur  from  them),  and  no  longer  give  a  precipitate  with 
chloride  of  barium.  (Mitscherlich.)  The  insoluble  seleniates  require 
long  boiling  with  hydrochloric  acid  to  decompose  them  in  this  manner. 
(H.  Rose.)  The  selenic  acid  contained  in  them  is  not  decomposed  by 
sulphurous  or  hydrosulphuric  acid.  All  normal  seleniates  are  soluble  in 
water,  excepting  the  baryta,  strontia,  and  lead  salts,  which  are  nearly  or 
quite  insoluble  in  water  and  in  aqueous  nitric  acid.  (Hydrochloric  acid 
may  exert  a  gradual  solvent  action  by  reducing  the  selenic  to  selenious 
acid.)  Hence  the  soluble  seleniates  give  with  baryta  salts  a  precipitate 
insoluble  in  acids. 

Selekitth  and  Hydrogen. 

Htdroselenic  Acid.     HSe. 

SelenxurettedEydrogen,  Selenide  of  Hydrogen,  ffydroseten,  Selentoas$erstoff, 
Wassergtqf'Selenid,  JSydroselensaure,  Acide  hydrosilHique,  Acide 
Sil&nhydrique,  Silhiide  hydrique; — ^and  in  the  gaseous  state :  Hy^ 
dro9elenic  acid  gas,  Seleniuretted  Hydrogen  gaSy  Hydroselengas,  SeUn* 
wasserstoffgas,  Gas  acide  hydroselenique,  SfC, 

Formation.  In  the  decomposition  of  a  metallic  selenide  by  a  hydrated 
acid.  (Berzelius.)  According  to  Pleischl  (^Kastn,  Arch.  4,  339^,  a  small 
quantity  of  hydroselenic  acid  is  likewise  evolved  in  the  sublimation  of 
selenium  moistened  with  water. 

Preparation.     Dilute  hydrochloric  acid  is  poured  upon  selenide  of 

VOL.    II.  R 


242  SELENIUM. 

potaasium  or  selenide  of  iron^  and  the  evolved  gas  collected  over  mercury. 
(Berzelius.) 

Fropertiei.  Colourless  gas.  Sp.  gr.  {vid.  I.,  279).  Smells  at  first 
like  hydrosulphario  acid ;  but  subseqaentlj  produces  dryness,  and  a  pun- 
gen  t|  astringent,  and  painful  sensation  in  all  parts  of  the  mucous  mem- 
brane of  the  nose  with  which  the  gas  has  come  in  contact :  a  bubble  of 
the  gas  no  larger  than  a  pea  produces  inflammation  of  the  eyes;  destroys 
the  sense  of  smell  for  several  hours ;  and  frequently  brings  on  a  cold  in 
the  head«  or  a  dry  painful  cough,  which  lasts  for  a  fortnight. 

Calculation.  Benelias. 

8e    40  97-56  97*56 

H 1  2-44  2-44 

HSe  41  10000  100-00 

Vol.  Sp.  gr.  Vol.  Sp.  gr. 

Vapour  of  Selenium  ....  1  16-6392  )  27732 

Hydrogen  gas    6  0*4158  1  00693 

Hydroaelenicacidgaa....  6  17*0550  1  2*8425 

(H*Se  =  2  .  6-24  +  494*58  =  507*06.    BeneUua.) 

Deoompositiom,  1.  Hydroselenic  acid  gas,  in  contact  with  moist  sub- 
stances and  with  air,  forms  water  and  selenium,  which,  when  the  bodies 
are  porous,  like  wood  or  paper,  colours  them  red  throughout  their  sub- 
stance. (Berzelius.) — 2.  One  volume  of  hydroselenic  acid  gas,  in  contact 
with  heated  tin,  produces  selenide  of  tin  and  one  volume  of  hydrogen  gas. 
Hydroselenic  acid  gas  collected  over  impure  mercury  is  abo  converted, 
in  the  course  of  a  week,  into  hydrogen  gas — the  mercury  becoming 
covered  with  a  copper^ooloured  deposit.  (Bineau,  Ann.  Chim*  Fhy$,  Q7, 
230;  68,  424.) 

Combinatums.  a.  Aque<m$  Hydroidenic  Acid,  SeleniureUed  Hydro- 
gen Water,  Water  absorbs  hydroselenic  acid  gas  more  abundantly  than 
hydrosulphuric  acid.  To  observe  the  absorption,  water  freed  from  air  by 
boiling  is  passed  up  into  the  gas  standing  over  mercury.  The  solution  is 
a  colourless  liquid  of  faint  odour  and  hepatic  taste ;  it  reddens  litmus  and 
produces  a  permanent  dark-brown  stain  on  the  skin.  When  exposed  to 
the  air,  it  becomes  turbid  and  red,  the  change  progressing  from  above 
downwards  ;  at  length,  complete  decomposition  ensues,  and  the  selenium 
is  precipitated  in  red  flakes.  A  small  quantity  of  nitric  acid  does  not 
decompose  it  in  the  course  of  twelve  hours.  In  contact  with  the  greater 
number  of  heavy  metallic  oxides  dissolved  in  acids,  it  forms  water  and  a 
metallic  selenide,  the  latter  compound  separating  in  the  form  of  a  brown 
or  black  precipitate.  With  the  salts  of  cerium,  manganese  and  zinc, 
aqueous  hydroselenic  acid  gives  flesh-coloured  precipitates  of  hydrated 
metallic  selenide,  or  hydroseleniate  of  metallic  oxide.  (Berzelius.) 

h.  With  Salifiable  Bases.  [Hydroseleniatei.  (Vid.  Metallic  SeU- 
nides.) 

Sblbniuh  and  Phosphorus. 

Sblenide  op  Phosphorus.  The  two  bodies  are  miscible  in  all  propor- 
tions at  temperatures  near  the  melting  point  of  phosphorus.  Phosphorus 
combined  with  a  large  quantity  of  selenium  forms  a  dark-brown,  shining, 
easily  fusible  mass,  of  conohoidal  fracture.   When  a  compound  containing 


SELENIUM  AND  SULPHUR.  243 

excess  of  phosphorns  is  distilled,  the  phosphorus  is  erolyed,  together 
with  a  small  quantity  of  selenium,  in  red,  translucent  drops,  which  when 
cold  exhibit  a  brownish-yellow  colour  and  crystalline  texture.  To  warm 
water,  selenide  of  phosphorus  imparts  a  small  quantity  of  hydroselenio 
acid  ;  in  heated  solution  of  potash  it  dissolyes,  forming  seleniae  of  potajs- 
slum  or  hydroseleniate  of  potassa,  and  phosphate  of  potassa.  (Berzelius*) 

SELSNItTM  AND  SuLPHUB. 

A.  Selbnidb  of  Sulphur.  Sulphur  and  selenium  may  be  fused  toge- 
ther in  all  proportions.— a.  S^Se  is  obtained,  on  passing  hydrosulphurio 
acid  gas  into  aqueous  hydroselenio  acid,  in  the  form  of  a  precipitate  which 
is  first  lemon-yellow  and  afterwards  orange-yellow, — remains  for  a  long 
time  suspended  in  the  liauid — is  deposited  more  readily  on  the  addition 
of  hydrochloric  acid — collects  together,  when  the  liquia  is  heated,  in  the 
form  of  a  fiery-red  mass — and  exhibits  a  red  colour  when  dry.  It  softens 
at  100°  and  melts  at  a  few  degrees  aboye ;  at  a  still  higher  temperature 
it  boils  and  distils  oyer,  forming  when  cold  a  transparent  orange-yellow 
substance  like  orpiment.  When  it  is  burnt  in  the  air  sulphurous  acid  is 
the  chief  product  at  first ;  afterwards  selenio  oxide  is  formed ;  if  the  su^ 
pl^  of  air  is  but  limited,  part  of  the  selenium  sublimes  unbumt.  Nitnc 
acid  decomposes  selenide  of  sulphur  but  slowly;  aqua  regia>  easily.  A 
residue  is  left,  consisting  of  sulphur  spotted  with  red,  which  obstinately 
retains  a  portion  of  the  selenium,  and  can  only  be  freed  from  it  by  fusion 
in  the  concentrated  acid  liquid;  it  then  acquires  a  pure  yellow  colour. 
(Berzelius.)  Chlorine  gas  passed  oyer  diselenide  of  sulphur  conyerts  it 
into  a  mixture  of  bichloride  of  selenium  and  chloride  of  sulphur ;  the 
latter  is  easily  yolatilized  by  heat,  and  pure  chloride  of  selenium  is  left 
behind.  (H.  Kose.)  Diselenide  of  sulphur  fused  with  a  small  quantity 
of  carbonate  of  potassa  forms  a  mass,  which,  when  digested  in  water, 
leayes  a  residue  of  selenium;  with  a  larger  quantity  of  carbonate  of 
potassa,  a  perfectly  soluble  compound  is  obtained.  A  small  quantity  of 
cold  solution  of  potash  abstracts  sulphur  from  the  diselenide,  and  leayes 
selenium  containing  a  smaller  quantity  of  sulphur  ;  a  large  quantity  of 
the  potash  solution  dissolyes  out  the  whole  of  the  sulphur  together  with 
a  portion  of  the. selenium,  and  leayes  pure  selenium.  Aqueous  solution 
of  monosulphide  of  potassium  (simple  hydrosulphate  of  potassa)  abstracts 
sulphur  from  this  compound,  forming  pentasulphide  of  potassium  (hydro- 
sulphite  of  potassa)  and  separating  selenium ;  the  same  effect  is  produced 
by  the  double  sulphide  of  hydrogen  and  potassium  (bihydrosulphate  of 
potassa),  but  only  after  longer  boiling.  If  the  liquid  is  in  excess,  it  also 
dissolyes  a  portion  of  selenium  and  leayes  selenium  free  from  sulphur  ;  if 
its  quantity  is  small,  it  does  not  dissolye  any  selenium.  (Benelius.) 

IT  d.  Triselenide  of  sulphur,  S%e,  is  obtained  by  fusing  together  one 
atom  of  selenium  and  3  atoms  of  sulphur.  In  the  fused  state  it  is  black, 
much  less  yolatile  than  sulphur,  and  may  be  distilled  without  alteration. 
When  cold,  it  is  perfectly  transparent  and  of  a  yellowish  red  colour.  It 
remains  for  some  time  soft  and  elastic  like  pkstic  sulphur,  but  is  not  glu- 
tinous like  the  latter.  After  complete  solidification,  it  becomes  opaque 
and  of  a  brick-red  colour.  It  is  perfectly  soluble  in  excess  of  caustic 
alkali :  if  the  alkali  is  not  in  excess,  a  portion  of  the  selenium  remains 
behind,  and  the  alkali  is  conyerted  into  a  metallic  polysulphide.  (Berze- 
lius.) IT 

0.  A  mixture  of  100  parts  of  selenium  uid  1  part  of  sulphur  is  some- 

r2 


244  SELENIUIM. 

what  more  fcBible,  redder^  and  more  transparent  than  pure  selenium. 
When  heated  above  its  melting  point,  it  becomes  viscid,  black,  and 
opaque,  but  after  cooling  down  a  few  degrees,  it  again  acquires  greater 
mobility,  and  becomes  dark-red  and  translucent.— c.  100  parts  of  sulphur 
acquire  a  dirty  orange-yellow  colour  by  fusion  with  I  part  of  seleniam. 
(Berzelius.) 

B.  Selenium  in  Oil  of  Vitriol.  Selenium  dissolves  rapidly  and  in 
large  quantities  in  fuming  oil  of  vitriol,  at  slightly  elevated  temperatures. 
(Magnus.)  It  does  not  combine  with  anhydrous  sulphuric  acid  (Fischer, 
Fogg,  IG,  121).  When  the  clear,  beautiful  green  solution  in  fuming  oil  of 
vitriol  is  mixed  with  water,  it  immediately  deposits  the  selenium  in  the 
form  of  a  red  powder.  Only  about  -^  of  the  whole  quantity  of  selenium 
remains  in  solution,  probably  oxidated  by  contact  of  air  and  converted 
into  selenious  acid;  it  may  be  precipitated  by  sulphuretted  hydrogen. 
(Magnus,  Pogg*  10,  491;  14,  328.)  According  to  Magnus,  the  selenium 
aissolves  in  the  oil  of  vitriol  without  alteration.  According  to  Fischer  (Po^^. 
12,  153)  it  is  first  oxidated,  inasmuch  as  sulphurous  acid  is  formed  in  the 

S recess  of  solution,  and,  on  the  addition  of  water,  this  acid  and  the  oxi- 
dted  selenium  are  reconverted  into  sulphuric  acid  and  free  selenium.  Oil 
of  vitriol  containing  anhvdrons  acid,  dissolves  selenium  at  ordinary  tem- 
peratures; common  oil  of  vitriol  dissolves  it  after  boiling  for  a  little  while. 
The  former  solution,  when  precipitated  by  water,  gives  a  filtrate  which  is 
scarcely  rendered  turbid  by  sulphuretted  hydrogen :  the  latter  fives  a 
filtrate  rich  in  selenious  acid.  Both  solutions  are  dark-green,  become 
yellow  on  boiling,  then  suddenly  colourless,  and  no  longer  give  precipi- 
tates when  mixed  with  water :  they  give,  however,  an  orange-yellow  pre- 
cipitate with  sulphuretted  hydrogen,  because  the  selenium  which  they 
contain  is  in  the  state  of  selenious  acid.  (Gm.) 

Other  Compounds  of  Selenium. 

A.  With  Bromine.— -B.  With  Chlorine. 

C.  With  Metals.  Metallic  Selenidei  or  Seleniureti.  These  compounds 
are  obtained  in  the  dr^  state:  1.  By  directlv  fusing  the  metal  with 
selenium,  the  combination  being  often  attenaed  with  development  of 
light  and  heat,  not  so  vivid,  however,  as  in  the  combination  of  sulphur 
with  the  same  metals.- — 2,  By  precipitating  most  of  the  heavy  metallic 
oxides  dissolved  in  acids  by  means  of  hydroselenic  acid,  or  of  a 
dissolved  selenide  of  an  alkali -metal  (alkaline  hydroseleniate),  or  by 
heating  a  hydrated  metallic  selenide  (hydroseleniate  of  metallic  oxide}. 
— 3.  By  heating  selenium  with  metallic  oxides  or  their  carbonates, 
whereby  part  of  the  selenium  is  converted  into  selenious  acid.  Thus, 
the  alkalis  fused  with  selenium  produce  an  alkaline  selenite  and  a 
metallic  selenide.  (Berzelius,  Schw,  34,  79.) — 4.  By  igniting  selenites  or 
seleniates  with  hydrogen  or  charcoal. — The  metallic  selenides  are  analo- 
gous to  the  sulphides.  The  selenides  of  the  alkali-metals  are  red,  or,  if 
they  contain  excess  of  selenium,  dark  red-brown,  and  have  the  taste  and 
smell  of  the  sulphides  of  the  alkali-metals.  The  other  metallic  selenides 
are  mostly  dark  coloured,  and  exhibit  the  metallic  lustre :  they  are  gene- 
rally more  fusible  than  tbe  metals  which  they  contain.  When  they  are 
heated  to  redness  in  the  air,  the  selenium  burns  slowly  with  a  reddish 
blue  flame,  and  an  odour  of  horse-iudish.  Selenium  is,  however,  more 
difficult  to  drive  off  by  roasting  tlian  sulphur.     The  selenides  are  less 


c 
s 

x: 


METALLIC  SSLENIDES.  245 

easily  solable  in  nitric  acid  than  the  pure  metals;  selenide  of  mercury^ 
almost  insoluble.  Chlorine,  with  the  aid  of  heat,  converts  them  into  chlo- 
ride of  selenium  and  metallic  chloride. 

Compounds  of  Metallic  Selenides  vnth  Water,  which  may  he  regarded  as 
Salts  of  Hydroselenic  acid,  Hydroseleniates,  These  compounds  are  obtained : 

1.  By  bringing  certain  metallic  selenides  in  contact  with  water.  Only  a 
few  selenides,  as  those  of  potassium  and  sodium,  are  soluble  in  water. — 

2.  By  passing  hydroselenic  acid  gas  through  water  in  which  the  base  is 
dissolved  or  duffused :  e,  g.  the  alkalis  and  magnesia.  On  complete  satu- 
ration with  hydroselenic  acid,  aqueous  Dovble  Selenides  of  Hydrogen  and 
the  Metals,  or  Bi-hydroselenvates,  or  Berzelius's  Selenhydrates  are  formed.>— 

3.  By  precipitating  the  salts  of  baryta,  strontia,  lime,  the  earths,  oxide  of 
zinc,  or  protoxide  of  manganese,  by  aqueous  hydroseleniate  of  potassa. — 

4.  By  boiling  selenium  with  the  aqueous  solution  of  an  alkali.  In  this 
case,  a  dark  brown  solution  is  produced  which,  together  with  an  alkaline 
selenite,  contains  a  metallic  poly-selenide  or  an  alkaline  hydroselenite. 

The  hydroseleniates  of  ammonia,  potassa,  and  soda,  are  probably  colour- 
less when  quite  pnre,  but  generally  have  a  red  tinge,  arising  from  excess 
of  selenium.  In  taste  and  smell  they  resemble  the  alkaline  hydrosul- 
phates  j  in  the  state  of  aqueous  solution  they  impart  to  the  skin  a  perma- 
nent stain  of  yellow,  brown,  or  black,  according  to  the  degree  of  concen- 
tration. When  exposed  to  the  air,  they  are  converted  into  caustic  alkali 
or  alkaline  carbonate,  a  metallic-shining  film,  crystalline  on  the  lower 
surface,  being  at  the  same  time  deposited ;  with  acids  they  evolve  seleni- 
nretted  hydrogen.  The  mono-hydroseleniates  of  baryta,  strontia,  lime, 
and  magnesia  are  flesh-coloured,  and  do  not  dissolve  in  water  unless  excess 
of  hydroselenic  acid  is  present,  in  which  case  they  dissolve  as  double 
selenides  of  the  metal  and  hydrogen,  or  as  bi-hydroseleniates,  and  then 
exhibit  similar  relations.  The  compounds  of  byduroselenic  acid  with  other 
earths,  and  likewise  those  with  protoxide  of  manganese  and  oxide  of  zinc 
obtained  according  to  (4),  are  flesh-coloured  precipitates  insoluble  in  water. 
(Berzelius.)  All  these  precipitates  appear  to  derive  their  flesh-colour  from 
excess  of  selenium;  for,  according  to  Beraelius,  they  deposit  selenium 
when  decomposed  by  acids. 


Chapter  VIII. 

IODINE. 


Memoirs  relating  to  the  Sources  of  Iodine,  alphabetically  arranged: 
Angelini.  Schw,  86,  319;  also  Gilb.  73,  d33.-Aschoff.  £r.  Arch.  20, 
148.— Balard.  Ann.  Ckim.  Phys.  28,  178;  also  Schw.  44,350;  also 
Kasln.  Arch.  5,  126.— Bemhardy.  iV.  Br.  Arch.  26,  199.— Berze- 
lius. Schw.  44,  128;  Fogg.  4,  269. — Lehrb.  1,  255. — Bonjean.  J. 
Chim.  Med.  14, 123. — Boussin^nlt.  Ann.  Chim.  Phys.  30,  91 ;  also 
Schw.  46,  113. — Ann.  Chim.  Phys.  54,  163. — Brandes.  Br.  Arch. 
16,  107.— iV^.  Br.  Arch.  13,  156;  15,  157.— Bnssy.  J.  Pharm.  25, 
718;  also*r.  jpr.  Chem.  19,  495.  — Bnstamente.  Ann.  Chim.  Phys. 
62, 110.— Cantu.    Mem.  de  Turin.  29,  221;  also  Schw.  44,  351; 


346  lODINB. 

aim  Eastn,  Ar^.  5,  127.«-€heyallier.  J.  Pharm.  S,  409.'---Creiis- 
burg.  ITadn,  Arch.  27,  221. — ^Dickie.  Ann.  Fharm.  34,  240. — 
Egidi.  Brugn.  Giom.  18,  240;  also  Schw.  45,  128. — ^Emmet. 
SUL  Amer.  J.  IS,  2eO.—FxiohB.  EepeH.  U,27Q.—¥jfe.  Ed,  Phil.  JT. 
\,  254 ;  also  QHh.  66,  241. — Gaultier  de  Glaabry.  Ann.  Chim.  Pkys. 
13,  298 ;  aUo  N.  Tr.  5,  1, 371.— Giiardin.  Compt,  Bend.  14,  618. — 
L.  Gmelin.  Ann.  Pharm.  31,  321. — G&bel.  BepeH.  11,  44. — 
Orager.  N.  Br.  Areh.  26,  60  and  187.— Happ.  i\r.  Tr.  6,  1, 304. — 
Hausmann.  Ann.  Pharm.  22,  170. — Hayes.  Bend.  Jahri,  21,  2, 
217.— Von  Holger.    Zeittdir.  Phy$.  Maih.  9,  75.— HaU.    N.  Tr.  7, 

2,  137;  12,  1,  297.— Hopfer  de  FOrme.  Ann.  Pharm.  21,  73. — 
John.    Sehw.  45,  128;  KaOn.  Arch.  4,  323.— Jonas.    Ann.  Pharm, 

26,  346.— Kriiger.  Schw.  32,  292;  37,  444;  Br.  Arch.  11,  383. — 
Liebig.  Kastn.  Arch.  5,  454. — Mag.  Pha»m.  16,  124. — Marcband. 
J.  pr.  Chem,  1 9,  151. — Meissner.  Schw.  43,  68. — Menxel  &  Cochler. 
Kastn.  Arch.  12,  252;  13,  336;  Schw.  50,  252.— Morin.    J.  Pharm. 

27,  84.— Meyer.  N.  Tr.  5, 2,  430.— Nentwich  &  Pleischl.  Zeittchr. 
Phy$.  Math.  4,  91  and  97. — ^Pfaff  &  Van  der  Smissen.  Schw,  45, 
378. — Prenss.  Ann.  Pharm.  34,  229. — ^Ragainni.  J.  Chim.  Med. 
11,  360.— Del  Rio.  Schw.  50,  494;  51,  253.— ^nn.  Chim.  Phyz.  62, 
110;  abstr.  Pogg.  39,  526.— Sarpbati.  ReperL  59,  314.— Sgani. 
J.  Chim.  Med,  10,  738.— Steinberg.  J.  pr.  Chem.  25,  387. — Stoltze. 
Berl.  Jahrh.  29, 1,  202. — Straub.   Schweix.  Naturw,  Anzeiger.  Jahrg, 

3,  59 ;  also  GW).  66,  249.^tTatingb.  Bepert.  15, 282. — Torosiewicx. 
i?<jp(5r«.34,8;36,169;  61,395;  63,114;  66, 314.— Turner.  N,  Ed. 
Phil.  J.  1, 159.— Vauquelin.  Ann,  Chim.  Phys.  29, 410 ;  also  iV'.  5>. 
11,  1,  25.— A.  Vogel.  Eagtn.  Arch.  6,  333.— Wackenroder.  I^,Br. 
Arch.  15,  197;  17,  187;  24,  140;  26,  321.— Waltl.  Eepert.  66, 
314.— Yniestm.    Ann.  Chim.  Phys.  62,  111;  also  Pogg.  39,  526. 

Iodine  in  general: 

Courtois,  Clement  &  Desormes.  Ann.  Chim.  88, 304;  also  GUb.  48, 867. 
Sir  H.  Davy.  J.  Phys.  77,  456;  also  GUb.  48,  32.— Further: 
PhU.  Trans.  1814,  I.,  74;  Schw.  11,68;  also  GUb.  48,  19.— 
Further:  PhU.  Trans.  ISU,  II.,  487;  Schw.  11,  234.— Further : 
Ann.  Chim.  92,  89. — ^Further:  Schw.  16,  343;  also  Ann.  Chim. 
96,  289. 

Vauqueliu.  Ann.  Chim.  90,  239;  also  Schw.  13,  394;  14,  44;  also 
GUb.  48,  305. 

Gay-Lussac.  Ann.  Chim.  88,  811;  also  G^6.  48,  24. — Further:  Ann, 
Chim.  SS,  319;  also  GUb.  48,  372. — Further:  Ann.  Chim.  91,5; 
also  Schw.  13,  384;  also  GUb.  49,  1  and  211. 

Colin.     GUb.  48,  280. 

Colin  &  Gaultier  de  Clanbiy.  Ann.  Chim.  90,  87;  also  GUb.  48,  297; 
also  Schw.  13,  453. 

Inglis.    PhU.  Mag.  /.  7,  441 ;  8,  12  &  1 91 ;  also  /.  pr.  Chem.  7,  394. 

Preparation  of  Iodine : 

Aconm,  Fisher,  Garden.  GUb.  48,  5  and  18.  Thomson,  Wollaston.  GUb. 
48,  277.  Soubeiran.  J.  Pharm.  13,  421?  also  Pogg.  12,  604;  also 
N.  Tr.  16,  2,  132.— Whytelaw.  Pogg.  39,  199.— Bussy.  J.  Pharm. 
23,  17;  also  Ann.  Pharm.  22,  62;  also  J.  pr.  Chem.  13,  251— 
Mohr.  Ann.  Pharm.  22,  66.— Graham.  Elements,  New  Ed.  pp.  492, 
493. 


IODINE.  247 

Iodic  Oxide  and  lodout  Add : 
SexnentinL    Btbl  univ.  25,  119;  also  Schw,  41,  158; — Brngn.  Owm. 

19,  387;  SLiBoSchw.  49,  W3;'-Fhil.  Mag,  J.  4,  892;  aleoJ".  Pharm. 

21,  254;  J.  of  Roy.  Inst  2,  75 ;  abstr.  Schw.  65,  453. 
Pleisohl.    Kastn.  Arch,  6,  155;  also  Schuf.  45,  1. 
Wbhler.  Pogg.  8,  95. 
Mitscherlich.    Fogg.  II,  162;  17,  481. 
IngUa.    PhU.  Mag.  J.  7,  4i2. 

Iodic  and  Hyperiodie  Acid: 

Sernllaa.     Ann.  Ohim.  Phys.  43,  113,  208,  211,  216;  45,  59;  also  Pogg. 

18,  97  and  112;  20,515. 
A.  Connell.    N.  Ed.  PhU.  J.  10,  93  and  337,  11,  72;  also  Schw.  62,  493. 

N.  Ed.  Phil  J.  18,  284. 
Rammelsberg.     lodates.     Pogg.  44,  545. 
Magnus  &  AmmermuUer.     Hyperiodic  Acid.     Pogg.  28,  514. 
Beuckiser.    Ann.  Pharm.  17,  254. 
Millon.     Iodic  Acid.    jV.  Ann.  Chim.  Phys.  19,  400. 

Metallic  Iodides: 

P.  BouUaj.    Ann.  Chim.  Phys.  34,  337;  also  Schw.  50,  362;  N.  Tr. 

16,  1,  122;  abstr.  Pogg.  11,  99. 
Berthemot.    J.  Pharm.  14,  610;  also  N.  Tr.  18,  2, 113. 


lod,  lode,  Varee,  lodum,  lodina.    From  rl  Up,  the  Violet. 

History.  Discorered  in  1812  by  M.  Gonrtois,  a  manufacturer  of  salt- 
petre; yeiy  minutely  examined  by  Gay-Lussac  in  1813 — 1814. 

Sources.  As  iodide  of  mercury  (Del  Rio);  as  iodide  of  silver.  (Vau- 
quelin  ;  Del  Rio.)  In  the  white  lend  ore  of  Catorce  in  Mexico.  (Bus- 
tamente.)  In  very  small  quantities,  in  the  zinc  ore  of  Silesia.  (Menzel  & 
Cochler.)  Sublimes  as  hydriodate  of  ammonia  mixed  with  sal-ammoniac 
in  the  burning  coal-mine  of  Gommentry.  (Bussy.)  As  iodide  of  potassium 
or  sodium  in  nitrate  of  soda  from  Chili.  (Hayes ;  Lembert.^  In  the  rock- 
salt  of  Hall  in  the  Tyrol,  probably  in  the  form  of  iooide  of  sodium. 
(Fuchs.) 

In  the  following  salt-springs,  probably  as  iodide  of  sodium,  calcium  or 
magnesium  :  Bex  (Morin) ;  SUlze  in  Mecklenburg  (Kruger) ;  Kolbere  in 
Pomerania  (John);  Baliuffeln  and  Kbnigsbroan  near  Unna  (Brandos); 
Rehme  near  Minden  (Aschoff);  Schonebeck  (Hermann;  Steinberg);  Halle 
in  Saxony  (Meissner);  Diirrenberff  and  Kosen  (Stoltze);  Artern  and 
Salzungen  (Wackenroder);  Schonalkalden  (Bernhskrdy);  Salzhausen  and 
Kreuznach  (Liebig);  Bolechow  and  Drochobycs  in  Oallicia  (Torosiewiez); 
Kenahwa  in  North  America  (Emmet);  Guaoa  in  the  province  of  Antio- 
quia  in  New  Granada.  (Boussingault.) 

In  the  following  other  mineral  waters: — A  well  at  Sarag08sa(Sgarzi); 
the  thermal  springs  of  Albano  (Raggazini);  spring  near  Sales  in  Piedmont 
(Angelini);  several  saline  springs  near  Ascoli  (Egidi);  hepatic  water  of 
Castel  Nuovo  d'  Asti  (Cantu);  thermal  spring  of  Aix  in  Savoy,  called 


248  IODINE. 

" Source  de  sou/re,^^  (Bonjean);  Bonnington  water,  near  Lei th  ([Tamer); 
Bath  water  ^Br.  Arch.  38,  184);  Marienbad  in  Bohemia,  containing  but 
very  little  iodine  (Berzelius);  Carlsbad  (Creuzburg  and  Nenntwich  & 
Pleischl);  Heilbmnn  in  Bavaria,  rich  in  iodine  (A.  Vogel);  spring  at 
Kiinzig,  in  Bavaria  (WaltH;  medicinal  water  {Kropfuxxsser)  of  HaJl  in 
Austria,  used  for  the  cure  ot  goitre,  (Von  Holger);  hepatic  water  of  Trut- 
kawiec,  and  alkaline  water  of  Iwonicz  in  Gallicia  (Torosiewicz). 

The  quantity  of  iodine  contained  in  sea-water  is  so  small,  that  Ten- 
nant,  Sir  H.  Davy,  Gaultier,  Fyfe,  and  Sarphati  were  not  able  to  find  it. 
Balard  however  found  it  in  the  water  of  the  Mediterranean,  and  Pfaff  in 
that  of  the  Baltic,  which  nevertheless  is  very  poor  in  iodine.  But  plants 
and  animals  which  live  in  the  sea  appropriate  the  iodine  in  large  quan- 
tities, in  the  form  of  iodide  of  potassium,  sodium,  calcium,  or  magnesium; 
and  these  salts  may  be  extracted  from  the  plants  by  water,  either  before, 
or  more  completely  after  incineration. 

Marine  and  littoral  plants  in  which  iodine  is  found : — (the  bracketted 
numbers  denote  the  quantity  of  iodine  in  100  parts  of  the  dry  plant,  as 
determined  by  Sarphati): — Fueus  Filum  (00894),  digitatus  ^0-135^, 
saccharintis  {0'23)f  nodosus  (contains  but  little  iodine),  vedculosus  (O'OOl), 
saccatus  (0-124),  Lorctu  (very  little)  siliquosus  (0'142).  The  following 
plants,  according  to  Davy,  Gaultier,  and  Fyfe,  also  contain  iodine :  Ftunis 
cartUagineus,  membranaceus,  rvhens,  and  pdlmaUu.  Spkcerocoecus  {Cera- 
mium)  Helmintochortos,  according  to  Straub,  Happ  and  Gtaultier;  and 
Sphaerococcus  crispus,  according  to  Sarphati.  Viva  Linza,  pavonia,  urn- 
htlicali8  (0  059),  H.  Davy,  Sarphati;  and  Lacttica  (0*055),  Sarphati. 
Zostera  marina  (0*0005),  Balard,  Sarphati.  Lichen  confinu^  Statice 
armeria,  and  Grimmia  maritima,  growing  upon  rocks  on  which  sea-water 
is  sometimes  blown  by  the  wind ;  but  Bamelina  scoptdorum,  growing  in 
the  same  situation,  contains  no  iodine.  (Dickie.)  The  following,  though 
they  grow  near  the  sea,  contain  no  iodine.  SaUola  Kali:  (Fyfe,  Sarphati, 
Dickie.)  FUmtago  maritima  (Fyfe,  Sarphati),  and  Nicotiana  Tabacum 
(Sarphati^.  Filo!  marincB  contain  iodine  (Meyer).  The  ashes  of  various 
species  oi  Ftums,  Ulva,  and  other  sea  plants,  which  constitute  the  Varec 
of  Bretagne  and  Kelp  of  Scotland,  are  rich  in  iodine  (Courtois,  Fyfe);  the 
ashes  of  different  kinds  of  Salsola  and  other  shore>plants,  6.  g.  the 
Spanish  Barilla  and  the  Roman  and  Sicilian  Soda,  contain  little  or  no 
iodine.  ^H.  Davy ;  Fyfe.) 

Marine  animals  containing  iodine :  Common  Sponge  (Gaultier,  Fyfe, 
Straub,  G5bel,  Stratingh);  HorseHSiponge  (Stratingh);  Lapis  spongiarum 
(Happ).  Spongia  ocviata  (Sarphati);  Flustra  foliaeea,  various  species  of 
SerttUaria  and  Ttdmlaria  (poor  in  iodine),  Sarphati ;  various  kinds  of 
Jihizostoma  and  Oyana  (rich  in  iodine),  Sarphati;  Asterias  rubens, 
Crognon  vulgare,  MytUus  edulis  (containing  a  small  quantity  of  iodine, 
but  much  more  bromine),  Sarphati; — Oysters,  various  species  of  Doru 
and  Venus  (Balard).  Pleuronectes  Flems  (containing  a  little  iodine, 
but  much  richer  in  bromine),  Sarphati ; — Cod  liver  oU  (Berger  Lebertkran; 
the  oil  from  the  liver  of  Gadus  Morrhua  and  other  species  of  Gadus) 
contains  iodine  (Hopfer  de  TOrme,  Hausmann,  Brandos,  Wackenroder, 
Grager,  Marchand,  L.  Gemelin);  100  parts  of  the  li^hirbrown  oil  contain, 
according  to  Grager,  0*0846,  and  according  to  Wackenroder,  from  0*162 
to  0-324  parts  of  iodine.  The  oil  from  the  liver  of  Rqja  clavaia  and 
E,  Balis  also  contains  iodine.  (Girardin.)  Salted  Scotch  herrings  con- 
tain a  trace.  (Jonas.)  No  iodine  could  be  detected  in  corals  (Fyfe, 
Stratingh^;  in  the  eggs  of  Buccinum  unda^m  (Saiphati) ;  or  in  isinglass 
(Stratingh.) 


lODINB.  249 

Plaots  and  animals  living  at  a  distance  from  tlie  sea,  but  containing 
iodine :  A  species  of  SaUola  (los  JRomeritos),  which  grows  in  the  floating 
gardens  on  the  fresh-water  lakes  near  tne  city  of  Mexico;  a  kind  of 
Agave,  growing  in  the  plains  and  on  the  mountains  near  Mexico.  (Yniestra.) 
Turf  from  the  neighbourhood  of  Hofwyl.  (Straub.)  The  yellow  juice 
which  exndes  from  Jultu  foetidimmus  when  touched;  this  juice  gives  a 
blue  colour  with  starch^  (HolL) 

Preparation,  Vareo  or  Kelp,  the  ashes  of  various  species  of  Fucus 
and  Ulva,  is  exhausted  with  hot  water;  the  solution  freed  as  much  as 
possible  by  evaporation  and  cooling,  from  the  crystallized  salts  contained 
in  it  (chloride  of  potassium,  chloride  of  sodium,  carbonate  of  soda,  sul- 
phate of  soda,  &c.);  and  the  mother-liquor — which,  besides  iodide  of 
sodium,  still  contains  sulphide  of  sodium,  hvposulphite  of  soda,  and  a  por- 
tion of  the  salts  already  mentioned* — ^is  subjected  to  one  of  the  following 
processes :  1.  It  is  heated  in  a  subliming  apparatus  with  oil  of  vitriol. 
(Sch,  91): 

Nal  +  2S0»  =  NaO,  S0«  +  S0«  +  I. 

This  method  is  not  very  advantageous ;  because  the  sulphurous  acid 
evolved  acts  upon  the  iodine  and  the  water  which  is  present,  in  such  a 
manner  as  to  produce  hydriodic  and  sulphuric  acid.  (Soubeiran.) 

2.  The  mother-liquor  is  heated  in  a  subliming  apparatus  with  per- 
oxide of  manganese  and  oil  of  vitriol.  (WoUaston,  Sch,  67.) 

Nal  +  2SO»  +  MnO»  =  NaO,SO»  +  MnO,SO»  +  I. 

A.  Whjrtelaw  adds  one  measure  of  oil  of  vitriol,  carefully  and  in  small 
portions  at  a  time,  to  eight  measures  of  the  mother- liquor,  contained  in  a 
leaden  boiler — ^whereupon,  carbonic  acid  and  sulphuretted  hydrogen  (from 
the  sulphide  of  sodium)  are  first  evolved ;  and,  after  exposure  to  the  air 
for  a  day  or  two,  sulphurous  acid  (from  the  hyposulphite  of  soda)  escapes, 
and  sulphur  is  precipitated.  He  then  pours  on  the  liquid  from  the  crys- 
tallized sulphate  of  soda  into  a  leaden  cylinder  placed  horizontally  in  a 
sand-bath,  and  fitted  with  a  helm,  the  beak  of  which  passes  into  the  first 
of  three  tubulated  receivers  luted  one  into  the  other;  heats  the  mixture 
to  65°  (149^  F.);  and,  after  adding  the  peroxide  of  manganese  and  putting 
on  the  helm,  gradually  raises  the  temperature  to  100°,  but  not  higher, 
because  at  US'"  (244°  F.)  chloride  of  iodine  begins  to  distil  over.  Some- 
times also,  cyanide  of  iodine  collects  in  the  last  receiver,  in  white,  needle- 
shajped  crystals.  The  lion  id  which  remains  in  the  retort  still  contains 
iodine,  and  on  cooling,  aeposits  crystals  of  iodide  of  lead  and  double 
iodide  of  lead  and  sodium. 

d.  The  mother-liquor  is  evaporated  to  dryness,  the  residue  heated 
with  peroxide  of  manganese,  and  the  iodine  precipitated  from  the  filtered 
solution  bv  chlorine.  BarrueVs  method:  The  residue  obtained  by  eva- 
porating the  mother-liquor  to  dryness  is  mixed  with  -^  of  its  weight  of 
peroxide  of  manganese,  and  the  mixture  heated  in  an  iron  vessel  to  com- 
mencing^ redness  (stirring  all  the  while),  but  not  high  enough  to  cause 
the  evolution  of  vapours  of  iodine :  the  heat  is  continued  till  a  sample  of 
the  mixture  treated  with  sulphuric  acid  no  longer  evolves  sulphuretted 
hvdrogen  or  deposits  sulphur;  that  is  to  say,  till  the  whole  of  the  sul- 
phide of  6odium  and  hyposulphite  of  soda  are  converted  into  sulphate. 

*  A  mother-liquor  from  Varec  examined  by  Sonbeiran  contained  no  carbonate  or 
sulphate:  the  principal  salts  contained  in  it — ^in  addition  to  the  iodides— were  nitrate  of 
lime  and  nitrate  of  magnesia. 


250  lODIKB. 

The  mass  is  then  dissolred  in  such  a  qnantity  of  water  that  the  solution 
may  have  a  density  corresponding  to  36°  of  Baume's  areometer;  chlorine 
gas  is  passed  through  the  filtered  liquid,  which  is  constantly  stirred,  till 
a  sample  treated  with  more  chlorine  no  longer  gives  a  precipitate  of  iodine 
(excess  of  chlorine  would  convert  the  iodine  into  chloride  and  re-dissolve 
it),  and  the  pulverulent  precipitate  of  iodine  is  collected  on  a  filter,  and 
purified  hy  sublimation.  (Bussy.)  Mohr  is  of  opinion  that  a  loss  of  iodine 
may  occur  in  this  process  during  the  heating  of  the  evaporated  residue 
with  manganese. 

4.  The  mother-liquor  is  precipitated  by  a  copper-salt  and  metallic 
iron,  and  the  diniodide  of  copper  heated  with  peroxide  of  manganese. 
Soubeiran^t  method:  The  mother^liquor  is  diluted  with  water,  and  mixed 
with  a  solution  of  sulphate  of  copper,  as  long  as  any  precipitate  is  pro* 
duced: 

2NaI  +  2(CuO,SO»)  =  2(NaO,SO«)  +  C««I  -I-  I; 

the  liquid  containing  the  free  iodine  separated  by  decantation  and 
washing  from  the  precipitated  diniodide  of  copper,  and  mixed  with 
sulphate  of  copper  and  iron  filings  till  it  no  longer  smells  of  iodine : 

1+2  (CuO,  S0»)  +  2Pe  =  Cu«  I  +  2{FeO,  SO»)j 

and  the  diniodide  of  copper  thus  produced,  quickly  separated  by  elutria- 
tion  from  the  excess  of  iron  filings  and  from  the  liquid,  before  the  ferrous 
sulphate  has  time  to  oxidate  in  the  air.  The  two  portions  of  diniodide 
of  copper  obtained  as  above,  are  next  dried  at  a  gentle  heat  (a  stronger 
heat  would  decompose  the  diniodide  of  copper — since  it  is  mixed 
with  disulphate  of  ferric  oxide— and  evolve  iodine);  the  whole  mixed 
with  twice  or  three  times  its  weight  of  peroxide  of  manganese,  and  a 
sufficient  qnantity  of  oil  of  vitriol  to  form  it  into  a  paste;  and  the  mixture 
strongly  heated  in  a  subliming  apparatus : 

Ctt«I  +  2MnO«  +  4S0»  =  2CCuO,SO>)  +  2(MnO,SO»)  +  I. 

Or  the  oil  of  vitriol  is  dispensed  with,  and  a  stronger  heat  applied : 

Cu«I  +  3MnO«  =  2CuO  +  Mn'O*  +  I. 

In  both  cases,  the  iodine  which  passes  over  is  accompanied  by  water 
derived  from  the  hydrated  diniodide  of  copper,  from  the  sulphate  of  lime 
precipitated  with  it,  and  from  the  oil  of  vitriol,  when  it  is  used  in  the 
process.  In  this  water,  a  portion  of  the  iodine  is  dissolved :  it  may  be 
again  precipitated  by  sulphate  of  copper.  By  this  process,  100  parts  of 
the  mother-liquor  yield  1  part  of  iodine. 

Puri/icatum.  The  iodine  obtained  by  the  preceding  processes  is 
purified  hj  washing  with  a  small  quantity  of  water,  pressing  between 
paper,  drying,  and  subliming  a  second  time.  The  iodine  of  commerce 
may  be  completely  purified  by  solution  in  alcohol,  filtering,  and  precipi- 
tating with  water.  (Serullas.) 

Properties.  The  crystalline  system  to  which  iodine  belongs  is  the 
right  prismatic.  Primary  form  :  an  acute  rhombic  octohedron  {Fig.  41, 
42,  43,  46;  also  43,  with  m-faces).  Ratio  of  the  3  axes  =  4:3:2. 
(Wollaston,  Marchand,  Fogg,  31,  540;  Lampadius  &  Breithaupt,  J,  pr, 
Chem,  13,  237); — compare  Plisson  (Ann,  Ckem.  Fhys.  39,  274),  Soubeiran 
{J.  Pharm.  13,  423).  The  finest  crystals  are  obtained  from  solutions; 
e.  g,  from  aqueous  hydriodic  acid  exposed  to  the  air,  or  from  a  solution  of 


IODINE  AND  OXTGEN.  251 

iodine  in  ether.  Iodine  jrields  by  snblimationi  lamina  or  broad  oblique 
tables  formed  by  extension  of  the  p-sorfaoe  (according  to  Plisson  and 
Soubeiran,  acute  rhombohedrons  and  double  sixHsided  pyramids).  Specific 
gravity  =:  4 '948  at  17°.  (Gay-Lussao.)  Very  soft  and  friable  j  may  be 
reduced  to  powder.  Blackish-grey,  with  metallic  lustre,  resembling 
black-lead  or  micaceous  iron  ore;  transmits  light  only  when  in  thin 
pieces;  the  transmitted  light  is  red.  Fuses  at  107°  (224*6°  F.),  and  on 
cooling  solidifies  again  in  a  lamellated  mass.  Boils  (under  oil  of  yitriol) 
between  175°  and  180''  (347° — 356°  F.),  according  to  Gay-Lussac,  and  is 
converted  into  a  violet  vapour  which  deposits  crystallized  iodine  on  colder 
bodies.  The  saturated  vapour  is  so  dark  coloured  that  a  stratum  4  inches 
thick  is  impervious  to  daylight  or  candlelight :  it  appears  blue  on  the 
edges,  and  by  reflected  light  perfectly  black.  (Dumas.)  Specific  gravity 
of  the  vapour  (I.,  279).  Solid  iodine  is  a  non-conductor  of  electricity. 
(Gay-Lussac;  Solly,  Phil.  Mag.  J.  8,  130;  also  Fogg,  37,  420;  Inglis.) 
Fused  iodine  conducts  the  current  of  a  battery  containing  from  60  to  90 
pairs.  (Inglis,  Knox,  Fhil.  Mag.  J.  9,  450;  16,  188.)  The  odour  of 
iodine  resembles  that  of  chlorine,  chloride  of  sulphur,  or  oxide  of  osmium ; 
its  taste  is  sharp  and  astringent;  it  acts  as  a  powerful  poison.  It  exerts 
but  a  feeble  action  on  vegetable  colours.  PulveriEed  iodine  and  the 
saturated  aqueous  solution  decolorize  tincture  of  litmus  and  infusion  of 
red  cabbage,  in  the  course  of  a  few  days.  (A.  Connell,  N.  Ed.  Phil.  J.  12, 
337;  also  Ann.  Pharm.  3,  314.)  Iodine  communicates  a  transient  brown 
colour  to  the  skin  and  to  paper,  due  to  the  formation  of  hydriodous  acid. 
It  produces  a  bright  blue  colour  with  starch  and  meconine.  With  bisul- 
phide of  carbon  and  rock-oil  it  forms  bright,  violet-coloured  solutions. 

Atomic  weiffht  of  iodine:   124  Prout;  Thomson;  125  Gay-Lussao; 
126*56  (the  double  atom)  Benelius. 


Compounds  of  Iodine. 

lODIMB  AND  WaTEB. 


One  part  of  iodine  dissolves  in  7000  parts  of  water  (Gay-Lussac); 
in  500  parts  at  20°  (Jacquelain,  Ann.  Chim.  Phys.  73,  201),  forming  a 
brown  solution,  which  has  the  smell  of  iodine.  The  solution  loses  its 
colour  by  exposure  to  the  direct  rays  of  the  sun  (Ampere);  also  in  per- 
fectly closed  bottles,  provided  they  contain  ur,  but  not  if  they  are  com- 
pletely filled  with  the  liquid.  (Inglis.)  The  decolorized  solution,  when 
brought  in  contact  with  iodine,  dissolves  it,  and  acquires  a  permanent 
orange-yellow  tint.  (Guibourt,  J.  Chim.  Med.  5,  103.)  From  this  it 
would  appear  that  the  decolorized  liquid  contains  hydriodic  acid,  which, 
by  taking  up  an  additional  quantity  of  iodine,  is  converted  into  hydrio- 
dous acid.  (Gm.) 

Iodine  and  Oxygen. 

A.    loDio  Oxide  1 

Oxide  of  Iodine. 

1.  Oxygen  gas  is  passed  through  a  bent  copper  tube  kept  at  a  low 
red  heat,  into  the  tubulure  of  an  empty  retort,  heated  by  a  spirit-lamp; 
and  a  spoon  filled  with  iodine  is  introduced  through  the  neck  of  the 
retort,  in  such  a  manner,  that  the  stream  of  heated  oxygen  may  come 


254  lODINS. 

I  +  sa  +  HO  =  6HC1  +  IO»j 
and  if  an  alkali  be  present,  a  metallio  chloride  and  an  alkaline  iodate  are 
piodaoed  (Gaj-Lussac) ; 

6K0  +  I  +  6C1  =  5Ka  +  KO,  I0». 
4.  Iodine  and  aqneous  solution  of  potassa  form  5  atoms  of  iodide  of  potas- 
sium and  1  atom  of  iodate  of  potassa. 

6KO  +  61  «  5KI  +  KO,IO<; 
or,  what  comes  to  the  same  thing,  5  atoms  of  h  jdriodate  of  potassa  and  1 
atom  of  iodate  of  potiussa  {Sdt,  83  and  34;  for  C\  read  1} : 
6KO  +  61  +  5HO  =  5(K0,HI)  +  KO,IO». 
Similar  products  are  obtained  with  the  other  fixed  alkalis,  and  partially 
also  with  magnesia.  (Gay-Lussac.)     In  like  manner^    mercuric   oxide, 
with  iodine  and  water,  forms  proticKlide  of  mercury  and  iodate  of  mercu- 
ric oxide  (Colin);  and  oxide  of  silver  with  iodine  dissolved  in  alcohol, 
forms  iodide  and  iodate  of  silver.  (Serullas.) — 5.  Oxide  of  sold  in  contact 
with  iodine  and  water,  forms  iodic  acid  and  metallic  gold  (Colin): 
dl  +  5AaO'  »  3I0»  +  5Au. 

Preparation.  Chloric  oxide  gas  is  passed  over  iodine,  a  gentle 
heat  being  applied  to  volatilize  the  chloride  of  iodine  formed  at  the  same 
time.  (H.  Davy.)  Davy  passes  euchlorine  gas  (a  mixture  of  chlorlo 
oxide  and  chlorine)  obtained  by  cautiously  heating  a  mixture  of  1 0  grains 
of  chlorate  of  potassa  and  40  grains  of  hydrochloric  acid,  sp.  gr.  1*105 — 
first  over  chloride  of  calcium,  for  the  purpose  of  drying  it,  and  then  over 
4  grains  of  iodine.  Instead  of  hydrochloric  acid,  Dbl^reiner  {Schw,  16, 
356)  recommends  60  grains  of  oil  of  vitriol,  which  disengages  pure  chloric 
oxiae.  IT  Millon  digests  4  parts  of  iodine  with  7 '5  of  chlorate  of  potassa 
in  40  parts  of  water  acidulated  with  10  of  nitric  acid,  heating  the  liquid 
sufficiently  to  cause  rapid  evolution  of  chlorine.  In  a  short  time  the 
iodine  is  completely  oxidized.  The  iodic  acid  thus  formed  is  precipitated 
by  baryta,  and  separated  a^ain  hj  means  of  sulphuric  acid.  Larger  crystals 
are  obtained  when  the  solution  is  contaminated  with  salphuric  acid  than 
when  it  is  pure.  (Millon,  i^.  Ann,  Chim.  FhyB,  9,  400.)  IT 

2.  Iodine  is  oxidated  by  continued  boiling  with  concentrated  nitric 
acid.  (Connell.)  The  acid  must  be  as  strong  as  possible :  the  admixture 
of  hyponitrio  acid  recommended  by  SeruUas  confers  no  advantage.  To 
prevent,  as  far  as  possible,  the  volatilization  of  the  iodine  in  Uie  acid 
vapours,  a  flask  should  be  used  having  a  long  neck,  and  a  capacity  more 
than  50  times  that  of  the  liquid;  the  lamp  must  be  applied  to  the  bottom 
only  of  the  flask ;  the  sublimed  iodine  frequently  washed  down  again,  and 
the  heat  continued  till  all  the  iodine  is  dissolved  :  as  the  liquid  cools,  the 
iodic  acid  separates  in  a  granular  mass.  The  liquid  is  then  evaporated 
to  dryness,  twice  redissolved  in  water,  and  again  evaporated.  With  the 
removal  of  the  adhering  nitric  acid,  the  iodic  acid  loses  its  crystalline 
aspect,  and  becomes  a  whitish  mass,  frequently  tinged  with  red,  from  sepa- 
ration of  iodine.  (ConneU.)— Boutin  {J,  Fharm,  19,  222)  digests  1  part 
of  iodine  freshly  precipitated  by  water  from  an  alcoholic  solution  (because 
in  this  state  it  is  purer  and  more  finely  divided  than  ordinary  iodine)  in 
a  mixture  of  8  parts  of  strong  nitric  and  2  parts  of  hyponitrio  acid.  The 
iodine  is  first  heated  with  two^thirds  of  the  mixture,  in  a  flask  which  haa 
a  long  neck  and  also  a  long  tube  attached  to  the  neck,  the  liquid  being 
frequently  agitated;  afterwards,  the  remaining  portion  of  the  mixture  is 


IODIC  ACID.  255 

added;  and  when  the  oxidation  is  complete,  the  liquid  is  evaporated  to 
one-third  of  its  bulk :  the  mother-liqaor,  when  cold,  is  poured  off  from 
the  oiYstallized  iodic  acid.  The  latter  is  then  dissolved  in  a  small  quan« 
tity  01  water;  the  filtrate  mixed  with  twice  its  volume  of  nitric  acid,  by 
which  the  iodic  acid  is  precipitated;  the  pale  rose-coloured  liquid  poured 
off;  the  precipitated  acid  dissolved  in  3  times  its  weight  of  water;  3  mea- 
sures of  the  solution  mixed  with  2  measures  of  nitric  acid ;  and  the  mixture 
evaporated  to  dryness.  Duflos  {Sckw.  62,  496)  recommends  nitric  acid  of 
specific  gravity  1  55,  and  as  free  as  possible  from  hj^ponitric  acid.  Acid 
of  this  strengui  begins  to  act  even  in  the  cold.  Acid  of  specific  gravity 
1*35  produces  no  iodic  acid  even  on  boiling.  Hyponitric  acid  is  hurtful : 
it  decomposes  the  iodic  acid  again,  and  precipitates  iodine.  Bourson 
{Cotnpt  liend.  13,  1111 ;  also  J.  pr.  Cfhem.  25,  298)  likewise  recommends 
the  strongest  nitric  acid,  containing  only  1  atom  of  water ;  4  parts  of  it 
convert  1  part  of  iodine,  at  a  gentle  heat,  almost  wholly  into  iodic  acid, 
very  little  iodine  going  off  in  vapour.  The  solution  with  the  crystal* 
line  grains  alreac^  produced  being  evaporated  to  dryness,  the  residue 
exposed  to  the  air  till  it  deliquesces  to  a  syrup,  and  this  s^mw  liquid 
placed  for  a  few  days  in  a  hot-air  chamber,  the  acid  is  obtamed  m  b^u- 
tiful  white  crystals. 

3.  When  terchloride  of  iodine  moistened  with  water  is  treated  with 
alcohol  or  ether,  decomposition  ensues,  and  iodic  acid  is  left  undissolved. 
(Serullas.)    Probably  in  this  manner : 

2IC1*  +  6HO  «  I0»  +  5Ha  +  ICl. 
Hence  it  would  appear  that  the  alcohol  takes  up  hydrochloric  acid  and 
monoohloride  of  iodine.  Iodine  purified  by  solution  in  alcohol,  filtering, 
precipitation  with  water,  washing,  and  drying,  is  completely  saturate 
with  chlorine  gas :  the  terchloride  of  iodine  thus  obtained  is  brought  to 
the  state  of  a  soft  powder  by  shaking  it  up  in  a  bottle  with  pieces  of  bro- 
ken glass  and  a  small  quantity  of  water,  and  transferred  from  the  bottle 
into  a  basin  by  means  of  a  funnel,  whereby  the  pieces  of  elass  (which 
should  be  rinsed  with  a  saturated  solution  of  chloride  of  iodine)  are 
retained.  After  pouring  off  the  watery  liquid — ^which  may  contain  mono- 
chloride  of  iodine,  and  thereby  act  iniuriously — alcohol  of  40®  B.,  or  ether, 
is  added  in  successive  portions  (stirring  continually)  to  the  pulve- 
rised terchloride  of  iodine,  then  decanted  and  renewed,  as  long  bb  it 
acquires  a  yellow  colour.  After  this,  there  remains  a  white  crystalline 
powder  of  pure  iodic  acid,  which  may  be  obtained  in  regular  crystals  by 
solution  in  water,  filtering,  and  evaporation  in  the  hot-air  chamber,  after 
the  addition  of  sulphuric  acid.  (Serullas.)  The  iodic  acid  thus  obtained 
amounts  to  only  •}-  of  the  quantity  of  iodine  employed.  (Liebig,  Fogg, 
24,363.) 

4.  Iodine  diffused  in  water  is  converted  by  excess  of  chlorine  into 
iodic  acid,  and  the  hydrochloric  acid  produced  at  the  same  time  removed 
by  a  suitable  quantity  of  oxide  of  silver.  (Serullajs ;  Thompson.) — 126 
grains  (]  At.)  of  iodine  are  diffused  through  24  oz.  of  water,  and  washed 
chlorine  gas  passed  through  the  liquid  till  it  becomes  colourless.  The 
solution  is  then  freed  from  excess  of  chlorine  by  enosure  to  the  air  for  an 
hour,  and  subsequent  heating  to  100° ;  after  which  it  is  boiled  for  ten 
minutes  with  freshly  precipitated  oxide  of  silver,  and  lastly  filtered  and 
evaporated.  (^Lew.  Thomj^son.)  For  the  removal  of  the  hydrochloric  acid 
produced  in  this  process,  it  appears  to  be  necessary  to  use  not  merely  2|, 
bat  5  atoms  of  oxide  of  silver. 

5.  A  salt  of  iodio  acid  is  decomposed  by  a  stronger  add.— ^.  A  sola- 


256  IODINE. 

tion  of  iodate  of  soda  (iodate  of  potassa  will  not  do,  because  it  gives  up 
only  part  of  its  base,  and  is  converted  into  a  ter* iodate)  is  mixed  with 
excess  of  hydrofluosilicic  acid;  the  liquid  evaporated  to  a  certain  point  ; 
the  acid  filtered  from  precipitated  fluoride  of  silicium  and  sodium ;  evapo- 
rated^ with  gentle  ebullition  and  frequent  addition  of  water,  till  it  acquires 
a  syrupy  consistence,  and  no  longer  smells  of  fluosilicic  acid ;  then  left  to 
cool,  and  filtered  to  separate  it  from  an  additional  quantity  of  precipitated 
fluoride  of  silicium  and  sodium ;  and  finally  dried  at  a  gentle  heat,  whereby 
it  is  rendered  perfectly  solid.  Iodic  acid  thus  prepared  yields,  when 
heated,  only  1  per  cent,  of  fixed  residue.  (Serulbs.) — b.  An  aqueous  solu- 
tion of  iodate  of  soda  is  heated  for  a  quarter  of  an  hour  witn  excess  of 
sulphuric  acid,  to  the  temperature  of  conunencing  ebullition ;  the  filtered 
liquid  placed  in  a  hot-air  chamber  at  20°— 25*  (68''— 77"^  F.)  ;  the  mother- 
liquor,  which  contains  sulphate  of  soda,  sulphuric  acid,  and  a  small  quan- 
tity of  iodic  acid,  poured  off  horn  the  crystallized  iodic  acid ;  and  the 
latter  washed  with  a  very  small  quantity  of  water.  This  process  yields 
a  pure  acid,  which  volatilizes  without  residue.  If,  howeyer,  it  should  still 
contain  a  small  quantity  of  iodate  of  soda,  the  process  of  heating  with 
water  and  sulphuric  acid,  and  subsequent  crystallization,  must  be  repeated 
till  a  pure  acid  is  obtained.  (Serullas.) — c.  Iodate  of  baryta  is  decomposed 
by  dilute  sulphuric  acid.  (6a^-Lussac.^  Liebi^  {Po99*  ^^»  ^^^)  saturates 
water,  in  which  iodine  is  diffused,  with  chlorine ;  neutralizes  the  liquid 
with  carbonate  of  soda ;  passes  chlorine  gas  through  it  till  the  iodine  pre- 
cipitated by  neutralizing  the  liquid  has  been  redissolved;  neutralizes 
again  with  carbonate  of  soda ;  precipitates  the  solution  thus  obtained, 
which  contains  chloride  of  sodium  and  iodate  of  soda,  with  chloride  of 
barium ;  washes  and  dries  the  precipitated  iodate  of  baryta,  boils  9  parts 
of  it  with  24  parts  of  water  and  2  parts  of  oil  of  yitriol  for  half  an  hour ; 
and  evaporates  the  filtrate  to  the  consistence  of  syrup  :  this  liquid,  after 
several  days*  exposure  to  the  air,  yields  beautiful  cnrstals  of  iodic  acid. 
A  similar  process  is  adopted  by  Grosourdy  Uf,  Ghim,  Med,  9,  428). 
Dufios  {Schw,  62,  390)  finds  the  use  of  iodate  of  oaryta  more  advantageous 
than  that  of  iodate  of  soda   (5,  a  and  5,  h). 

To  obtain  the  acid  in  the  crystallized  state,  the  syrupy  solution  is 
either  left  to  itself  in  a  dry  place  at  ordinary  temperatures,  and  the  liquid 
poured  off  before  the  whole  is  solidified,  or  it  is  mixed  with  hydrofiuoric, 
nitric,  or  sulphuric  acid,  and  evaporated  in  the  hot-air  chamber  at  a  mode- 
rate heat.  These  acids  appear  to  favour  crystallization  by  abstracting 
water  from  the  iodic  acid;  moreover,  their  adhesion  to  the  crystallized 
acid  is  merely  mechanical,  so  that  the  crystals  may  be  entirely  freed  from 
them  either  by  pressure  between  bibulous  paper,  or,  if  the  acids  are  vola- 
tile, by  exposure  to  warm  air.  (Serullas.)  Rammelsberg  also  {Pogg,  46, 
159)  found  that  iodic  acid  crystallized  from  a  liquid  containing  sul- 
phuric acid;  was  free  from  water  and  almost  wholly  free  from  sulphuric 
acid. 

Properties,  Iodic  acid  crystallizes  in  six-sided  tables  which  appear 
to  be  segments  of  an  octohedron  TSeruUas).  Sinks  rapidly  in  oil  of  vitriol. 
(H.  Davy.)  It  is  white  (sometimes,  if  it  has  been  too  strongly  heated, 
having  a  pale-red  colour,  from  the  presence  of  free  iodine)  and  translucent. 
(H.  Davy.)  Has  a  very  slight  odour,  peculiar  to  itself,  but  resembling  that 
of  iodine  (Serullas);  tastes  very  sour  and  disagreeable.  (H.  Davy.) 
When  dissolved  in  water,  it  reddens  litmus  paper  and  afterwards  bleaches 
it  (H.  Davy);  reddens  it  permanently  without  bleaching  it.  (Connell.) 


IODIC  ACID.  257 

CalcuUdon.  Vol. 

I  126  75'9  Vapour  of  iodine  2 

50 40  24-1  Oxygen  gas  5 

lO* 166  1000 

(I«0*  =  2 .  789-75  +  5  .  100  ==  2079-50.    BerzeUus.) 

Decompositions.  1.  When  beated  to  the  boiling  point  of  olive  oil,  iodic 
acid  fuses,  and  at  the  moment  of  fosion  is  resolved,  without^residue,  into 
oxygen  gaa  and  vapour  of  iodine.  (H.  Davy.) — 2.  For  the  decomposition 
by  electricity,  vid,  I.,  434,  452. — 3.  When  heated  with  charcoal,  sulphur, 
resins,  sugar,  or  finely  divided  combustible  metals,  it  gives  up  its  oxygen 
to  these  bodies  without  detonation.  (H.  Davy.)— 4.  The  aqueous  acid  is 
decomposed  by  phosphorus,  on  the  application  of  heat,  the  products  being 
iodine,  phosphoric  oxide,  and  phosphoric  acid  (Benckiser);  also  by  phospho- 
rous acid,  on  the  application  of  heat,  forming  iodine  and  phosphoric  acid 
(H.  Davy).  With  a  small  quantity  of  sulphurous  acid,  it  yields  iodine  and 
sulphuric  acid  j  with  a  larger  quantity,  hydriodic  acid  and  sulphurous 
acid;  with  hydrosulphuric  aci{  the  products  are  sulphur,  water,  and 
iodine,  which  by  a  larger  quantity  of  hydrosulphuric  acid  is  converted 
into  hydriodic  acid ;  with  hydriodic  acid,  the  products  are  iodine  and 
water  {Sch,  70;  Gay-Lussac);  with  hydrochloric  acid,  provided  the 
quantity  of  water  present  is  but  small,  terchloride  of  iodine,  water,  and 
cnlorine  are  produced;  with  hjmonitric  acid — only,  however,  when  water  is 
present — ^iodine  and  nitric  acid  (Gaultier  de  Claubry,  Ann,  Chim.  Phys. 
46,  221);  a  case  of  reciprocal  affinity. — Several  metals  abstract  oxygen 
from  iodic  acid.  (H.  Davy.)  The  oxidation  of  gold  and  platinum  by 
iodic  acid,  which.  Sir  H.  Davy  asserted  to  take  place,  is  deniea  by  ConneU 
and  Serullas. — Several  organic  compounds  likewise  separate  iodine  from 
iodic  acid,  so  that  the  mixture  gives  a  blue  colour  to  starch :  such  is  the 
case  with  hydrosulphocyauio  acid  and  its  salts,  and  therefore  also  with 
human  saliva  (L.  Thompson),  morphin  (Serullas),  narcotin,  and  pyro- 
gallic  acid  (Duflos,  Schw,  62,  391). 

Combinations,    a.  With  water. 

^  a.  Hydrates  of  Iodic  Acid.  According  to  Millon  (iT.  Ann.  Chim. 
Phys.  19,  400),  the  crystals  obtained  by  spontaneous  evaporation  of  a 
concentrated  aqueous  solution  [of  iodic  acid  (p.  254)  consist,  not  of  the 
anhydrous  acid,  but  of  iodic  acid  combined  with  1  atom  of  water,  10^ 
HO;  and  these,  when  heated  to  ISO''  (266°  F.),  or  when  digested  in  abso- 
lute alcohol,  are  converted  into  310',  HO,  a  compound  which  is  insoluble  - 
in  alcohol,  but  is  reconverted  into  10',  HO  by  contact  with  water. 
Either  of  these  hydrates  heated  to  1 70""  (338°  F.)  yields  the  anhydrous  acid, 
which,  by  contact  with  water  or  alcohol,  is  converted  into  the  first  hy- 
drate, 10*  HO.     {Comp.  Rammelsberg,  Pogg.  72,  417.)     IT 

j8.  Agueov>s  Iodic  Acid.  The  anhydrous  acid  deliquesces  in  damp 
air  (H.  Davy)  :  according  to  Serullas,  it  is  permanent  in  the  air,  but 
extremely  soluble.  The  solution,  which  is  transparent  and  colourless,  is 
not  altered  by  light ;  it  may  be  evaporated  to  the  consistence  of  a  syrup. 
At  200%  it  is  resolved  into  iodine  and  oxygen  gas  (Gay-Lussac)  :  when 
carefully  evaporated,  it  first  becomes  syrupy,  then  pasty,  and  finally 
loses  all  its  water  without  undergoing  decomposition.  (H.  Davy.)  Sul- 
phuric acid  and  nitric  acid  diminish  the  solvent  power  of  water  upon  iodic 
acid,  and  cause  it  to  separate  in  the  crystalline  form  from  its  concen- 
trated solution.  (Serullas.)  These  crystalline  precipitates  were  regarded 
VOL.  n.  s 


258  IODINE. 

by  Davy  as  intimate  compounds  of  iodic  acid  with  sulphuric  or  nitric 
acid.  SeruUas,  on  the  contrary^  has  shewn  that  the  sulphuric  or  nitric 
acid  is  attached  to  them  merely  by  mechanical  adhesion;  and  that  it  may 
be  almost  entirely  removed  by  washing  with  water  and  pressing  between 
blotting-paper.  Alcohol  likewise  partly  precipitates  iodic  acid  from  its 
aoueoussolution.  (Serullas.)  Aqueous  iodic  acid  communicates  a  blue 
colour  to  starch  or  its  solution  in  boiling  water,  on  the  addition  of  sul- 
phurous acid,  hydrosulphnrio  acid,  protochloride  of  tin^  or  other  deoxi- 
dising agents. 

IT  6.  With  sulphuric  acid. — ^When  iodic  acid  is  digested  in  oil  of 
vitriol  (SO'HO)  nearly  at  the  boiling  pointy  a  white^  pulverulent 


having  a  mother-of-p^rl  lustre,  separates  on  cooling.  No  gas  is  evolved. 
The  composition  of  this  substance  is  3S0»,  HO  -f  I0«,  HO.  With  more 
dilute  acid  (SO^  8H0),  another  compound  is  obtained,  consisting  of 
»{S0>,3H0)  -h  10*,  HO.     (MiUon,  N.  Ann.  Chim.  Fhyt.  12,  330.)     T 

c.  Iodic  acid  combines  with  salifiable  bases,  forming  salts  callea  To- 
dates.  These  compounds  are  obtained  :  1.  By  bringing  iodine  in  con- 
tact with  an  alkali  and  water,  and  removing  the  metallic  iodide  or  hydri- 
odate  formed  at  the  same  time,  by  digestion  in  alcohol. — 2.  By  direct 
mixture  of  iodic  acid  with  a  salifiable  base. — 3.  By  bringing  the  aqueous 
acid  in  contact  with  metals,  which  become  oxidated,  partly  at  the  expense 
of  the  water,  partly  at  the  expense  of  the  acid.  Some  iodates  contain 
one,  some  two,  and  others  three  atoms  of  acid  to  one  atom  of  base. 
When  heated,  these  salts  either  give  up  6  atoms  of  oxysen,  but  no  iodine, 
and  are  converted  into  metallic  iodides  (KO,  10');  or  they  part  with  their 
iodine  and  5  atoms  of  oxygen,  and  are  reduced  to  metallic  oxides  (BaO, 
10'),  accordingly  as  the  metal  has  ffroi^ter  affinity  for  iodine  or  for  oxy* 
gen.  Some  iodates  detonate  when  heated  with  combustible  bodies,  e.  g^ 
on  red-hot  coals, — sometimes  even  when  merely  struck, — ^the  loosely  com- 
bined oxygen  of  the  iodic  acid,  and  sometimes  also  that  of  the  metallic 
oxide  passing  over  to  the  combustible  body^  with  development  of  light 
heat;  but  the  detonation  is  much  weaker  than  that  produced  by  chlorates 
or  nitrates.  The  aqueous  solution  of  an  iodate  mixed  with  sulphurous  acid 
yields  iodine  and  sulphuric  acid,  part  of  which  combines  with  the  base. 
(Qay-Lussac.)  Witn  hydrosulphuric  acid,  the  solution  of  an  iodate 
yields  h^driodio  acid,  water,  sulphur,  and  a  sulphate  (H.  Rose) ;  with 
hjfdriodic  acid,  it  yields  a  metallic  iodide,  iodine,  and  water ;  with  a 
dissolved  iodide  (or  hydriodate),  if  both  compounds  contain  weak  bases, 
{t.g,  oxide  of  zinc,)  or  if  an  acid  is  added  which  takes  hold  of  the  base 
-^the  products  are  water,  a  metallic  oxide,  and  iodine  (Gay-Lussac)  : 
ZnO,  I0«  +  5  (ZnO,  HI)  »  5HO  +  6ZnO  +  61. 

With  hydrochloric  acid  the  iodates  form  water,  a  metallic  chloride, 
terchloride  of  iodine,  and  free  chlorine;  and  the  metallic  chloride  thus 
produced  often  enters  into  combination  with  the  terchloride  of  iodine. 
(Pilhol) : 

KO,IO»  +  6HC1  =  6H0  +  KCl,  +  ICP  +  2C1. 

Arsenious  acid,  with  the  aid  of  heat,  and  likewise  protocUoride  of  tin, 
separate  iodine  from  aqueous  solutions  of  the  iodates.  ^Simon.)  Dilute 
sulphuric  at  a  boiling  heat  separates  the  iodic  acid  from  tnese  salts.  (Gay- 
Lussac.)  When  an  aqueous  solution  of  an  iodate  is  heated  with  nitric 
acid,  that  acid  at  first  takes  hold  of  the  base,  either  wholly  or  in  part ; 
but  when  the  solution  is  evaporated  to  dr^ess  and  more  strongly  heated, 
the  less  volatile  iodic  acid  drives  out  the  nitric  acid,  (Penny,  Ann.  Pharm, 


PERIODIC  ACID.  259 

37,  203.)  Todates  beated  with  strong  faydrochlorio  acid  and  mercary^  or 
with  oil  of  vitriol  and  scale  oxide  of  iron  in  the  state  of  powder,  impart 
a  blue  colour  to  gelatinous  starch,  in  consequence  of  the  separation  of 
iodine  which  takes  place.  (Wackenroder,  N,  Br,  Arch.  24,  148.)  Most 
iodates  are  little  or  not  at  all  soluble  in  water  ;  the  only  salts  of  the  class 
that  are  easily  soluble  are  the  normal  iodates  of  ammonia,  potassa, 
and  soda ;  the  solutions  of  these  salts  give,  with  somewhat  concen- 
trated solutions  of  strontia  and  lime  salts,  and  with  dilute  solutions 
of  baryta,  lead,  and  silver  salts,  a  white,  crystalline-granular  precipi- 
tate. The  silver  precipitate  is  easily  soluble  in  ammonia  (Qay-Lussao) ; 
very  slightly  in  nitric  acid.  (Benckiser.) 

c.  Iodic  acid  is  very  slightly  soluble  in  alcohol.     (SeruUas.) 

D.    Periodic  or  Htperiodio  Acid.  10"'. 

UberiocUaure,  Acide  oxiodiqtie. 

Formaium.  When  chlorine  is  passed  through  a  moderately  warm 
mixture  of  iodate  of  soda  and  caustic  soda,  periodate  of  soda  is  formed, 
and  falls  down  in  the  form  of  powder  when  the  liquid  is  evaporated. 

Freparaitan.  1.  A  solution  of  periodate  of  soda  in  cold  dilute  nitric 
acid  is  precipitated  by  nitrate  of  silver ;  the  yellow  precipitate,  which  is 
bibasic  periodate  of  silver,  is  dissolved  in  hot  dilute  nitric  acid,  and  the 
solution  concentrated  by  evaporation  at  a  moderate  heat,  till  normal 
periodate  of  silver  crystallizes  out.  After  pouring  off  the  mother-liquid, 
which  contains  nitrate  of  silver,  the  normal  periodate  of  silver  is  digested 
in  cold  water,  which  extracts  half  the  acid ;  the  solution  is  then  filtered 
and  evaporated.  (Magnus  &  Ammermiiller.) — 2.  The  soda-salt  is  dis- 
solved in  the  smallest  possible  quantity  of  nitric  acid,  gently  warmed  and 
dilute  ;  the  solution  mixed  with  nitrate  of  lead,  which  precipitates  perio- 
date of  leadj  and  the  precipitate,  after  being  washed  and  diffused  in 
water,  decomposed  by  digestion  with  a  quantity  of  sulphuric  acid,  not 
quite  sufficient  for  its  complete  decomposition.  Any  excess  of  sulphuric 
acid  remains  mixed  with  the  periodic  acid,  and  prevents  its  crystallization : 
excess  of  periodate  of  lead  does  no  harm,  not  imparting  any  lead  to  the 
liquid.  The  liquid  is  merely  decanted  from  the  sulphate  of  lead,  because 
filtering-paper  might  reduce  a  portion  of  the  acid  to  the  state  of  iodic 
acid.  The  solution  evaporated  at  a  gentle  heat  yields  hydrated  crjrstals 
which  lose  their  water  of  crystallization  at  160°  (320''  F.).  (Benckiser.) 

Fropetiies.    White  mass,  fusible  by  heat. 

Calciilation.  Vol. 

I  126  69*23 Vapour  ofiodine    ....  2 

70 56  30-77  Oxygen  gas     7 

10» 182  10000  " 

(I«07  «  2  .  789*75  +  7  .  100  =  2279*50.    Beneliofl.) 

Decompositions.  1 .  According  to  Benckiser,  periodic  acid  when  beated 
te  188°  or  190°  (370*' — 374''  F.)  evolves  oxygen  with  great  rapidity,  and  is 
converted  into  iodic  acid,  which,  when  subjected  te  a  stronger  heat,  is 
resolved  into  oxygen  and  vapour  of  iodine. — 2.  With  hydrochloric  acid, 
periodic  acid  yields  chlorine,  water,  and  iodic  acid.  (Magnus  it  Ammer- 
miiller.) 

s   2 


260  IODINE. 

10?  +  2UCI  ^  I09  +  2H0  +  2a. 
3.  The  a<j[ii60iiB  solation  of  the  acid  ma^  be  boiled  witbont  andergoing 
decomposition.  At  a  moderate  heat,  it  oxidizes  phosphorus,  forming 
phosphoric  oxide  and  phosphoric  acid ;  with  zinc,  it  forms  oxide  of  zinc 
and  iodine ;  with  iron,  ferroso-ferric  oxide  and  iodine ;  with  copper,  iodate 
of  copper;  and  with  mercury,  dinoxide  of  mercury  and  iodine.  Acetic 
acid  and  formic  acid  precipitate  iodine  from  the  solution  on  boiling,  and 
at  the  same  time  form  water  and  carbonic  acid :  the  same  action  is  more 
slowly  produced  by  oxalic  and  tartaric  acid.  Alcohol  and  ether  do  not 
exert  any  decomposing  action.  (Benckiser.) 

CamhincUions.  a.  With  Water.  «.  Crystallized  Periodic  Acid, 
Colourless  crystals,  permanent  in  the  air,  and  appearing  to  be  oblique 
rhombic  prisms.  At  130°  (266°  F.)  they  fuse  without  decomposition;]  and 
on  cooling,  the  acid  solidifies  in  a  crystalline  mass.  (Benckiser.)  0.  The 
acid  is  readily  soluble  in  water,  and  deliquesces  quickly  in  moist  air. 
(Benckiser.) 

5.  With  Salifiable  Bases.  Feriodates,  ffi/periodates,  Oxiodates.  Some 
of  these  salts  are  normal  or  monobasic,  others  bibasic.  The  normal 
salts,  when  heated  to  redness,  evolve  oxygen  gas  and  leave  metallic 
iodides;  the  bibasic  salts  are  resolved  into  a  mixture  of  iodide  and  oxide, 
or  reduced  metal.  Normal  periodate  of  soda  loses  6  atoms  of  oxygen  at 
a  low  red  heat  ^p.  253),  and  the  other  two  at  a  higher  temperature.  The 
periodates  certainly  detonate  with  combustible  bodies.  Most  of  them  are 
difficultly  or  not  at  all  soluble  in  water.  The  solution  of  the  normal  soda- 
salt  precipitates  bibasic  periodates  from  solutions  of  baryta,  lime,  lead, 
and  silver  salts,  while  the  liquid  acquires  an  acid  reaction.  The  silver 
precipitate  is  of  a  light-yellow  colour,  and  when  warmed  with  water,  be- 
comes dark  red.  All  periodates  dissolve  with  tolerable  facility  in  dilute 
nitric  acid.  (Benckiser.) 

c.  Periodic  acid  dissolves  with  tolerable  facility  in  alcohol  and  ether. 

IT  Other  compounds  of  iodine  and  oxygen  have  been  obtained  by 
Millon.  {N,  Ann,  Chim.  Phys.  12,  330;  abstr.  Ann.  Pharm,  52,  236.) 
When  iodine  is  rubbed  up  in  a  mortar  with  nitric  acid  containing  1  or  2 
atoms  of  water,  a  bulky  yellow  powder  is  obtained  which  appears  to  be  a 
compound  of  nitric  acid  with  an  oxide  of  iodine.  In  contact  with  water, 
it  is  immediately  resolved  into  nitric  acid,  iodic  acid,  and  iodine:  the  same 
decomposition  is  brought  about  by  the  aid  of  heat.  If  the  action  of  the  nitric 
acid  be  long  continued,  the  compound  is  wholly  converted  into  iodic  acid. 
By  treating  it  with  dilute  alcohol,  a  small  quantity  of  a  yellow  substance 
is  obtained,  which  appears  to  be  composed  of  10^:  this  substance  Millon 
calls  Hypo-iodic  acid. 

By  heatinff  a  mixture  of  30  parts  iodic  acid  and  150  sulphuric  acid, 
till  a  few  bubbles  of  oxygen  gas  are  given  off,  a  considerable  quantity  of 
a  scaly,  sulphur-yellow  substance  is  formed  in  the  boiling  liquid :  this 
substance  appears  to  consist  of  4lO'  -f  10*  -|-  SO',  HO.  If  the  boiling 
be  continued  for  longer  time,  the  evolution  of  oxygen  goes  on,  and  crystals 
are  formed  bavins  a  much  deeper  yellow  colour  than  the  preceding :  the 
composition  of  these  crystals  appears  to  be  :  2lO*  -h  10*  +  SO^  HO. 
Water  decomposes  both  these  compounds  into  sulphuric  acid,  iodic  acid 
and  iodine. 

By  continuing  the  action  of  the  sulphuric  acid  till  iodine  begins  to 
escape  together  with  the  oxygen,  two  other  compounds  are  obtained,  to 


HTDRIODIC  ACID.  261 

which  Millon  has  assigned  the  formulas  :  10^  -f  280*,  HO  and  PO^'  + 
lOSO*,  HO.  These  substances,  when  subjected  to  the  action  of  moist  air, 
appear  to  yield  the  compounds  10^  and  IH)^'  in  the  separate  state:  to 
the  latter  Millon  gives  the  name  of  Svb^hypoiodic  acid,  IT 

lODINB  AND   HtDROOEN. 

A.    Hydriodous  Acid.    HP, 

lodurelted  Hydriodic  acid,  Acide  hydriodigue  ioduri,  Hydriodiffs  Sdure, 

Formed  when  aqueous  solution  of  hjdriodio  acid  is  brought  in 
contact  with  excess  of  iodine:  when  the  same  solution  is  exposed  to 
the  air,  the  oxygen  of  which  depriyes  the  hydriodic  acid  of  part  of 
its  hydrogen;  also  when  iodine  is  brought  in  contact  with  paper  and 
other  organic  substances,  the  hydrogen  of  which  is  with  some  diffi- 
culty taken  up  by  the  iodine;  and  when  iodine  in  excess  is  brought  in 
contact  with  any  compound  of  hydrogen  which,  with  a  smaller  quantity  of 
iodine,  yields  hydriodic  acid. 

Hydriodous  acid  is  not  known  in  the  separate  state. 

Calculation. 

21  252  99-60 

H  1  0-40 

HI« 253  100-00 

This  composition  is  reduced  from  the  experiments  of  Banp  (J.  Pharm, 
9,  40);  according  to  which  it  appears  that  aqueous  solution  oi  hydriodic 
acid,  or  of  hydriodate  of  potassa,  or  hydriodate  of  oxide  of  zinc,  when 
brought  in  contact  with  iodine,  dissolves  a  quantity  of  it  exactly  equal  to 
that  which  the  solution  itself  already  contains. 

Combinations,  a.  With  Water.  Aqueous  Hydriodous  Acid.  Prepared 
in  the  way  just  mentioned.  Forms  a  dark-brown  liquid  having  the  smell 
of  iodine  and  a  slightly  acid  taste.  When  exposed  for  some  time  to  the  air, 
the  oxygen  of  which  gradually  abstracts  the  hydrogen,  it  deposits  crys- 
tallized iodine.  (Plisson,  Joss,  J.  pr.  Ghem.  1,  135;  Marchand,  Pogg.  31, 
540.) 

6.  With  Salifiable  Bases.    HydriodiUs.  (Vid.  Metallic  Iodides.) 

B.    Hydriodic  Acid.    HI. 

Hydriodsdure,  Bydriod,  lodwasserstoff-sdure,  Acide  hydriodique,  Acide 
iodhydrique;  in  the  gaseous  state  :  Hydriodic  Acid  gas,  Hydriod" 
saures  gas,  ffydriod-gas,  lodwasserstoff-gas,  Oas  acide  hydriodigue^ 
Gas  acide  iodhydrique. 

Formation.  1.  When  hydrogen  gas  and  vapour  of  iodine  are  passed 
together  through  a  red-hot  tube.  (Gay-Lussac.)  According  to  Blundell 
{Pogg.  2,  21 6),  sponoy  platinum  brings  about  the  combination  at  ordinary 
temperatures. — 2.  Next  to  oxygen,  fluorine,  chlorine,  and  bromine,  iodine 
has  of  all  substances  the  greatest  affinity  for  hydro^u,  and  consequently 
abstracts  that  element  from  most  of  its  combinations,  viz.  from  phos- 
phuretted  hydrogen,  hydrosulphuric  acid,  ammonia,  and  man^  organic 
compounds,  e.  g.  alcohol,  ethe^;  and  volatile  oils— the  result  b^ing  in  all 


262  IODINE. 

euefl  tlie  fonnation  of  hydriodio  aoid.  (Gaultier;  Colin.)-^.  Iodine  does 
not  decompose  water^  eren  at  a  red  heatj  or  at  all  events,  produces  mere 
traces  of  iodic  and  hjdriodic  acids.  (Gay-Lnssac.)  If^  however,  there  is 
likewise  present  any  substance  that  can  take  up  the  oxygen  of  the  water, 
hydriodic  acid  is  produced  in  abundance.  Hence  water  and  iodine,  in 
contact  with  phcisphorus,  form  hydriodic  acid  and  phosphorous  acid  (Gfay- 
Lussac):  with  hypophosphorous  acid,  they  form  hydriodic  acid  and  phos- 
phorous acid  (Dulong):  with  sulphurous  acid,  only  however  when  a  con- 
siderable quantity  of  water  is  present,  they  yield  hydriodic  and  sulphuric 
acid;  whereas  if  the  liquid  be  concentrated,  sulphurous  and  hydriodous 
acids  are  produced :  dry  hydriodic  and  sulphurous  acid  gases  have  no 
action  on  each  other.  (Soubeiran,  «7.  Pharm,  13,421.)  With  sulphites, 
if  largely  diluted,  the  products  are  hydriodic  acid  and  a  sulphate ;  simi* 
larly  with  hyposulphites ;  with  arsenious  acid,  hydriodic  acid  and  arsenic 
acid;  with  stannous  salts,  hydriodic  acid  and  a  stannic  salt ;  and  with 
certain  metals,  hydriodio  acid  and  a  metallic  oxide. 

Preparation*  1.  In  ths  gaseoits  state,  a.  1  part  of  phosphorus  and 
9  parts  of  iodine  are  moistened  with  a  small  quantity  of  water  or  aqueous 
hydriodic  acid,  or  covered  with  moistened  glass-powder,  and  heated  in  a 
retort  connected  with  the  mercurial  trough.  Towards  the  end  of  the 
operation,  hydriodate  of  phosphuretted  hydrogen  may  sublime.^-6.  1  part 
of  phosphorus  is  gently  heated  with  14  parts  of  iodide  of  potassium,  20 
of  iodine,  and  a  small  quantity  of  water.  If  the  evolution  of  gas  becomes 
too  violent,  the  vessel  must  be  plunged  into  cold  water ;  if  it  becomes 
too  slow,  heat  must  be  again  applied.  (Millon,  J.  Pharm.  26,  299.) 
2K1  +  51  +  P  +  7H0  =  2KO,  PO*  +  7HI. 

{Vid.  Deville*8  method;  Ann,  Chim.  Phys.  75,  46.^ 

2.  In  the  liquid  state.  Iodine  and  persulphiae  of  hydrogen,  which, 
when  they  come  in  contact,  unite  and  form  a  yellowish-brown  liquid, 
are  placed  together  in  the  closed  end  of  a  dry  glass  tube ;  and  at  a  short 
distance  from  them,  in  a  bend  of  the  tube,  is  placed  a  small  quantity  of 
water.  If  the  tube  be  then  sealed,  and  the  first-mentioned  lianid  brought 
in  contact  with  the  water,  decomposition  takes  place,  resulting  in  the 
separation  of  sulphur  and  hydriodic  acid;  and  a  considerable  portion  of 
the  latter  condenses  in  the  liquid  state.  (Kemp,  Phil.  Mag,  J,  7,  444.) 

3.  In  the  solid  state.  Liquid  hydriodio  acid  solidifies  at  a  temperature 
of  -  51°  C.  =  -  59-8°  F.  (Faraday.  Vid,  L,  287.) 

Properties,  In  the  solid  state,  hydriodic  acid  is  perfectly  transparent 
and  colourless,  and  intersected  with  fissures,  like  ice.  (Faraday.) 

In  the  liquid  state  it  is  yellowish.  (Kemp.)  In  the  gaseous  state  it 
is  colourless.  Sp.  gr.  (I,,  279.)  Reddens  litmus  strongly;  has  a  very  sour 
smell  like  that  of  hyarochloric  acid  gas;  very  suffocating  when  inhaled; 
produces  dense  white  fumes  in  the  air;  does  not  support  combustion,  and 
is  not  itself  combustible. 

Calculation.  Vol.  Sp.gr.     Vol.  Sp.gr. 

I      ...  126  99-21  Vapour  of  Iodine....  1  8-7356  =  i  43678 

H  ....       1  0-79  Hydrogen  gag  1  0-0693  =  \  0*0346 

HI  ....  127  10000  Hydriodic  add  gas .  2  8-8049=  1  4-4024 

(HI  =  6-24  +  789-75  =  795-99.    BerzeUus.) 

De(xmpositions.    1.  A  mixture  of  hydriodic  acid  and  oxygen  gases 


HTDRIODIO  ACID.  26S 

PMsed  through  a  red-hot  porcelain  tube  is  resolved  into  water  and 
iodine.  (Gay-Lassac.) — 2.  The  following  compoundB  give  up  their  oxj" 
gen  to  the  hydrogen  of  the  hjdriodio  acid^  forming  water  and  separating 
iodine.  Hjdrated  peroxide  of  hydrogen  is  conrerted  by  it  into  water. 
(Thenard.) — Sulphurous  acid  gas  and  hjdriodio  acid  gas  yield  wateri 
sulphur,  and  iodine : 

S0«  +  2HI  =  2H0  +  S  +  21. 
If  water  is  present,  the  two  acids  have  no  action  on  one  another.  (Dumas.) 
When  mixed  in  the  state  of  aqueous  solution,  they  form  a  yellow  liquid, 
the  colour  of  which  is  brighter  in  proportion  as  the  acids  are  more  con* 
oentrated.  When  exposed  to  the  air,  it  gradually  becomes  coloured  from 
top  to  bottom,  in  consequence  of  separation  of  iodine :  a  fresh  addition 
of  sulphurous  acid  colours  it  yellow  again;  but  the  colour  becomes  con- 
tinually weaker,  and  at  length  sulphur  is  separated.  (Saladin,  J,  Chim. 
Med.  7,  528.)— Oil  of  vitriol  and  hydriodic  acid  gem  or  concentrated 
solution  of  hydriodic  acid,  yield  iodine,  water,  and  sulphurous  aoid. 
(Gay-Lussao.) 

SO*  +  HI  =  S0«  +  HO  +  I. 
On  the  addition  of  water,  sulphuric  acid  and  hydriodio  acid  are  again 
produced  (reciprocal  affinity,  I.,  128).  JSaubeiran, — Aqueous  iodic  acid 
and  hydriodic  acid  yield  water  and  iodine  {Sch.  76). — Hypochlorous 
acid  decomposes  hydriodic  aoid,  both  in  the  gaseous  form,  and  in  the 
state  of  aqueous  solution.  (Balard.) — ^Nitric  acid  yields  iodine,  water, 
and  nitric  oxide.  (Ghiy-Lussao.) — Salts  of  ferric  oxide  are  converted  by 
hydriodic  acid  into  salts  of  ferrous  oxide,  iodine  being  at  the  same  time 
precipitated.  (Gay-Lussac.) — 3.  Chlorine  gas,  in  small  quantity,  converts 
hydriodic  aoid  gas  into  hydrochloric  acid  and  iodine; 

CI  +  HI  =  HCl  +  I; 
in  larger  quantity,  into  hydrochloric  acid  and  chloride  of  iodine;  e.  g. 

'  4C1  +  HI  =  HCl  +  IC1». 
(Gay-Lussao.)  In  a  similar  manner,  bromine  and  hydriodic  acid  gas 
yield  hydrobromio  acid  gas  and  iodine,  the  action  being  attended  with 
evolution  of  heat.  (Balard.) — 4.  Potassium,  sine,  iron,  mercury,  and 
other  metals,  immersed  in  this  gas,  are  converted  into  iodides,  1  volume 
of  hydrogen  being  at  the  same  time  liberated  from  2  volumes  of  hydriodio 
acid  gas.  (Gay-Lussac.) — 5.  With  most  basic  metallic  oxides,  hydriodic 
acid  forms  water  and  a  metallic  iodide.  Some  of  these  iodides  separate 
immediately;  so  that,  with  the  salts  of  certain  metallic  oxides,  aqueous 
hydriodic  acid  forms  precipitates  consisting  of  metallic  iodides  and  dis- 
tinguished by  the  following  colours :  Oxide  of  bismuth,  brown ;  oxide  of 
lead,  orange-yellow ;  mercurous  oxide,  greeuish-yellow ;  mercuric  oxide, 
scarlet;  oxide  of  silver,  yellowish- white.  Other  metallic  iodides  remain 
dissolved  in  the  liquid,  and  in  that  state  may  be  regarded  as  hydriodates 
of  metallic  oxides.  With  metallic  peroxides,  e,  g,  the  peroxide  of  man- 
ganese or  of  lead,  hydriodic  acid  forms  a  metallic  iodide  (or  hydriodate), 
water,  and  free  iodine ;  «.  g. 

PbO«  +  2HI  =  Fbl  +  2HO  +  I. 

C(mbi7MiwM,  a.  With  Water.  Aq%UMi»  Hydriodic  acidy  Hydriodic 
acid  Water,  loduretted  Hydrogen  Water.  Water  absorbs  hydriodic  acid 
gas  very  rapidly  and  in  large  quantity.  Preparation.  1.  Iodine  is  dis- 
tilled with  phosphorus  and  a  large  quantity  of  water. — 2.  Hydrosulphuric 
acid  gas  is  passed  into  water  in  which  iodine  is  diffused-^-^the  liquid  being 


264  IODINE. 

well  agitated  all  the  whiles-till  the  iodine  has  disappeared  and  the  liquid, 
which  was  brown  at  first,  has  become  colourless :  the  liquid  is  then  filtered 
and  heated  to  commencing  ebullition  in  order  to  expel  the  excess  of 
hjdrosulphuric  acid.  (Gaj-Lussac.)  Since  the  sulphur,  as  it  precipitates, 
enyelopes  the  iodine  which  still  remains  undissolyed,  Le  Rojer  &  Dunias 
recommend  the  process  of  saturating  water  with  iodine— decanting  tbe 
liquid  from  the  undissolved  portion— converting  the  dissolved  iodine  into 
hydriodic  acid  by  means  of  sulphuretted  hydrogen — digesting  in  this 
liquid  a  fresh  portion  of  iodine,  which  dissolves  much  more  abundantly  in 
the  hydriodic  acid  already  produced— decanting  again — once  more  sator- 
ating  with  sulphuretted  hydrogen — again  digesting  with  iodine,  &c.  &c. 
Another  method  is  that  of  Stratingh,  which  consists  in  passing  hydro- 
sulphuric  acid  gas  through  a  solution  of  iodine  in  16  parts  of  alcohol, 
filtering,  diluting  with  32  parts  of  water,  and  freeing  the  product  by 
distillation  from  alcohol  and  excess  of  hydrosulphuric  acid.  The  acid 
prepared  in  this  manner  is  liable,  however,  to  be  mixed  with  a  product 
of  disagreeable  odour,  arising  from  the  action  of  the  hydrosulphuric  acid 
on  the  alcohol. — 3.  Iodide  of  barium  dissolved  in  water  is  exactly  de- 
composed by  the  equivalent  quantity  of  sulphuric  acid,  and  the  product 
separated  by  filtration  from  sulphate  of  baryta.  (Glover,  PhU,  Mag,  J, 
19,  92.) — 4.  Granulated  lead  is  agitated  with  iodine  and  water  till  the 
liquid  becomes  colourless;  hydrosulphuric  a«id  gas  is  then  passed  through, 
and  the  liquid  decanted*  (Joss, «/.  pr,  Chem.  1, 133.)  The  aqueous  solution 
of  the  acid  obtained  by  either  of  these  methods  may  be  concentrated  by 
heating  it  in  a  retort. 

Hydriodic  acid  water  is  colourless;  has  a  specific  gravity  of  1*700 
when  concentrated.  The  concentrated  solution  ooils  between  125®  and 
128®  (257''  and  262'4*>  R),  and  may  be  distilled  over  without  previously 
evolving  gas.  Its  odour  resembles  that  of  the  gas ;  and  its  taste  is  first 
pungent,  afterwards  astringent  and  sour.  When  concentrated,  it  fumes 
on  exposure  to  the  air.  [For  its  decomposition  by  electricity,  vid.  I.,  455.] 
When  exposed  to  the  air,  it  gives  off  hydrogen,  and  is  at  first  quickly 
converted  into  a  brown  solution  of  hydriodous  acid,  which  is  afterwarais 
slowly  and  completely  decomposed,  depositing  beautiful  crystals  of  iodine. 
The  other  modes  of  decomposition  are  given  on  page  263,  2,  3, 5.  A  small 
quantity  of  chlorine  water  turns  it  brownish  red  and  precipitates  iodine; 
a  larger  quantity  decolorizes  it  again.  The  concentrated  solution  is  turned 
yeUow  by  oil  of  vitriol,  and  on  the  application  of  heat,  becomes  brown- 
red,  iodine  being  precipitated  and  iodine  vapour  evolved.  Hydriodic  acid 
water  imparts  a  blue  colour  to  starch  on  the  addition  of  oil  of  vitriol,  or 
of  a  small  quantity  of  chlorine,  or  nitric  acid,  or  chlorate  of  potassa  with 
hydrochloric  acid. 

h.  With  Phosphuretted  Hydrogen. 

c.  With  Salifiable  Bases,  forming  the  Hydriodates:  vid.  Metallic 
Iodides, 

Charcoal  has  no  action  on  iodine,  even  at  a  white  heat.  (H.  Davy.) 
The  compounds  of  iodine  with  carbon  and  hydrogen  together,  will  be 
described  under  Organic  Chemutry, 

Iodine  and  Boron. 

Vapour  of  iodine,  passed  over  an  ignited  mixture  of  charcoal  and 
boracic  acid,  yields  a  small  quantity  of  a  yellow  sublimate,  probably 
Iodide  of  Boron,  (luglis.) 


-1 


IODINE  AND  PHOSPHORUS.  265 

Iodine  and  Phosphorus. 

A.  Iodide  of  Phosphorus.  Combination  takes  place  at  ordinary 
temperatures,  and  according  to  Gazzaniga  (i?t66.  Univ.  54,  186),  even  at 
—24°,  with  great  evolution  of  heat,  which,  if  the  air  has  access  to  the  mate- 
rials, sets  fire  to  the  phosphorus.  (Compare  Traill;  Ed.  Phil,  J.  12,  217; 
also  Ann.  Phil.  24,  153.) 

a.  1  part  of  phoiphorus  with  24  of  iodine.  Black  mass,  fusing  at  46 ^ 
and  forming  a  brown  solution  in  water.  (Does  this  solution  contain  phos- 
phorous and  hydriodous  acids?.) — b.  1  part  of  phosphorus  with  16  of 
todine.  Dark  grej^  crystallized;  fuses  at  29°;  dissolyes  in  water  forming 
phosphorous  and  hydriodic  acid  (perhaps  also  a  small  portion  of  hy- 
driodous  acid  is  formed). — c.  1  part  of  phosphorus  wiUb  8  of  iodine. 
Orange-yellow  mass,  fusing  at  100^^  volatile  at  a  higher  temperature; 
dissolves  in  water,  forming  phosphorous  and  hydriodic  acid,  with  evolution 
of  phosphuretted  hydrogen  and  precipitation  of  flakes  of  phosphorus. 
(Gay-Lussac.) 

B.  Compound  op  Iodic  acid  and  Phosphoric  acid.  The  two  acids 
mixed  together  in  the  state  of  aqueous  solution  form  a  yellow  crystalline 
mass,  which  may  be  sublimed.  (H.  Davy.)  Serullas  doubts  the  existence 
of  this  compound. 

C.  Hydriodate  op  Phosphuretted  Hydrogen.  1 .  When  hydriodic 
acid  gas  and  phosphuretted  hydrogen,  both  dried  as  completely  as  possible, 
are  brought  together  in  a  vessel,  they  unite  and  form  colourless  crystab. 
(Houton  LabiUardi^re,  Ann.  Chim.  Phys.  6,  304;  also  €HXb.  68,  253; 
also  N,  Tr,  3,  1,  189.) — 2.  Phosphorus  and  iodine  in  nearly  equivalent 

>roportions  are  heated  in  a  retort    with   a  small  quantity  of  water ; 
jydriodic  acid  gas  is  first  evolved,  and  afterwards  hydriodate  of  phos- 

Shuretted  hydrogen  sublimes.     Probably^  hypophosphorous  acid  is  pro- 
uced  in  the  first  instance,  and  is  converted,  together  with  the  excess  of 
water,  into  phosphoric  acid  and  phosphuretted  hydrogen : 

2P  +  21  +  5H0  =  PO*  +  PH»,HI  +  HI. 
The  product  actually  obtained  is  however  much  less  than  this  calculation 
would  lead  us  to  expect,  because  the  greater  portion  of  the  hydriodic  acid 
escapes  before  the  decomposition  of  the  hypophosphorous  acid  is  complete. 
Guy-Lussac  first  obtained  in  this  manner  a  white  sublimate  crystallized  in 
cul>es,  and  evolving  phosphuretted  hydrogen  when  put  into  water;  he 
did  not  however  examine  it  further.  Serullas  {J.  pr.  Chem,  8,  6  ;  also 
Schw.  64,  238 ;  also  Pogg.  24,  345)  puts  into  a  retort  4  parts  of  iodine 
and  1  part  of  phosphorus  mixed  with  a  small  quantity  of  coarsly  pounded 
glass  (introducing  the  mixture  through  the  tubulure) — ^moistens  the 
mixture  with  rather  more  than  \  pt.  water,— and  quickly  connects  the 
retort  by  means  of  a  stopper  with  a  glass  tube  cooled  by  wet  linen.  The 
evolution  of  hydriodic  acid  and  hydriodate  of  phosphuretted  hydrogen 
be^ns  immediately,  and  is  kept  up  by  gently  heating  the  retort.  The 
sublimed  compound  is  driven  by  means  of  a  red-hot  coal  from  the  neck  of 
the  retort  into  the  tube,  where  it  collects  in  the  form  of  a  hard  crystalline 
crust.  This  crust  is  detached  from  the  retort  by  means  of  a  sharp  metal 
rod,  and  purified  by  a  second  distillation  in  the  same  apparatus.  The 
quantity  of  the  compound  obtained  is  at  most  equal  to  that  of  the  phos- 
phorus used. — H.  Rose  {Pogg.  24,  151)  heats  in  a  retort  1  part  of 
phosphorus  with  4  parts  of  iodine  and  a  very  small  quantity  of  wafer  (or 


I 


266  IODINE. 

better^  of  aqneonB  hjdriodio  acid)-— passes  the  Taponrs  into  a  long  glass 
tube— -Andy  after  the  whole  of  the  hydriodate  of  phosphuretted  hydrogen 
has  been  driven  into  the  tube  by  the  applioation  of  heat,  detaches  the  tube 
from  the  retort— passes  a  stream  of  air  previously  dried  by  chloride  of 
calcium  through  it^  in  order  to  expel  the  hydriodic  acid  ga*— 4itid  seals  it 
at  both  ends. 

Large,  transparent,  colourless  crystals  having  the  lustre  of  diamond* 
According  to  Gay-Lussac  and  Houton  Labillardiere,  they  form  cubes  ; 
aocordins  to  H.  nose  {Poag,  46,  636),  square  prisms  with  the  terminal 
edges  and  angles  truncated  {Fig,  34).  By  gentle  heating  in  close  reseelB, 
the  crystals  may  be  sublimed  backwards  and  forwards  .without  fusing. 
(H.  Rose.)     Boiling  point,  about  80^.  (Bineau.) 

Calculation.  H.  Rose. 

PH»  34-4  21-31  20-91 

HI     127-0  7869  7009 

PH*,HI    ....161-4  10000  10000 

Acoording  to  Bineau.  Vol.  Sp.  gr. 

PhospliTiretted  Hydrogen  gaa \  0*5962 

Hydriodic  add  gaa   j  2-2012 

Vaponr  of  Hydriodate  of  Phoiphnrettod  Hydrogen  ....  1  2-7974 

Houton  Labillardi^re  distinguishes  two  compounds,  according  as  the 
more  inflammable  or  the  less  inflammable  phosphuretted  hydrogen  lb  used  in 
the  preparation  by  method  1 :  the  compound  exhibits  the  same  properties  in 
both  cases;  but  in  the  former,  it  appears  to  contain  1  vol.  hydriodic  acid 
gas  with  I  vol  of  the  more  inflammable,  and  in  the  latter,  1  vol.  hydriodic 
acid  with  1  vol.  of  the  less  inflammable  gas.  But  H.  Bose  and  Leverrier 
{Ann.  Ghim.  Phys,  60,  192)  have  shown  that  the  more  inflammable  gas 
likewise  combines  with  hydriodic  acid  ga«  in  equal  volumes,  and  that  the 
two  compounds  are  perfectly  identical 

D^oompofUioM.  The  vapour  of  this  compound  may  be  passed,  with- 
out undergoioff  decomposition,  through  a  red-hot  tube  containing  borax 
in  a  state  of  fusion.  (SeruUas.)  According  to  H.  Rose,  the  compound 
deposits  phosphorus  even  when  gently  heated,  and  the  crystals  thereby 
acquire  a  yellowish  tinge.  1.  Water  and  watery  liquids,  such  as  solution 
of  ammonia  or  potassa,  take  up  the  hydriodic  acid  and  liberate  the  phos- 
phuretted hydrogen,  rapidly,  with  efiervescence,  and  in  the  less  inflammable 
state.  (Houton;  H.  Rose.)  Even  concentrated  solution  of  ammonia  almost 
always  liberates  the  gas  in  the  less  inflammable  condition.  ^H.  Rose.) 
When  exposed  to  the  air,  especiallv  to  moist  air,  the  crystals  deliquesce, 
with  evolution  of  phosphuretted  hydrogen. — 2.  Ammoniacal  gas  forms 
hydriodate  of  ammonia,  and  liberates  a  quantity  of  phosphuretted  hydrogen 
e^ual  in  volume  to  the  ammoniacal  gas  absorbed.  ^Houton.) — 3.  Oil  of 
vitriol  decomposes  the  compound  rapidly,  with  simultaneous  evolution  of 
hydros ulphuric  acid  and  sulphurous  acid  gases,  which  mutually  decom- 
pose each  other,  and  separation  of  sulphur,  phosphorus,  and  iodine,— 
while  the  oil  of  vitriol  retains  in  solution  an  acid  of  phosphorus,  and 
likewise  a  portion  of  hydriodic  acid  still  in  a  state  of  decomposition. 
4.  Iodic,  bromic,  chloric,  and  nitric  acids,  and  the  anhydrous  salts  of  the 
first  three,  set  fire  to  hydriodate  of  phosphuretted  hydrogen  at  ordinary 
temperatures.  Nitrate  of  silver  exerts  a  violent  action,  producing  great 
rise  of  temperature  and  forming  iodide  and  phosphate  of  silver.  Per* 
chloric  acid,  perchlorate  of  potassa^  and  nitre  decompose  the  compound 


IODINE  AND  SULPHUR.  067 

onl^when  heat  is  applied,  and  eTen  then  bat  slowly.  (Serollas.)-*^. 
Oxide  of  silver  in  contact  with  this  compound  prodnces  great  deyelopment 
of  heat  and  is  converted  into  iodide  of  silver,  with  evolation  of  spon- 
taneously inflammable  phosphuretted  hydroffen  gas.  Protobromide  of 
mercury  produces  iodide  of  mercury  and  hydrobromate  of  phosphuretted 
hydrogen,  with  which  however  a  quantity  of  hydriodate  of  phosphuretted 
hydrogen  still  remains  mixed.  Protochloride  of  mercury  yields  iodide  of 
mercury,  hydrochloric  acid  gas,  and  phosphuretted  hydrogen.  Cyanide  of 
mercuiy  or  cyanide  of  potassium  yields  a  metallic  iodide,  hyorooyanio 
acid,  and  phosphuretted  hydrogen  gas*  (Serullas.) — 6.  With  hot  absolute 
alcohol,  the  compound  yields  hydriodic  ether  and  phosphuretted  hydrogen 
gas.  It  is  also  decomposed  by  contact  ii^ith  sulpnovinate  of  oil  of  wine. 
(Serullas.)  Hydriodate  of  phosphuretted  hydrogen  is  not  decomposed  by 
oxygen,  carbonic  acid,  hydrosnl|phuric  acid,  or  hydrochloric  acid  gas,  or  by 
mercury  (Houton);  neither  is  it  decomposed  by  hot  glacial  acetic  acid. 
(Serullas.) 

loDiKB  Ain>  Sulphur. 

A.  loDiDV  OF  SuLPHTTB. — 1.  Sulphur  combines  with  iodine  on  the 
application  of  heat,  even  underwater,  and  with  slight  rise  of  temperature. 
(Oay-Lussac.) — 2.  Aqueous  hydriodic  acid  mixed  with  chloride  of  sulphur 
yields  hydrochloric  acid  anfd  a  precipitate  of  iodine.  (Inglis.)  From  aque- 
ous solution  of  terchloride  of  iodine,  hydrosulphuric  acid  throws  down  a 
cinnabar-coloured  precipitate  of  iodide  of  sulphur.  (Grosourdy,  J,  Chim, 
Med.  9,  429.) 

The  compounds  obtained  by  method  (1)  are  blackish-grey,  brilliant, 
and  exhibit  a  radiated  fracture  like  that  of  crude  sulphide  of  antimony  j 
they  fuse  below  60°.  (Gay-Lussac.)  When  heated  out  of  contact  of  air, 
they  evolve  pure  vapour  of  iodine,  according  to  Gay-Lussac ;  but  accord- 
ing to  H.  Rose  {Pogg,  27,  115),  they  give  off  an  iodide  of  sulphur  con- 
taining 11*24  percent,  of  sulphur.  They  are  not  soluble  in  water.  (Gay- 
Lussac.^  Alcohol,  in  a  few  minutes,  extracts  the  whole  of  the  iodine  from 
them.  (Inglis.) 

One  part  of  sulphur  to  9  parts  of  iodine :  smells  faintly  of  iodine. — 
1  part  (1  At.)  sulphur  to  7 '9  parts  (1  At.)  iodine:  Blackish-grey;  of 
lamellated  and  radiated  texture;  smells  faintly  of  iodine. — 1  part  (2  At.) 
sulphur  to  4  parts  (1  At.)  iodine  :  Decidedly  crystalline. — 1  part  sulphur 
to  1  or  i  part  iodine  f  somewhat  dense  masses,  which  turn  white  on  expo- 
sure to  the  air.  (N.  E.  Henry,  J.  Pharm,  13,  403.) 

B.  Sulphate  of  Iodine.  —  Anhydrous  sulphuric  acid  forms  a 
greenish-blue  liquid  with  iodine.  (Bussy.)  According  to  Fischer  {Pogg. 
16,  121),  the  compound  is  sometimes  brown,  sometimes  green,  sometimes 
blue ;  the  gi^en  and  blue  colours  are  transient ;  the  brown,  persistent. — 
With  the  minimum  quantity  of  sulphuric  acid,  the  compound  is  brown ; 
with  a  larger  quantity,  blue;  and  with  a  still  larger  quantity,  green. 
(Wach.)  If  a  bent  glass  tube  containing  1  part  of  iodine  in  one  arm,  and 
10  parts  of  anhydrous  sulphuric  acid  in  the  other  be  sealed,  and  heat 
applied  to  the  arm  containing  the  stilphuric  acid,  the  portions  of  sulphuric 
acid  vapour  which  first  pass  over,  form  with  the  iodine  a  viscid  brown 
liquid,  which,  by  taking  up  the  rest  of  the  acid,  is  subsequently  converted 
into  a  crystalline  mass  of  a  beautiful  green  colour.  This  substance  melts 
at  d?"*  to  an  oily  liquid^  m^  solidifies  at  )2-d''  ia  bundles  of  fibres.    It 


268  IODINE. 

boilB  in  the  sealed  tabe  at  1 07*5^  salpharic  acid  distilling  over^  and — ^if  the 
other  ann  of  the  tabe  is  immersed  in  a  freezing  mixture— condensing  in 
it  as  a  white  crystalline  mass :  and  the  liquid,  as  it  parts  with  the  acid, 
becomes  first  blue  and  afterwards  brown.  Finally,  iodine  sublimes  and 
crystallizes  on  the  solidified  sulphuric  acid,  and  by  the  application  of  he&t 
may  be  made  to  recombine  with  it,  and  form  the  green  compound.  Oae 
part  of  iodine  and  1 5  of  sulphuric  acid  likewise  form  a  beautiful  green 
compound,  which  behaves  in  a  similar  manner  when  distilled.  If  one  arm 
of  the  tube  contains  1  part  of  iodine  and  1  part  of  sulphur,  the  other,  20 
parts  of  anhydrous  sulphuric  acid,  and  the  whole  is  left  to  stand  over  night 
at  the  ordinary  temperature  of  the  air,  the  sulphur  acquires  a  carmine 
colour.  If  the  sulphuric  acid  arm  be  warmed,  while  the  other  arm  is  kept 
in  a  freezing  mixture,  the  sulphur  and  iodine  form  a  thin  red-brown  liquid, 
which  moves  about  as  if  it  were  boiling,  and  gradually  becomes,  first 
brown,  then  brownish-green^  and  crystaUizes.  When  taken  out  of  the 
freezing  mixture,  it  changes  in  the  course  of  four  weeks  to  a  beautiful 
green  Uquid  (probably  consisting  of  sulphate  of  iodine  with  sulphurous 
acid),  which  crystallizes  in  the  cold.  Sulphurous  acid  may  be  distilled  from 
it,  but  when  separated  in  this  manner,  may  be  made  to  recombine  with 
the  residue.  (Wvuih,  Schw,  50,37.)  From  a  solution  in  hot  dilate  sol- 
phuric  acid,  iodine  crystallizes  in  needles  on  cooling. 

C.  Sulphate  of  Hydriodig  Acid.  Anhydrous  sulphuric  acid 
rapidly  absorbs  hydriodic  acid  gas,  and  deliquesces  with  it  to  a  brown-red 
liquid.     (Aim6,  J.  Pharm.  21,  88;  also  J.  pr.  Ckem.  6,  79.) 

D.  loDURETTED  Persulphide  OP  Hydrogen.  Dry  iodine  dissolves 
in  persulphide  of  hydrogen,  forming  a  liquid  of  a  yellowish-brown  colour. 
The  smallest  quantity  of  water  resolves  the  compound  into  sulphur  and 
hydriodic  acid  (p.  236).  Kemp. 

E.  loDURETTED  BISULPHIDE  OF  Carbon.  lodiuc  dlssolves  abun- 
dantly in  bisulphide  of  carbon,  imparting  a  deep  amethyst  colour  to  the 
liquid;  even  0*001  iodine  produces  a  sensible  amethyst  tmt,  and  t^.-ytht  ^ 
pale  rose-colour.  (Lampadius,  Gilb.  58, 443,  and  Schw.  31,  253.)  A  very 
large  quantity  of  iodine  mtdces  the  compound  black-brown,  and  of  a 
thick  oily  consistence ;  water  shaken  up  with  it  acquires  a  pale  violet 
tint,  but  remains  clear,  and  does  not  take  up  hydriodic  acid.  (Zeise,  Sehto, 
36,  63.)  A  solution  saturated  while  hot  deposits  iodine  on  cooling;  it 
does  not  conduct  electricity.    (Solly,  Fkil,  Mag,  J.  8,  132.) 


Iodine  and  Selenium. 

Iodide  of  Selenium.  The  two  substances  heated  together  in  equiva- 
lent proportions  readily  fuse  into  a  black-grey  mass,  from  which  absolute 
alcohol  abstracts  the  whole  of  the  iodine.  (Trommsdorff,  N.  Tr.  \2, 
2,  45.) 

Other  Compounds  of  Iodine. 

A.  With  Bromine.  — B.  With  Chlorine.  — C.  With  Nitrogen.— 
D.  With  Ammonia. 

S.  With  metals,  forming  the  MetalUo  Iodides.     These  compounds  are 


METALLIC  IODIDES.  269 

formed. — 1.  When  iodine  comes  in  contact  with  a  metal — ^freqnentlj  even 
at  ordinaxy  temperatures^  as  in  the  case  of  mercury.  The  combination  is 
attended  with  development  of  heat,  sometimes  with  flame,  which  is  coloured 
Tiolet  bj  the  iodine  vapour  (e.  g.  potassium,  sodium). — 2.  When  hjdriodic 
acid  comes  in  contact  with  metals  whose  affinity  for  iodine  exceeds 
that  of  hydrogen. — 3.  When  vapour  of  iodine  is  passed  through  a  red-hot 
tube  containing  a  metallic  oxide,  the  metal  of  which  (potassium,  sodium, 
lead  or  bismuth)  has  a  stronger  affinity  for  iodine  than  for  oxygen — in 
which  case,  the  oxygen  is  expelled  in  the  form  of  gas.— 4.  When  hydri- 
odic  acid  is  brought  m  contact  with  metallic  oxides;  in  which  case,  some- 
times at  ordinary  temperatures  (oxide  of  lead),  sometimes  by  crystalliza- 
tion (potassa),  sometimes  on  the  application  of  heat  (oxide  of  zinc),  an 
anhydrous  metallic  iodide  and  water  are  produced. 

All  iodides  are  destitute  of  metallic  lustre;  some  of  them  are  very 
beautifully  coloured.  Their  specific  gravity  is  often  lower  than  the  mean 
specific  gravity  of  their  constituents :  such  is  the  case  with  the  iodides  of 
potassium,  lead,  copper,  and  silver.  (Boullay.) 

But  few  metallic  iodides  are  decomposed  by  heat  alone ;  the  iodides 
of  gold,  silver,  platinum,  and  palladium,  however,  give  up  their  iodine 
when  heated.  Most  metallic  iodides  when  ignited  in  open  vessels,  so  that 
the  air  has  access  to  them,  give  up  their  iodine,  and  are  converted  into 
oxides ;  such,  however,  is  not  the  case  with  the  iodides  of  potassium, 
sodium,  bismuth,  and  lead.  Chlorine,  at  a  red  heat,  decomposes  the  me- 
tallic iodides,  converting  them  into  chlorides,  and  either  setting  the  iodine 
free  or  forming  chloride  of  iodine.  (H.  Davy.)  Bromine  acts  in  a  similar 
manner.  Chlorine-water  likewise  liberates  the  iodine.  Hydrochloric  acid 
gas  decomposes  metallic  iodides  at  a  red  heat,  forming  hjdriodic  acid  fi;as 
and  a  metallic  chloride.  Concentrated  sulphuric  and  nitric  acid,  and  like- 
wise bisulphate  of  potassa,  decompose  all  metallic  iodides  on  the  applica- 
tion of  heat,  the  products  being  iodine,  which  escapes  in  violet  vapours 
(which  give  a  blue  colour  to  paper  moistened  with  starch),  and  a  sulphate 
or  nitrate  of  the  corresponding  metallic  oxide.  When  this  change  is  pro- 
duced by  nitric  acid,  hyponitric  acid  is  formed  at  the  same  time ;  sul- 
phuric acid  and  bisulphate  of  potassa  evolve  sulphurous  acid,  some- 
times, also,  sulphuretted  hydrogen.  Oil  of  vitriol  or  oisulphate  of  potassa 
with  peroxide  of  manganese,  peroxide  of  lead,  or  chromate  of  potassa 
produces  the  same  decomposition,  but  without  evolution  of  sulphurous  acid 
(p.  264.).  A  bead  of  microcosmic  salt  saturated  with  oxide  of  copper  com- 
municates a  beautiful  green  colour  to  the  blow-pipe  flame  on  the  addition 
of  a  metallic  iodide.  (Berzelius.)  Metallic  iodides  agitated  with  oil  of 
vitriol  and  bisulphide  of  carbon,  communicate  an  amethyst-red  tint  to  the 
latter. 

Very  few  metallic  iodides  remain  unaltered  in  contact  with  water: 
such,  however,  is  the  case  with  the  iodides  of  bismuth,  lead,  copper,  and 
several  of  the  noble  metals.  Some  of  them  are  converted  by  water  into 
an  oxide  which  is  precipitated,  and  hydriodic  acid  which  dissolves  in  the 
water  (iodide  of  tin)  :  or  into  a  precipitated  compound  of  iodide  and  oxide 
of  the  metal,  and  a  solution  of  the  iodide  in  aqueous  hydriodic  acid  (the 
iodides  of  antimony  and  tellurium).  Most  metallic  iodides  are  perfectly 
soluble  in  water;  and  the  solution  may  be  regarded  as  containing  either 
the  unaltered  iodide,  or  a  hydriodate  of  the  oxide  formed  by  double  decom- 
position (f.  g.  the  iodides  of  the  alkali-metals,  iron,  nickel,  cobalt,  &c.). 

Aqiieous  Metallic  Iodides  or  Salts  of  Hydriodic  Acid,  Hydriodates,  lodky^ 
drates,  including  Hydriodate  of  Ammonia.     These  compounds  are  pro- 


270  TODINB. 

daoed  on  diasolTing  a  meUllie  iodide  in  water,  on  bring^  iodine  in  oon- 
taot  witli  a  metal  and  water,  or  on  digesting  a  metal  or  metallic  oxide  in 
aaneona  hydriodio  acid:    in  the  latter  case,  hydrogen  gas  is  erolved. 
These  oomponnds  are  extremely  poisonoas.    When  evaporated  ont  of  oon* 
tact  of  air,  they  generally  ieaye  anhydrous  metallic  iodides,  which  partly^ 
separate  in  the  crystalline  form  before  the  water  is  wholly  driven  o£ 
The  earthy  hydriodates,  however,  are  resolved,  on  evaporation,  into  ih« 
earthy  oxides  and  hydriodic  acid,  which  escapes.     A  very  small  quantity 
of  chlorine  colours  the  solution  yellow  or  brown,  by  partial  deoompoeition 
and  formation  of  a  salt  of  hydriodous  acid ;  a  somewhat  larger  quantity 
takes  up  the  whole  of  the  metal,  forming  a  chloride  (or  hydrochlorate),  aad 
separates  the  iodine,  which  then  gives  a  blue  colour  with  starch ;  a  still 
larger  quantity  of  chlorine  gives  the  liquid  a  paler  colour,  and  converts 
the  separated  iodine  into  terchloride  of  iodine,  which  does  not  ffive  a  blue 
colour  with  starch,  and  frequently  enters  into  combination  wim  the  chlo- 
ride produced.    Oil  of  vitriol  and  somewhat  concentrated  nitric  acid  colour 
the  solution  yellow  or  brown,  from  formation  of  hydriodous  acid;  and  if  the 
quantity  of  the  iodide  is  large,  and  the  solution  much  oonoentrated  or 
heated,  they  separate  iodine,  which  partly  escapes  in  violet  vapours. 
Starch  mixed  with  the  solution,  even  if  it  be  very  dilute,  is  turned  blue- 
permanently,  when  the  decomposition  is  effected  by  sulphuric  acid;  for  a 
time  only,  when  it  is  effected  by  nitric  acid,  especially  if  that  acid  be  added 
in  large  Quantity.     If  the  oil  of  vitriol  contains  sulphurous  acid,  which  is 
very  likely  to  lie  the  case  with  fuming  oil  of  vitriol,  it  does  not  prodnoe 
the  blue  colour,  even  when  added  in  large  excess.     If  a  liquid  in  which 
iodine  is  present  (urine,  for  example)  contains  much  organic  matter,  which 
may  decompose  the  oil  of  vitriol  and  form  sulphurous  acid,  it  will  not  pro- 
duce the  blue  colour  with  starch  and  oil  of  vitriol  unless  it  be  diluted  with 
water.  (Dupasquier,  J.  Pharm,  28,  218.)     If  the  solution  likewise  contains 
a  salt  of  iodic  acid,  most  acids  when  mixed  with  it  produce  a  brown  colour 
and  separate  iodine;  because,  by  virtue  of  their  affinity  for  the  base  of  the 
iodate,  they  facilitate  the  mutual  decomposition  of  the  hydriodic  and  iodic 
acid.    The  separation  of  iodine  and  the  blueing  of  the  starch  likewise  takee 
place  on  adding  hydrochloric  acid  to  the  solution,  together  with  a  stannic, 
ferric,  or  cnprio  salt,  or  a  salt  of  chromic  acid.   Also,  if  the  solution  of  the 
iodide  be  covered  with  gelatinous  starch,  the  negative  pole  of  a  small 
voltaic  battery  immersed  in  the  former,  and  the  positive  pole  in  the  latter, 
the  starch  is  turned  blue  in  the  neighbourhood  of  the  positive  wire,  even 
if  the  solution  contains  a  much  larger  quantity  of  bromide  or  chloride  than 
of  iodide.  (Steinberg,  J.  pr.  Ohem.  25,  288.)     If  the  aqueous  solution  of  a 
metallic  iodide  contains  only  y^.^Tnr  P^'^  o/ iodine,  it  gives  a  strong  blue 
colour  with  dilute  gelatinous  starch,  on  the  addition  of  aqua-regia :  with 
T?ro\iroTr  P"^*  ^^  iodine,  the  precipitate  is  violet;    with  -rs^^inrsy  "^se- 
coloured;  and  with  Tq'o,o90f  ^  P^^®  rose-colour  is  produced  after  the  lapse 
of  a  few  hours.  (Harting,  J.  pr.  Chem,  22,  46.)     If  the  solution  likewise 
eontains  a  large  quantity  of  metallic  chloride,  the  blueing  of  the  starch  is 
not  readily  produced  by  the  addition  of  nitric  acid,  in  consequence  of  the 
formation  of  chloride  of  iodine ;  in  this  case,  a  solution  of  starch  in  boilinff 
dilute  sulphuric  acid  ma^  be  added  to  the  solution  of  the  hydriodate,  and 
then  a  very  small  quantity  of  chlorine  water,  the  liquid  ming  stirred  at 
the  same  time.  (Berzelius.) 

The  aqueous  solution  of  a  hydriodate  gives  a  brown  precipitate  with 
salts  of  bismuth;  orange-yellow  with  lead-salts;  dirty  white  with  cuprous 
salts,  and  also  with  cupric  salts,  especially  on  the  addition  of  sulphurous 


t* 


BR0M1KB.  271 

I  acid;  greenish-yellow  with  mercorouisalti;  soarlet  with  meronrio  salts; 

□  yellowish  white  with  silrer  salts;  lemon-yellow  with  gold  salts;  brown 

with  platinio  salts>  firsts  however,  turning  the  liquid  dark  brown-red ;  and 
black  with  palladious  «Jts,  even  when  extremely  dilute.  All  these  pre- 
cipitates consist  of  metallic  iodides;  many  of  them  are  soluble  in  excess 
of  the  hydriodate;  the  silver  precipitate  is  insoluble  in  nitric  acid  and 
ammonia. 

When  iodine  is  digested  in  an  aqueous  solution  of  a  salt  of  hydriodic 
acid,  the  liquid  takes  up  a  {quantity  of  iodine  equal  to  that  which  it  already 
contains.  It  thereby  acquires  a  dark  red-brown  colour,  and  may  then  be 
regarded  as  a  solution  either  of  a  MetaUie  Poly-iodide^  or  of  a  aydrtodite 
or  Salt  of  ffydriodoui  acid.  But  the  affinity  by  which  excess  of  iodine  is 
retained  is  very  feeble. 

Many  metallic  iodides  absorb  ammonia  in  definite  proportions. 

Some  of  these  compounds  unite  with  the  oxides  of  the  corresponding 
metals,  forming  Oxiodidei  or  OxiodureU  (antimony,  tellurium). 

Metallic  iodides  combine  with  one  another:  these  compounds  may, 
according  to  Bonsdorft's  view,  be  regarded  as  lodins-ioUs  (p.  9). 

£.  Iodine  likewise  combines  with  several  organic  snbetances,  as  starcb 
alcohol,  ether,  oils,  cyanogen,  &o. 


Chapter  IX. 

BROMINE. 


Bromine  in  general : 

Balard.    Ann.  Ckim.  Phy$.  32,  337;  also  Schw,  48,  01;  Pogg,  8,  114, 

319  and  461 ;   N.  Tr.  14,  1,  80;  KoHn.  Arch.  9,  231.— Further  : 

Bibl,  Univ.  58,  372 ;  also  J.pr.  Chem.  4,  165. 
Liebig.     Schw.  48,  106;  49,  102. 
A.  Vogel.     Kastn.  Arch.  10,  119. 
L6wig.     Dae  Brom  und  seine  diemischen  VerhaUniue,     Heidelberg,  1829. 

Further:    Mag.  Pharm.  23,   11;  33,  6.— Also:  Pogg.   14,  485.*- 

Also:  Repert.  29,  261. 
De  la  Riye.    Ann.  Chim.  Phy$.  35, 160 ;  also  Pogg.  10,  307;  also  Koitn. 

Arch.  11,  387. 
Berzelius.    Pogg,  14,  164. 

Sources  of  Bromine: 

Asehoff.  -y.  Tr.  15, 1,186.— Berthier.  Ann.  Chm.  Phys.  77,  417;  79, 
164. — Bley.  Br.  Arch.  25,  67.-— Boussinffault.  Ann.  Chim.  Phys. 
54,  163.— Brandos.  Br.  Areh.  20,  145.— Daubeny.  PhU.  Mag.  J. 
6,  323.— DesfoBses.  J.  Pharm.  13,  252  and  533.— Emmet.  SUU 
Amer.  J.  18,  260.— Ficinus.  Kaetn.  Arch.  10,  61 ;  J.  pr.  Chem. 
10,  192.— Fromherz.  Schw.  48,  853.— Fuchs  &  Fikentscher.  J.  pr. 
Chem.  5,  321.— Geiger.  Mag.  Pharm.  16,  207;  17,  57.— C.  G. 
Gmelin.  Kastn.  Arch.  10,  59.— Hayes.  SiU.  Amer.  J.  20,  161.— 
Hermbstadt.    Pogg.  B,  476;  10>  627.<^Hennann.  Schw.  49, 101.— 


272  BROBflNE. 

Von  Holger.  Zdtschr.  Fkys.  Math.  9,  75.— Jonas.  Br.  Arch.  21, 
45;  Ann.  Fharm.  26,  346.— Kastner.  Kcutn.  Arch.  9,  383;  12, 
256.— Kersten.  Schw.  49,  490.— Liebig.  Earin.  Arch.  9,  256; 
Ann.  Fharm,  41,  145.— Ludwig.  ZeiUchr.  Phys.  Math.  2,  417. — 
Meissner.  Schw.  48, 108.  Berl.  Jahrb.  29, 1,  102.— Menzel  &  Coch- 
ler.  Kastn.  Arch.  12,  252;  13,  336.— Merk.  F^[>eH.  81,  454. — 
Mettenheimer.  Schw.  49,  103. — Morin.  J.  Fharm.  27,  84. — Pleischl. 
ZeiUchr.  Fhy$.  v.  W.  4,  93.— Ragazzini.  J.  Chim.  Med.  11,  360. — 
Sarphati.  Repert.  59,  314.— Scharf.  J.  pr.  Chem.  10,  3.— Sp^cx. 
i'o^^.10,510.— Stromeyer.  KaUn.  Arch.  lOy  111.  Schw.  49,249.— 
Toroeiewicz.  Reperi.  34,  8;  36,  169. — Tiinnermann.  Sckw,  49,  249. 
—A.  Vogel.  Kastn.  Arch.  9,  378.— Walchner.  Mag.  Fharm.  17, 
56.— Wdhler  &  Kindt.     Fogg.  10,  509. 

Bramic  Acid:  Serulias.  Ann.  Chim.  Fhya.  45,  203.^— Rammelsbeig. 
Fogg.  52,  79;  55,  63;  abetr.  J.  pr.  Chem.  22,  364;  25,  225. 

Bromide  of  Phosphorus :  H.  Rose.     Fogg.  28,  550. 

HydrcbromUe  of  Fhosphuretted  Hydrogen :  Sernllas.  Ann.  Chim.  Fhys. 
48,  91;  also  J.  Chim.  Med.  8,  1;  also  Schw.  64,  238;  also  Fogg. 
24,  344. 

Bromide  of  Sulphur:  H.  Rose.     Fogg.  27,  111. 

Bromide  of  Selenium :  Serullas.  Ann.  Chim.  Fhys.  35,  349 ;  also  iVT.  Tr. 
16,  2,  197;  abstr.  Fogg.  10,  622. 

Metallic  Bromides:  Serullas.  Ann.  Chim.  Fhys.  38,  318;  also  iiT.  Tr. 
18,  2,  170;  abstr.  Fogg.  14,  111.— 0.  Henry.  J.  Fharm.  15,  49; 
9^&oN.  Tr.  20,  1,  165;  also  Kastn.  Arch.  16,  138.— Berthemot. 
Ann.  Chim.  Fhys.  44,  382;  also  J.  Fharm.  16,  648;  also  Br.  Arch. 
37,  322. 


Brcm,  Brome,  Bromum. — From  Pp^fMs,  an  offensiye  odonr. 

History.  Discovered  by  Balard  in  1826,  in  the  mother-liqnor  of  sea 
water,  and  examined  by  himself  and  by  Lowig  and  Serullas  in  its  most 
important  chemical  relations  or  properties. 

Sources.  As  bromide  of  silver  in  Mexico,  Chili,  and  at  Huelgoeth  in 
Brittany.  (Berthier.)  In  Silesian  zinc  ore,  in  very  small  quantity.  (Men- 
zel &  Cochler.)  In  English  rock  salt,  in  very  small  quantity.  (J.  Chim. 
Med.  17,  131.) 

In  the  following  salt  springs,  probably  in  combination  with  sodium, 
calcium,  or  magnesium :  A  salt  spring  in  the  Eastern  Pyrenees  (Balard). 
-—At  Bex  in  Switzerland  (Morin). — ^lins  in  the  department  of  the  Jura 
(3840  parts  of  the  mother-liquor  contain  one  part  of  bromine)  (Desfosses^. 
— Rehme  near  Minden  (Asohoflf). — Werl  in  the  Duchy  of  Westphalia 
(Kersten). — Liineburg,  Pyrmont;  in  the  salt  found  at  Helden,  Siilbeck,  and 
Salzgitter  (Stromeyer).— Salzuffeln  (Brandes).— Schonebeck  (Hermann). 
—Halle  on  the  &\\e  and  Kdsen  (Meissner). — Diirrenberg  (Meissner, 
Scharf). — Kissincen  (Fuchs&  Fikentscher). — Nauheim  (Tiinnermann). — 
Kreuznach  (Liebig);  1000  parts  of  the  mother-licjuor  contain  0*837 
parts  of  bromine  (Mettenheimer). — ^Rappenau  (Geiger,  Fromherz). — 
Wimpfen  (Fromherz,  Kastner).— Offenau  and  Jaxtfeld  (Fromherz).- — 
Diirrheim  (Fromherz,  Walchner). — Rosenheim  (A.  Vogel). — Halle  in 
the  Tyrol  (Ludwig). — Capo  d'Istria  (Meissner). — Drohobycz  and 
Starozol  in  Gallioia  (Torosiewicz).^Kenahwa  in  North  America  (Em- 


BROMINE.  273 

met). — Hingham  in  North  America  (Hayes). — Several  salt  springs  in 
the  province  of  Antioqnia  in  New  Granada  (Boussingault). — Many  spe- 
cimens of  sal-ammoniac  contain  bromine  (Merk;  Geiger);  probably  be- 
caose  it  has  been  prepared  from  the  mother-liquor  of  mineral  waters  con- 
taining that  element. 

The  following  mineral  waters  likewise  contain  bromine :  Thermal 
springs  of  Albano  (Ragazzini). — Spring  of  Bourbonne  (Desfosses).— 
Beringer  baths  in  the  Harz  (Bley). — ^Ragozy  spring  at  Kissingen 
(Picinns). — Wiesbaden  (nncertam).  Kastner, — Homburg  (Liebig).— 
Karlsbad  (Pleischl). — Magnesia  spring  of  Plillna  (Ficinus). — Goitre- 
water  {KropfwoMer)  of  Hall  in  Austria  (Holger). 

Sea-water  containing  bromine  :  The  water  of  the  Mediterranean 
(Balard). — Searwater  from  the  Gulf  of  Trieste  (Specz). — From  the  North 
Sea  (Stromeyer). — From  the  Baltic  (Wohler  &  Kindt,  Kastner). — One 
gallon  of  sea-water,  near  Marseilles,  contains  1*26  grains,  and  the  same 
quantity  near  Naples  or  from  the  Channel  contains  0*915  grains  of  bro- 
mine (Daubeny). — The  water  of  the  Dead  Sea  also  contains  bromine. 
(C.  G.  Gmelin;  Hermstadt). — All  marine  plants  of  the  Mediterranean,  and 
likewise  varec,  contain  bromine  (Balard). — Bromine  is  also  found  in 
marine  plants  on  the  coast  of  Holland  (Sarphati). — It  is  likewise  present 
in  marine  animals;  namely,  in  Janthina  violacea  (Balard);  in  many 
varieties  of  RhizosUma  and  Gyana^  in  Asterias  ^rubens,  Crognon  wlgare, 
MytUvs  edultSf  and  Pleuronectet  FUsus,  in  which  bromine  is  far  more 
abundant  than  iodine  (Sarphati);  in  sponge  (Hermbstadt,  Jonas);  and  in 
sponge-stone  (Hermbstadt).— Salted  Scotch  herrings  likewise  contain 
bromine.  (Jonas.) 

Preparaiion,  1.  The  mother-liquor  of  sea-water  (or  some  other  water 
containing  bromine)  is  freed,  b^  evaporation,  from  crystallizable  salts, 
and  chlorine  fas  passed  through  it,  as  long  as  the  yellow  colour  increases 
in  depth.  The  chlorine  decomposes  the  metfdlic  bromide  into  chloride 
and  free  bromine,  (or  the  hydrobromate  into  hydrochlorate  and  free 
bromine),  the  latter  produces  the  colour:  an  excess  of  chlorine  would 
convert  the  bromine  into  chloride  of  bromine,  and  thereby  decolorize  the 
liquid ;  it  must  therefore  be  avoided.  The  mixture  is  afterwards  shaken 
with  ether,  which  acquires  a  hyacinth- red  colour  by  absorbing  the  bro- 
mine, the  ethereal  solution  separated  by  decantation  (or  by  means  of  a 
funnel),  and  the  bromine  removed  by  a  concentrated  aqueous  solution  of 
potash  (the  ether  maj  be  used  again  to  treat  the  same  or  a  fresh  solution). 
The  solution  containmg  bromide  of  potassium  and  bromate  of  potassa  is 
then  evaporated  to  dryness,  the  residue  ignited  to  decompose  the  bromide 
of  carbon  which  is  formed  at  the  same  time*  (Lowig)',  the  ignited  mass 
mixed  with  (^  its  weight,  Lowig)  peroxide  ot  manganese,  and  distilled 
with  (one  part,  Loioig)  oil  of  vitriol  diluted  with  half  its  weight  of  water; 
and  the  distillate  collected  in  a  receiver  containing  sufficient  water  to  cover 
the  end  of  the  retort.  Lastly,  the  bromine  is  separated  from  the  supernatant 
watery  Ijqnid  and  rendered  anhydrous  by  distillation  with  chloride  of  cal- 
cium.    When  the  liquid  used  in  the  preparation  of  the  bromine  likewise 

*  The  bromine  of  commerce  frequently  contains  bromide  of  carbon,  probably 
formed  by  tbe  action  of  the  bromine  on  the  ether  naed  in  its  preparation.  The  quantity 
of  this  impurity  yaries  in  different  samples:  one  sample  from  the  Schonebeck  foctory 
contained  between  6  and  8  per  cent.  The  last  portions  of  bromine  thus  contaminated 
require  a  higher  temperature  for  distillation  than  pure  bromine,  the  boiling  point  rising 
from  50*  to  120^  C.  (Posselger,  Agin.  Pkarm.  64, 287.)    [W.] 

VOL.  n.  T 


274  BROMINB. 

contaioi  an  iodide,  the  iodine  mnst  first  be  precipitated  in  the  Cona  of 
iodide  of  copper,  bj  the  addition  of  a  copper-e^lt.  (Balard.) 

2.  The  chlorine  which  serves  to  separate  the  bromine  is  evolved  ia  the 
mother-liquor  itself,  after  that  liquid  has  been  freed  as  completely  as  pos- 
sible by  crystallization  and  other  means,  from  the  peater  wt  of  the  alto 
which  it  contains.  For  this  purpose  the  mother-liauor  is  heated  in  »  dis- 
tillatory i4>paratus,  with  peroxide  of  manganese  and  hydrochloric  acid,  ov 
when  it  contains  a  sufficient  quantity  of  chlorides — ^with  peroxide  of  Biao- 
ganese  and  sulphuric  acid.  The  bromine  which  distils  over  is  afterwarda 
further  purified.  This  method,  as  being  the  more  economical  of  the  two,  Is 
best  adapted  to  the  preparation  of  bromine  on  the  large  eeale,  while  th«  fint 
method  is  to  be  preferred  for  the  detection  of  bromine  in  analysis. 

a.  Six  parts  of  the  mother-liquor  of  the  Salins  spring— which  oini- 
tains  bromide  of  maffnesium,  chloride  of  sodium,  chloride  of  magnesias, 
and  sulphate  of  soda — are  boiled  with  milk  of  lime,  containing  one 
part  of  lime;  the  filtrate  repeatedly  evaporated  as  long  as  it  yields  erya- 
tab ;  and  the  mother-liquor  which  finally  remains,  distilled  with  hydno- 
chloric  acid  and  peroxide  of  manganese/ (Desfosses,  J.  Pkarm.  13,  852.) 
The  liquid,  after  being  decomposed  by  lime,  maybe  treated  with  sulphato 
of  soda,  separated  from  the  gypsum  produced,  and  freed  from  the  greater 
part  of  the  common  salt  by  crystallisation. 

b.  240  parts  of  the  mother-liquor  of  the  Schonebeck  spring  are  dis- 
tilled in  a  glass  retort  with  3  parts  of  peroxide  of  manganese  and  4  JMbits 
of  oil  of  vitriol  diluted  with  2  parts  of  water — the  receiver  contauiiiff 
solution  of  potash.  The  liquid  in  the  receiver  is  afterwards  evaporatel 
to  dryness,  and  the  residual  mixture  of  bromate  of  potassa  with  bromide 
and  chloride  of  potassium,  distilled  with  peroxide  of  manganese  and  sul- 
phuric acid ;  whereupon,  the  bromine  is  evolved.  Or  better :  in  order  first 
to  get  rid  of  the  greater  part  of  the  hydrochloric  acid,  the  mother-liquor  ie 
previously  heated  with  sulphuric  acid  alone,  which  expels  the  hydrocklerie 
acid,  but,  if  carefully  managed  (that  is,  by  not  using  too  large  a  quantity, 
Ldwig),  scarcely  a  trace  of  hydrobromic  acid.  The  sulphates  forsied  am 
then  separated  by  crystallisation,  and  the  remaining  liquid  distilled  with 
oil  of  vitriol  and  peroxide  of  manganese,  (Hermann,  iSekw.  49,  101; 
Fogg.  13,  175;  14,  625.) 

c.  The  mother- liquor  of  the  Kreusnach  salt-spring  is  evaporated  in  an 
iron  vessel  to  one-third  of  its  bulk,  and,  after  standing  for  some  day% 
poured  off  from  the  salts  which  crystalliie  out.  It  is  then  diluted  with 
water— the  lime  precipitated  by  means  of  sulphuric  acid — the  clear  liquid 
separated  from  the  gypsum  b^  straining  and  pressing-— and  Uien  evajwrated 
to  dryness.  The  residue  is  dissolved  in  an  equsl  weight  of  water,  whereby 
a  further  quantity  of  gypsum  is  separated,  and  lastly,  distilled  with  peraxi^ 
of  manganese  and  hydrochloric  acid,  which  may  m  used  in  excess  withont 
giying  rise  to  the  formation  of  chloride  of  bromine.  (Ldwig.)  Mokr 
{Ann.  Pharm.  22,  96)  mixes  4  quarts  of  the  Kreusnach  mother-Uqunr 
with  one  ounce  of  peroxide  of  manganese  and  6  ounces  of  strong  ooai- 
merdal  hydrochloric  acid  in  a  short-necked  flask  connected  with  a 
long  narrow  glass  tube  kept  constantly  cool,  and  heats  the  mixture  till 
the  vapours  rising  in  the  flask  become  colourless.  A  portion  of  the 
hydrochloric  acid  may  pass  over  daring  the  interva^*«o  chlMine  is  formed 
because  the  liouid  is  not  sufficiently  concentrated. 

rf.  After  the  separation  of  iodine  from  the  mother-liquor  of  varec  by 
precipitation  with  chlorine,  according  to  Barruers  process  (p.  249),  the 
remaining  liquid  is  distilled  vitli  pero^pde  of  maa^s^ead  and  oi)  of  yiiriol 


^ 


BROMINB.  275 

(4  parta  of  peroxide  and  3  parts  of  oil  of  yitriol  to  156  parts  of  the 
mother-liqnor)  in  a  glass  retort,  connected,  without  luting,  with  a  tube- 
funnel  and  receiver,  and  lastly  by  means  of  a  bent  tube,  with  a  glass 
cylinder.  The  mixture  is  boiled  till  no  more  red  vapours  appear ;  and 
lastly,  the  whole  of  the  bromine  condensed  in  the  receiver  is  driven  over 
by  a  gentle  heat  into  the  glass  cylinder,  which  is  surrounded  by  ice-cold 
water.  The  residue  is  tested  with  peroxide  of  manganese  and  sulphuric 
acid  to  see  if  it  is  free  from  bromine.  (Barruel,  Bussy,  t/.  Fharm.  23,  19; 
zXsoJ.pr.  Ghem,  13,  251.)  Balard  proceeds  in  the  same  manner,  excepting 
that  he  passes  the  bromine  vapour  into  a  leaden  vessel  filled  with  frag- 
ments ot  iron,  and  prepares  the  bromine  from  the  bromide  of  iron  thereby 
produced.  (Lutrand,  J,  Fharm.  23,  18^.) 

The  bromine  is  generally  contaminated  with  a  small  quantity  of  chlo- 
rine, which  can  only  be  partially  removed  by  washing  with  a  large  quan- 
tity of  water.  (Berzelius.) 

Properties.  Bromine  freezes  at  —19®  (L5wig),  between  —18°  and  —20® 
(SeruUas),  at  —25^  (Liebig),  forming  a  yellowish-brown,  brittle,  crystal- 
line, laminated  mass,  covered  with  bluish-grey  spots.  At  ordinary  tem- 
peratures it  forms  a  very  mobile  liquid  of  specific  ffravity  2*066  (Balard) ; 
between  2*98  and  2  99  at  15®  ^Lowig).  By  reflected  light,  it  appears 
brownish-red  and  nearly  black ;  by  transmitted  light,  transparent  and  of 
a  h^racinth-red  colour  (Balard) ;  m  large  quantities,  it  does  not  transmit 
ordinaj-y  diffused  light ;  but  the  light  of  the  sun  or  of  ^  candle  passes 
through  it  and  exhibits  a  red  colour.  (Ixiwig.)  Does  not  conduct 
electricity.  (Balard,  De  la  Rive  Solly.)  Volatilizes  rapidly  in  the  air, 
and  boils  at  47®  (Balard),  45®  (Lbwig),  being  converted  into  a  yellowish- 
red  vapour,  of  the  same  colour  as  that  of  hyponitric  acid.  It  has  an 
extremely  powerful  and  offensive  odour,  resemoling  that  of  chloric  oxide, 
which  adheres  for  some  days  to  substances  that  have  been  saturated 
with  it.  Vapour  of  bromine  when  inhaled  is  less  injurious  than  chlorine 
ffas,  and  if  mixed  with  a  large  quantity  of  air  may  be  breathed  with  per- 
fect impunity;  nevertheless,  large  quantities  give  rise  to  oppression, 
cough,  giddiness,  bleeding  at  the  nose,  increased  secretion  of  the  mucous 
membrane,  and  lastly,  headache.  These  symptoms  occasionally  continue 
for  six  hours :  they  may  be  alleviated  by  ammonia  and  alcohol,  but  not  by 
sulphuretted  hydrogen.  (Lowig.)  Bromine  has  a  very  sharp,  burning, 
pyBtringent,  and  nauseous  taste.  (Balard;  Lowig.)  One  drop  of  bromine 
administered  to  a  bird  through  the  b^k  is  sujQieient  to  cause  death. 
(Balard.)  A  small  quantity  of  bromine  imparts  a  transient  yellow  colour 
to  the  skin ;  a  larger  quantity  produces  a  yellow,  and  then  a  brown  colour, 
Fhich  can  be  removed  only  with  the  skin  itself,  and  is  attended  with 
violent  itching.  (Balard,  Lowig.)  When  applied  to  the  skin  in  still 
larger  quantities,  it  produces  immediate  corrosion,  and  violent  inflam- 
mation. (L&wig.)  Corrodes  wood,  cork,  and  other  organic  substance?, 
imparting  a  yellow  colour  to  them.  (Balard.)  Like  chlorine,  it  rapidly 
discharges  the  colour  of  tincture  of  litmus  and  indigo  without  fir^t 
reddening  them.  (Balard.)  It  destroys  organic  colours.  (Lowig.)  Colo^r8 
starch  orange-yellow.  A  burning  taper  is  extinguished  in  vapour  of 
bromine,  but  the  flame  previously  appears  red  at  top  and  green  below. 
(Balard.) 

Atomic  Weight:  784  (Berzelius)— 7576  (L»wig)— 75-28» 
— 74-608  to  75-432  (Balard). 

T  2 


2JG  BROMINE. 

Compounds  of  Bromine, 

Bbominb  and  Watsr. 

Htdratb  of  Bromine.  1.  Formed  when  a  mixture  of  a  small  qiuui- 
titj  of  bromine  with  a  large  quantity  of  water  is  cooled  down  to  the 
freezing  point  of  water. — 2.  When  bromine  vapour  is  transmitted,  at  a 
temperatare  of  +  4°  through  a  glass  tube  moistened  with  water.  Obtained 
by  the  first  method,  it  forms  regular  octohedrons,  of  a  hyacinth-red  coloar; 
by  the  second,  a  crystalline  scaly  mass.  When  heated  above  15°,  it  is 
decomposed  into  bromine,  and  a  supernatant  aqueous  solution  of  bromine ; 
at  O'^,  the  two  liquids  again  unite  and  reproduce  the  hydrate.  (Lowig.) 

Calcnlatioii.  Low%. 

Br 78-4  46-56  45-5 

lOHO  900  53-44  54*5 

BriOHO 168-4  '. 10000  lOO'O 

B.  Aqueous  Solution  op  Bromine.  Bromine  Water, — ^One  part  of 
bromine  dissolves  at  15®  in  33*3  parts  water.  The  yellowish-red  solution 
smells  like  bromine,  has  a  very  rough  but  not  acid  taste,  and  remains 
unchanged  even  below  —20®.  It  loses  bromine  when  exposed  to  the  air, 
and  still  more  rapidly  when  heated,  but  does  not  become  acid;  but  when 
kept  for  any  length  of  time,  especiallv  if  exposed  to  the  sun^  it  acquires 
acid  characters,  from  formation  of  hydrobromic  acid.  (Lowig.) 

Bromine  and  Oxtoen. 

Bromine,  like  iodine  and  chlorine,  cannot  be  made  to  unite  directly 
with  oxygen. 

A.     Hypobromous  Acid.     BrO? 

The  similarity  of  bromine  to  chlorine  in  its  behaviour  towards  sali- 
fiable bases  renders  it  highly  probable  that  it  forms  a  hypobromous  acid 
BrO, — analogous  to  hypochlorous  acid,  CIO — which,  in  union  with  salifi* 
able  bases,  forms  compounds  characterized  by  their  bleaching  action  on 
organic  colours.  Such  bleaching  liquids  are  formed  when  bromine  is  added 
to  the  solution  of  a  fixed  alkali  in  excess,  the  alkali  being  either  caustic  or 
combined  with  carbonic  or  some  other  weak  acid.  Under  these  circum- 
stances little  or  no  bromate  is  formed,  and  the  solution  may  be  supposed 
to  contain  a  metallic  bromide  and  an  alkaline  hypobromite  together  with 
free  alkali. 

2KO  +  2Br  =  KBr  +  KO,  BrO. 

These  solutions  do  not  smell  of  bromine,  but  have  an  odour  similar  to 
that  of  the  bleaching  liquids  of  chlorine:  they  decolorize  litmus  and 
indigo ;  disengage  nitrogen  from  ammonia,  and  evolve  bromine  with  all 
acids,  even  with  carbonic  acid. 

KBr  +KO,BrO  +  aSO^*  =  2(KO,S03)  +  2Br. 
When  heated  or  mixed  with  an  excess  of  bromine,  they  lose  their  bleach- 
ing properties,  because  the  hypobromite  is  thereby  resolved  into  metallic 
bromide  and  bromate. 

3(KO,BrO)  »  2KBr  +  KOBrO*. 


BROMIC  ACID.  277 

In  the  ease  of  lime  onlj^  an  excess  of  bromine  does  not  alter  the  bleach- 
ing compound.  With  protoxide  of  mercury  bromine  water  produces  a 
sparingly  soluble  compound  of  bromide  ana  oxide  of  mercnrj,  together 
with  a  liquid  containing  hypobromite  of  mercury  or  free  hypobromous 
acid,  and  yielding  the  latter  by  distillation  in  yacuo.  (Balard.)  Accord- 
ing to  6ay-Lussac  (Compt  Reiid,  14,  931),  hypobromous  acid  may  be 
prepared  in  the  gaseous  form,  by  means  ojf  protoxide  of  mercury  in  the 
same  manner  as  hypochlorous  acid.  ( Vid,  also  Fritzsche,  J.  pr.  Chein, 
24,  291.) 

B.    Bromic  Acid.    BrO". 

Bromsaure,  Acide  Bromiqiie, — Formation.  1.  Bromine- water  with 
hypochlorous  acid  forms  bromic  acid  and  free  chlorine. — 2.  With  oxide  of 
gold,  it  yields  bromate  and  bromide  of  gold.  When  mixed  in  excess  with 
solutions  of  the  fixed  alkalis,  it  forms,  in  the  same  manner  as  iodine  and 
chlorine,  5  atoms  of  metallic  bromide  (or  alkaline  hydrobromate)  and  one 
atom  of  alkaline  bromate. — 3.  Pentachloride  of  bromine  is  resolyed  by 
contact  with  alkalis  into  metallic  chloride  (or  hydrochlorate)  and  a  salt  of 
bromic  acid.  (Balard. ) 

Bromine  is  not  oxidized  by  chloric  oxide,  chloric  acid,  or  concentrated 
nitric  acid.  (Balard,  Connell,  iV.  Bd.  Fhii.  J.  13,  283.) 

Not  yet  known  in  the  free  state. 

Calcalation.  Balard. 

Br     78-4  66-21  64*69 

50     400  33-79  35-31 

BrO* II8-4  100-00  100-00 

(Br'O^  =  2  .  489*17  +  5  .  100  =  1478-3.  BeneUus.) 

Combinations,     a.     Aqueous  Bromic  Acid. 

Preparation.  1.  An  aqueous  solution  of  bromate  of  baryta  is  preci- 
pitated by  an  equiyalent  quantity  of  sulphuric  acid,  and  the  filtrate  gently 
eyaporated  to  a  smaJl  bulk.  (Balard.)  Rammelsberg  digests  100  parts  of 
bromate  of  baryta  with  240  parts  of  water,  and  24  parts  of  oil  of  yitriol, 
for  a  long  time,  frequently  agitating  the  liquid,  and  applying  only  a  yery 
ffentle  heat,  because  a  more  eleyated  temperature  partially  decomposes  the 
bromic  acid.  A  small  quantity  of  bromate  of  baryta  in  variably  remains 
nndecomposed ;  whence  it  is  necessary  to  precipitate  the  sulphuric  acid 
still  remaining  in  the  solution  by  a  quantity  of  baryta  water  just  sufficient 
for  the  purpose,  and  afterwards  to  decant  the  liqnid,  as  filtering-paper 
would  colour  it  yellow.  In  order  not  to  lose  the  bromate  of  baryta  which 
remains  undecomposed,  it  is  digested  with  a  fresh  quantity  of  dilute  sul- 
phuric acid;  the  decanted  liquid  saturated  with  carbonate  of  lime,  and 
concentrated  by  evaporation ;  and  the  bromate  of  lime  contained  in  the 
decanted  solution  converted  into  bromate  of  potash  by  precipitation  with 
carbonate  of  potash. — 2.  Boiling  water  is  saturated  with  bromate  of 
potassa,  and  an  excess  of  hydrofluosilicic  acid  added;  the  mixture  is  then 
heated  for  a  short  time — ^filtered — and  bromate  of  potash  added  to  the 
filtrate  as  long  as  the  salt  continues  to  be  converted  into  a  gelatinous 
mass ;  the  excess  of  bromate  of  potash  is  then  thrown  down  by  alcohol, 
and  the  filtrate  left  to  evaporate  at  a  gentle  heat.  (Lowig.)  Alcohol 
cannot  be  used  in  the  preparation,  inasmuch  as  it  is  violently  aecomposed 
by  contact  with  the  bromic  acid,  and  converted  into  acetic  s^id.  (Serullaa; 


278  BROMINE. 

Rammelebdrg.)  Hence  the  bromate  of  potash  liiuflt  be  mixed  hot  with 
excess  of  hydrofluoailicic  acid,  filtered  on  cooling,  the  solution  gently  eva- 
porated, and  after  a  few  days,  filtered  once  more  through  pounded  glaee. 
(Serullas. )  The  excesisof  hydrofluosilicic  acid  cannot, bo werer, be  completelj 
got  rid  of,  even  by  evaporating  the  solution  with  silica.  (Rammelsber^.) 

Colourless  liquid,  of  a  syrupy  consistence  after  sufficient  concentration  ; 
nearly  inodorous ;  of  a  very  acid  but  not  caustic  taste ;  reddens  litmaa 
dtrongly,  and  bleaches  it  after  a  time.  (BaUrd.)  Of  a  reddish  colours- 
can  not  be  reduced  to  a  syrupy  consistence ;  has  a  peculiar  characteristic 
odour ;  reddens  litmus,  and  then  rapidly  decolorizes  it.  (Serullas.) 

The  acid  volatilizes  both  on  exposure  to  heat  and  in  vacuo,  part 
remaining  undecomposed,  the  rest  being  resolved  into  bromine  vapour 
and  oxygen  gas.  (Balard.)  It  is  decomposed,  even  at  100°  into  vaponr 
of  bromine  and  oxygen,  without  the  evolution  of  any  portion  of  undecom- 
posed acid.  (Rammelsberg.)  Not  decomposed  by  nitric  or  sulphuric 
acid,  excepting  that  the  oil  of  vitriol — in  consequence  of  the  heat  disen- 
gaged— may  evolve  a  small  quantity  of  bromine  vapour  and  oxygen  ga«, 
with  effervescence.  Bromic  acid  and  sulphurous  acid  decompose  each 
other,  yielding  bromine  and  sulphuric  acid:  with  h^drosulphuric  acid 
the  products  are — water,  bromine,  and  sulphur;  with  hydriodic  acid, 
water  and  bromide  of  iodine;  with  hydrobromic  acid,  water  and  bromine; 
with  hydrochloric  acid,  water  and  chloride  of  bromine.  The  salts  of 
these  acids  behave  in  a  similar  manner.  (Balard.)  Alcohol  and  ether 
rapidly  decompose  bromic  acid,  with  rise  of  temperature  and  forma- 
tion ot  acetic  acid.  (Serullas.)  Aqueous  bromic  acid  added  to  concen- 
trated solutions  of  lead  produces  a  white  precipitate,  which  dissolves 
on  the  addition  of  a  larger  quantity  of  water;  it  also  gives  white 
precipitates  with  dilute  solutions  of  mercuroua  and  silver-salts.  (Balard.^ 

b.  The  Saks  of  Bromic  acid,  Bromates,  are  obtained:  1.  By  directly 
combining  the  salifiable  bases  with  aqueous  bromic  acid. — 2.  Bromine  is 
added  to  the  aqueous  solution  of  a  fixed  alkali,  as  long  as  its  colour 
disappears,  and  the  more  sparingly  soluble  bromate  is  separated  from 
the  metallic  bromide  (or  alkaline  hydrobromate)  by  crystallization. — 
8.  Chloride  of  bromine  is  dissolved  in  the  aqueous  solution  of  a  fixed  alkali, 
and  the  alkaline  bromate  separated  from  the  metallic  chloride  (or  alkaline 
bydrochlorate)  by  crystallization. — 4.  Bromine  is  placed  in  contact  with 
oxide  of  gold  (p.  277). 

The  bromates,  when  heated  to  redness,  either  evolve  6  atoms  of 
oxygen  and  leave  metallic  bromides  (as  is  the  case  with  the  bromates  of 
potassa,  soda,  mercury,  and  silver);  or  they  give  off  5  atoms  of  oxygen 
and  1  atom  of  bromine  vapour,  leaving  metallic  oxides  (as  with  the  ^ts 
of  magnesia,  alumina,  and  zinc).  They  explode — either  by  heat  or  by 
percussion — with  charcoal,  sulphur,  antimony,  and  other  combustible 
bodies,  the  report  being  as  loud  as  with  the  chlorates.  The  mixture  of  a 
bromate  with  a  combustible  substance  is  sometimes  infiamed  by  oil  of 
Titriol.  (Lbwig.)  When  treated  with  oil  of  vitriol  alone,  they  give  off 
bromine  and  oxygen.  (Lowig.)  They  are  likewise  decomposed  by  dilute 
phosphoric,  sulphuric,  nitric,  oxalic,  and  acetic  acid,  aided  by  very  gentle 
lieal^  oxygen  gas  being  evolved  and  bromine  set  free.  (Balard;  LOwig.) 
Their  aqueous  solutions  are  decomposed  at  ordinary  temperatures — ^with 
separation  of  bromine — ^by  sulphurous  acid,  hydrosulphurio  acid  (sulphur 
in  this  case  being  deposited,  and  sulphuric  acid  formed — ff.  Eose),  and 
hydrobromic  acid.  (Balard.)  Hydrochloric  acid  added  to  a  bromate  forms 
a  metallic  chloride  and  chloride  of  bromine.  (BaJatd.)    ArsetiiottB  acid 


HYDROBROMIC  ACID.  279 

doM  not  decompose  these  salts.  (Simon.)  They  are  for  the  i&ost  pftft 
solcthle  in  trater.  Their  aqueous  solutions  give^  with  mercuroils  saltl^ 
a  jellowish-white  precipitate^  solnhle  in  nitric  acidj  with  iiiter-saltft 
a  white  precipitate,  which  scarcely  blackens  when  exposed  to  light, 
and  is  readily  soluble  in  ammonia,  bnt  not  in  dilute  nitric  acid ;  a  con- 
oentrftted  solution  likewise  gives  a  white  precipitate  with  lead-salts. 
(Balardj  L5wig.) 

Thd  preparation  of  PBrbromio  add,  Br  O^  was  tried  by  RammdUbetg 
ifi  Ttf iotiS  irays^  bat  failed  in  erery  instance. 


Bromine  and  HtdHoosn. 

A.    Htdrobromous  Acid. 

ffydrol>romige  Saure,  Aeide  kydrobromiqite  hronU»  Known  only  ia 
the  state  of  aqueous  solution  and  in  combination  with  a  few  Salifiable 
bases.  An  aqueous  solution  of  hydrobromic  acid  dissolves  bromine, 
forming  a  dark-red  solution,  which  again  evolves  the  bromine  when 
heated  or  exposed  to  the  air.  (Balard.)  The  alkaline  bromides  or  hydH)-' 
bromates  when  dissolved  in  water  take  up  a  quantity  of  bromine  eqaal  to 
that  which  they  already  contain,  and  form  dark-red  solutions  which,  oft 
exposure  to  heat,  give  off  the  excess  of  bromine  in  the  form  of  tapour. 
(Lowig.) 

B.     Htdrobromic  Acid.    HBr. 

Bpdrohrom,  Hydrobromsaure,  Bromwasserstqfsaure,  S[ydr6brom'Ga9^ 
Acide  hydrobromique. 

Formation,  1.  Bromine  does  not  combine  with  hydrogen  gas  at  ordi- 
nary temperatures^  even  when  exposed  to  direct  sunshine ;  but  if  a  rftd- 
hot  iron  wire  is  introduced  into  hydrogen  gas  saturated  with  bromine 
vapour,  hydrobromic  acid  is  formed  round  the  wire,  though  not  through- 
out the  whole  mass.  (Balard.) — 2.  Bromine  by  itself  does  not  decompose 
water,  when  passed,  together  with  aqueous  vapour,  through  a  red-hot  tube. 
(Balard.)  But  if  the  bromine  is  in  excess  and  the  porcelain  tube  heated 
nearly  to  whiteness,  a  tolerably  large  quantity  of  oxygen  gas  and  hydro- 
bromic acid  is  obtained  >  and  if  the  aqueous  vapoar  predominates,  a 
colourless  gas  is  the  result,  which  smells  like  garlic,  burns  with  a 
purplish-red  flame,  and  is  not  absorbed  by  water  or  potash  (?).  (Bourson, 
CompL  Rend,  13,  1154  j  also  Pogg.  55,  88  ;  also  •/.  pr.  Chem.  25,  400.) 
Under  the  direct  influence  of  the  sun's  rays,  bromine  gradually  separates 
oxygen  gas  from  water,  and  forms  hydrobromic  acid!  (Lbwig.)  When 
the  mixture  is  brought  in  contact  with  substances  which  have  an  aflinity 
for  the  oxygen  of  the  water,  such  as  phosphorus,  hypophosphorous  acid, 
sulphurous  acid,  arsenious  acid,  metals,  &c.,  hydrobromic  acid  is  instantly 
produced.  ^Balard.)  Moreover,  on  boiling  bromine  with  fumiug  nitric 
acid,  a  small  quantity  of  hydrobromic  acid  is  evolved,  in  consequence  of 
the  hyponitric  acid  oeing  converted  by  the  oxygen  of  the  water  into 
nitric  acid.  (Connell,  N.  Ed.  Phil.  J.  1 3,  283.)— 3.  Bromine  separates 
hydrogen  from  most  other  hydrogen  compounds,  namely,  from  phosphn- 
retted  hydrogen  gas,  gaseous  or  aqueous  hydrosulphuric  and  hydriodic 


280  BROMINE. 

acidfl,  and  aqueous  ammonia.  It  is  also  very  rapidly  conrerted  into 
hydrobromic  acids  by  Yolatile  oils  and  resins,  by  alcohol  and  ether  in 
the  course  of  a  few  days,  and  by  fixed  oils  and  vinegar  after  a  longer 
interval.  (Balard.) 

Preparation.  1.  Bromine  is  made  to  combine  with  phosphorus,  and 
the  compound  heated  in  a  retort  with  a  very  small  quantity  of  water. 
(Balard.) — 2.  Millon  (•/.  Pharm.  28,  299)  heats  a  mixture  of  one  part 
of  phosphorus,  12*5  parts  of  bromine  and  7*8  parts  of  bromide  of  potas- 
sium with  a  small  quantity  of  water.  [For  the  method  of  proceeding  and 
the  calculation,  vid,  p.  262,  under  the  head  of  Hydriodic  acid.'] — 3.  Bro- 
mide of  potassium  is  heated  with  three-fourths  of  its  weight  (Lowig)  of  oil 
of  vitriol.  In  this  process  the  gas  is  very  apt  to  be  contaminated  with 
vapour  of  bromine,  (which  may  be  separated  by  agitation  with  mercury), 
and  with  sulphurous  acid  ;  the  quantity  of  these  impurities  is,  however, 
less  in  proportion  as  the  crystals  of  bromide  of  potassium  are  larger,  and 
the  excess  of  oil  of  vitriol  employed  is  smaller.  (Balard.)  The  gas  is 
received  over  mercury. 

Properties,  Colourless  gas,  having  a  very  pungent  odour,  which 
excites  coughing,  and  a  strongly  acid  taste ;  reddens  litmus  strongly, 
and  excites  itching  and  inflammation  when  applied  to  the  skin.  Fumes 
in  the  air  more  strongly  than  hydrochloric  acid.  (Balard.)  Specific  g^ra- 
vity  (I,  279);  according  to  Lowig,  it  is  2*71. — Liquefies  at  —  92^  F.; 
soLdifiesat— 100°F. 

Calculation.  Vol.  Sp.  gr. 

Br 78-4  98*74  Bromine  vapour i  2-71775 

H  1-0  1-26  Hydrogen  g«»      i  003465 

HBr 79-4  100*00  Hydrobromic  add  ^as....  1  2*75240 

HBr  »  6*24  +  484*15  »  495*39.    (Benelius.) 

Decompotitioru,  Hydrobromic  acid  gas  is  not  decomposed  when  trans- 
mitted, either  alone  or  mixed  with  oxygen  ^,  througli  a  red-hot  glass 
tube ;  or  when  a  burning  taper  is  introduced  into  the  mixture.  1.  Oil  of 
vitriol  and  aoueous  hjrdrobromic  acid  react  on  each  other  but  slightly, 
yielding  small  quantities  of  sulphurous  acid,  water,  and  bromine ;  with 
nitric  acid,  the  decomposition  is  slow  at  first,  but  afterwards  becomes 
more  rapid — especially  if  heat  is  applied  to  the  mixture  :  the  products 
are  hyponitric  acid,  water,  and  bromine  (a  case  of  reciprocal  affinity, 
vide  p.  279, 2).  Bremic  acid  and  hydrobromic  acid  act  upon  each  other  m 
such  a  manner  as  to  form  water  and  bromine. — 2.  Chlorine  mixed  with 
hydrobromic  acid  gas  forms  hydrochloric  acid,  and  separates  the  bromine 
in  red  vapours,  which  condense  in  drops;  if  the  chlorine  is  in  excess,  chlo- 
ride of  bromine  is  produced. — 3.  Potassium  separates  the  bromine  from 
hydrobromic  acid  gas  at  ordinary  temperatures;  tin,  with  the  aid  of  gentle 
heat,  leaving  half  a  measure  of  nydrogen.  Mercury  has  no  eflect  on  the 
gas. — 4.  The  oxides  of  lead  and  silver  decompose  the  gas  at  ordinary 
temperatures  into  metallic  bromide  and  water  ;  most  of  the  other  salifi- 
able metallic  oxides  efiect  this  change  when  heated. — 5.  Metallic  acids 
and  peroxides,  such  as  antimonic  acid,  peroxide  of  manganese,  and  the 
xcd  and  brown  peroxides  of  lead,  undergo  mutual  decomposition  with 
aqueous  hydrobromic  acid,  yielding  bromide  of  the  metal  (or  hydrobro- 
mate  of  the  oxide)  and  free  bromine.  (Balard.) 


BROMINE  AND  PHOSPHORUS.  281 

i:  Combinations, — a.  Aqueous  Hydrobromic  add,  Solution  of  hydrohro- 

kr  mid  acid, — 1.  Hydrobromic  acid  ^;as  is  rapidly  and  copiously  absorbed  by 

i.  water,  with  disengagement  of  heat  (Balard)  ;  and  by  ice,  which  is  there- 

by liquefied.  (Lowig.) — 2.  Bromine  is  added  to  phosphorus  immersed  in 
water,  in  small  quantities  at  a  time,  to  avoid  too  violent  a  disengage- 
ment of  heat.     The  addition  of  the  bromine  is  continued  till  the  whole  of 
r.  the  phosphorus  has  disappeared  ;  after  which,  the  aqueous  hydrobromic 

acid  is  obtained  pure  by  distillation.  (Lowig.)— 3.  Bromide  of  antimony 
c  is  decomposed  by  a  sufficient  quantity  of  water  to  prevent  any  antimonic 

oxide  from  being  dissolved.  (Serullas.)  Antimony  always  remains  in  the 
solution.  (Lowig.) — 4.  Sulphuretted  hydrogen  gas  is  passed  through 
water  containing  a  little  bromine — small  quantities  of  that  substance 
repeatedly  added  to  the  liquid  as  often  as  the  hydrosulphurio  acid  is  in 
excess — and  the  solution  filtered  from  the  precipitated  sulphur.  (Balard.) 
In  this  process,  bromide  of  sulphur  is  formed,  which  volatilizes  in  dense 
fumes  and  is  decomposed  by  water  into  hydrobromic  acid  and  sulphurous 
acid.  (Lowig.) — 5.  One  part  of  bromide  of  potassium  is  distilled  with 
f  pt.  of  oil  of  vitriol  and  12  pts.  of  water,  and  the  distillate  freed  from 
excess  of  bromine  by  exposure  to  the  air.  (Lowig.) — 6.  Bromide  of 
barium  dissolved  in  water  is  decomposed  by  an  equivalent  quantity  of 
dilute  sulphuric  acid,  and  the  solution  filtered,  ((Hover,  PhiL  Mag,  J, 
19,  92.) 

Aqueous  hydrobromic  acid  is  colourless ;  in  the  most  concentrated 
form  it  has  a  specific  gravity  of  1*29  (Lowig),  and  fumes  in  the  air;  has 
a  strongly  acid  taste.  (Balard.)  The  strongest  acid  boils  at  a  temperature 
below  100°,  and  is  thereby  rendered  weaker,  owing  to  the  loss  of  hydro- 
bromic acid  gas  ;  a  more  ailute  acid  boils  at  a  temperature  above  100", 
and  a  very  dilute  acid  becomes  stronger  on  boiling.  (Lowig.)  The  aqueous 
acid  undergoes  the  same  decompositions  as  hydrobromic  acid  gas,  as 
described  under  the  numbers  1,  2,  4,  and  5.  When  mixed  with  nitric 
acid,  it  dissolves  gold  and  platinum.  (Balard.) 
b.     Hydrobromates,     Vide  Bromides, 

a    Bromine  and  Boron. 
Bromo-boracic  Acid. 

When  vapour  of  bromine  is  passed  over  an  ignited  mixture  of  vitrefied 
boracic  acid  and  charcoal,  a  colourless  ffas  is  obtained,  which  has  a  very 
penetrating  odour  and  extremely  acid  taste,  reddens  litmus  strongly, 
and  forms  white  fumes  in  contact  with  moist  air.     It  appears  to  be  com- 

Sosed  of  BBr*.  It  is  rapidly  absorbed  by  water,  but  is,  at  the  same  time, 
ecomposed,  with  separation  of  boracic  acid.  When  brought  in  contact 
with  dry  ammoniacal  gas,  it  forms  a  white,  volatile,  pulverulent  salt, 
which  has  a  pungent  taste,  and  is  resolved  by  contact  with  water  into 
bromine  and  borate  of  ammonia.  (Poggiale,  Compt,  Bend,  22, 124.)  IT 

Bromine  and  Phosphorus. 

A.  Bromide  of  Phosphorus.  When  phosphorus  is  brought  in 
contact  with  bromine  contained  in  a  vessel  full  of  carbonic  acid  gas, 
combination  takes  place  instantaneously,  and  with  incandescence,  the 
product  being  sometimes  terbromide,  sometimes  pentabromide  of  phos- 
phorus. (Balard.)  Small  fragments  of  phosphorus  thrown  into  bromine 
take  fire  and  produce  dangerous  explosions.  (H.  Rose,  Fogg,  27,  128.) 


889  BSOMIKB. 

a.  IMrwnidet^PhMpkarui.  Protchrtmure  de  Pho»phore.  1.  Phos- 
phorofl  is  fldded  io  piedea,  not  weighing  more  than  a  quarter  of  a  grain, 
to  perfectlj  anhjdroai  bromine,  till  the  liquid  beeomes  ooloorlees,  after 
which  the  compound  is  separated  by  distillation  from  the  exeeas  of  pho6- 
phoms.  f  Ldwig.)  In  order  to  atoid  the  chance  of  explosion,  it  is  Vert 
to  ponr  the  bromine  into  a  wide-monthed  bottle,  and  introduce  perfectlj 
dry  phoNsphorus  in  a  glass  tube,  sealed  at  bottom,  and  placed  upright  in 
the  liquid;  so  that  on  dosing  Uie  bottle,  the  bromine  rapout  maj  dowlj 
come  in  eontaet  with  the  phosphotus.  (H.  Rose,  Po^*  28,  550.)— 
3.  Vapour  of  phosphorus  is  passed  over  protobromide  or  dibromide  of  mer- 
cury, which  is  heated  in  a  fflass  tube  bj  means  of  &  spirit-lam{>,  atld  the 
product  collected  in  a  cooled  receirer;  the  neir  compound  is  purified  froin 
excess  of  phosphorus  bj  distillation.  (Ldwig.) 

Colourless,  transparent,  mobile  liquid,  which  does  not  freeiie  eren  at 
^  12°,  is  Tcrj  Tolatile,  and  emits  dense  white  fumes  in  the  air;  has  the 
pungent  odour  of  hydrobromie  acid ;  it  probably  reddens  litmus  paper 
only  when  moisture  is  present  (Lawig;  Balard.) 

CalcaUtioxi.  Lowig.  Volume. 

P  31*4  ll'78  11'7         Vapour  of  pbosphonxs    ....  1 

SBr   ....  235*2  88*22  88'8         Vapour  of  bromine 6 

PBr»  ....  266*6  100*00  100*0 

DecompoHtions.  1.  By  water,  with  great  disengagement  of  heaL 
intb  j^hosphorous  acid  and  hydrobromie  acid,  which  latter,  when  a  small 

?aantitT  only  of  water  Is  employed,  is  evolved  in  the  gaseous  form. 
Balard.)  At  +  8",  the  decomposition  takes  place  but  slowly,  even 
when  the  mixture  is  repeatedly  snaken ;  at  25°  it  proceeds  irery  rapidly. 
(Lttwig.)  2.  By  chlorine^  into  chloride  of  phosphorus  and  free  bromine. 
(Balard.) 

Terbroniide  of  phosphorus  is  capable  of  dissolving  an  additional 
quantity  of  phosphorus,  whereby  it  acquires  the  property  of  setting  fire 
to  combustible  bodies  brought  in  contact  with  it  in  the  open  air  (Balard), 
of  forming  a  pellicle  of  phosphorus  when  exposed  to  air,  and  depositing 
phosphorus  when  decomposed  with  water.  (L5wig.) 

b.  Pentabramide  of  Pkotphorut,  Perbfomure  de  PJuaphore, — 
1.  Sublimes  on  bringing  bromine  in  contact  with  phosphorus,  not  in  very 
great  excess.  (Balard.) — 2.  Formed  by  mixing  terbromide  of  phosphorus 
with  bromine.  (Lb wig.) — 8.  Bromine  decomposes  iodide  of  phosphorus. 
(Balard.) 

Lemod-yellow  solid,  which  crvstallizes  in  the  rhombohedral  form  after 
fusion,  in  needles  when  sublimed.  Melts  at  a  moderate  heat  to  a  red 
liquid,  which  at  a  higher  temperature  evoltes  red  vapours;  evolves  dense 
pungent  fumes  in  the  air.  (Balard.) 

Calculation.  Lowig.  Volume. 

P 31*4  7*42  6*8        Vapour  of  phosphorus  ....  1 

5Br    392*0  92*58  93*2        Vapour  of  bromine  10 

PBr»    423*4  100*00  1000 

Decompositions.  1.  By  chlorine,  into  chloride  of  phosphorus  and  free 
bromine. — 2.  By  heated  metals  into  metallic  bromide  and  phosphide. 
(Balard.)— 3.  By  oxide  of  copper  and  red  oxide  of  mercury  into  metallie 
biromide  and  phosphate  of  the  oxide.  (L5wig.) — 4.  By  water,  with 
rise  of  temperature,  into  phosphoric  and  hydrobromie  altidB,  (Balard.) 


BROMIKB  AKD  ilULPHUR.  383 


B.  ItTDROBROiri.Tis  OF  PfiospfixTRSTTBD  HtDROGSK.  L  Formed  when 
dry  phosphiir^ttcd  hjdrbgen  abd  hjdrobrothie  acid  gases  are  brought  in 
contact  with  each  other. — 2.  Bromide  of  silicinm  is  introduced  under 
a  bell-jar  full  of  phosphuretted  hydrogen  gas,  and  a  small  quantity  of 
water  added,  T^h^reby  the  bromide  of  silicinm  is  conrerted  into  siliea 
and  hydrobrdmie  acid  gas.  I'he  eompottttd  crystallised  on  the  sides  df 
the  vessel.  (SeruUas.) 

Colourless  cubes,  sometimes  transparent,  sometiine^  opaque.  (Serullas.) 
Boiling  point  about  S(f;  specific  grarlty  of  the  ropdut  =±:  1*906.  (Blnten, 
Ann.  Ckim.  Phys.  68,  430.) 

When  exposed  to  the  air  it  absorbs  moisture  j  and  when  treated  with 
water,  it  is  resolred,  with  riolent  ebhllition,  into  aqueous  hydrobromic 
acid  and  non-spontaueously  inflammable  phosphuretted  hydrogen  gas. 
(Serullas.) 

Calcalatton.  Vol.      8p.  gr. 

PH 34*4  30*23  Phosphvi-etted  hydrogen  gas ^  ....  0*5962 

HBr 79-4  69-77  Hydrobromic  acid  gas    |  ....  1-3762 

PH«,HBr  113-8     ....100*00              Hydwbromate of  phosphuretted  hy-K  j.^y^^ 

'  drogen  vapour    ) 


Brominb  and  Sulphur, 

A.  Bromidb  of  ScTLpauR.  Sulphur  dissdtes  in  bromine  without 
any  observable  rise  of  temperature  (H.  Rose),  forming  a  brownish-red 
oily  liquid,  lighter  than  bromine,  darker  than  chloride  of  sulphur.  This 
compound,  when  exposed  to  the  air,  evolyes  white  fumes,  which  smell 
like  chloride  of  sulphur;  it  reddens  dry  litmus-paper  rery  feebly,  but 
ihoistened  litmus-paper  strongly.  It  is  but  vtery  slowly  decomposed  by 
cold  water :  at  a  boiling  heat,  however,  the  decomposition  is  frequently 
attended  with  slight  explosion,  the  products  being  hydrobromic,  hydro- 
sulphuric,  and  sulphurous  acidd.  Cnlorine  converts  it  into  chloride  of 
dulphur  aiid  free  bromibe.  (Balatd.) 

At  ordinary  temperatures,  75  partd  (one  atom)  of  bromine  dissolve 
d2  parts  (2  atoms)  of  sulphur;  and  when  aided  by  heat,  a  larger  quantity^ 
which,  however,  separates  again  on  cooling.  The  solution  is  decomposed  by 
water,  and  more  rapidly  when  the  mixture  is  shaken,  into  hydrobromio 
acid,  sulphur,  and  sulphurous  acid.  When  it  is  distilled  with  phosphorus, 
bromide  of  phosphorus  passes  over,  and  sulphur  is  left  in  the  retort. 
When  it  is  distilled  alone,  half  the  sulpbur  remains  behind,  and  the  distillate 
consists  of  monobromide  of  sulphur.  This  compound  is  red,  heavier  than 
water,  very  vohitile,  and,  on  exposure  to  the  air,  emits  the  same  vapour 
as  the  dibromide  of  sulphur,  with  a  similar  odour ;  it  has  a  sharp,  acid, 
burning  taste,  and  does  not  redden  dry  litmus-paper.  It  is  decomposed 
b^  water  in  a  similar  manner  to  the  dibromide.  Nitric  acid  attacks  it 
violently,  converting  it  into  hydrobromic  acid  and  sulphuric  acid.  With 
ammonia,  it  yields  sulphur,  nitrogen  gas,  and  hydtobromate  of  ammonia. 
When  passed  in  the  fbrm  of  vapour  over  ignited  iron,  it  produces  bromide 
and  sulphide  of  iron,  with  disengagement  of  light  and  heat.  (Lowig.) 

Bromine  does  not  appear  to  form  definite  compounds  with  sulphur. 
If  a  saturated  solution  of  sulphur  in  bromine,  prepared  at  ordinary  tem- 
peratures, is  partially  distilled  at  a  very  gentle  heat,  the  distillate,  which 


284  BROMINE. 

is  of  as  deep  a  red  colour  as  bromiue,  has  the  oomposition  h;  the  residue 
again  distilled  at  a  somewhat  higher  temperatare,  but  still  far  belo'vr  its 
boiling  point,  yields  the  distillate  c;  and  sulphur,  rendered  darker  by  the 

Sresence  of  bromine^  remains  in  the  retort.  On  distilling  this  residue,  a 
irty  brown  liquid  a,  is  obtained.  Again,  if  the  distillate  c  is  exposed  to 
a  gentle  but  gradually  increasing  heat, — the  temperature  however  beiog- 
always  kept  below  the  boiling  point  and  the  receivers  thrice  changed 
during  the  process, — ^the  distillate/  passes  over  first  and  then  the  dis- 
tillate e,  both  resembling  bromine  in  colour, — ^and  lastly  the  distillate  g^ 
which  is  somewhat  yellower;  the  residue  in  the  retort  consists  of  dirty 
brown  sulphur  containing  bromine.  (H.  Rose.) 

«,  *,  c,  rf,  «,  /. 

8 89-57  7801  7442  27'59  1502  938 

Br. 10-43  21-99  25-58  72*41  84-98  90-62 

SBp 100-00  100-00  10000  100-00  100-00  10000 

B.  Sidphate  of  Bromide  of  svlphur  f  A  solution  of  sulphur  in  bro- 
mine— in  which  the  quantity  of  sulphur  present  is  not  sufficient  to  render 
it  less  fluid  than  bromine  itself, — absorbs  the  vapour  of  anhydrous  sul- 
phuric acid  in  abundance,  without  undergoing  any  change  of  appearance. 
On  distilling  the  mixture,  no  sulphurous  acid  is  evolved,  but  sulphur  is 
left  behind.  The  distillate  first  obtained  is  reddish-brown,  fuming,  and 
readily  soluble  in  water.  The  aqueous  solution,  which  is  coloured  yellow 
by  free  bromine,  likewise  contains  hydrobromic  and  sulphuric  acids.  The 
distillate  obtained  at  a  subsequent  period  is  reddish-brown,  and  dissolres 
very  slowly  in  water,  with  separation  of  sulphur.  The  solution  contains 
hydrobromic  and  sulphuric  acids,  but  no  free  bromine.   (H.  Rose,  Fo^^g. 

44,  1,  327.)  I 

C.  Sulphate  of  Hydrobromic  acid?  Anhydrous  sulphuric  acid  I 
absorbs  hydrobromic  acid  gas  and  deliquesces  to  a  red  liquid.  (Aim6,  t/l  ' 
Pharm.  21,  88.) 

D.  Bromide  of  sulphide  of  Carbon.  Bromine  dissolves  with 
great  readiness  in  bisulphide  of  carbon,  by  which  it  is  separated  from 
solution  in  water.  (Lampadius,  Schw,  50, 378. )  The  red  solution  is  heavier 
than  water,  has  a  peculiar  odour,  both  of  bromine  and  of  bisulphide  of 
carbon,  and  moreover  very  pungent ;  it  gives  up  its  bromine  to  aqueous  i 
solutions  of  the  alkalis,  but  not  to  pure  water.  (Lowig.)  Does  not  con- 
duct electricity.  ( Solly.) 

Bromine  and  Selenium. 

Bromide  of  Selenium.  The  two  elements  are  miscible  in  various 
proportions;  but  the  compound  containing  5  parts  of  bromine  and  one 
part  of  selenium  appears  to  be  the  most  stable.  Bromine  rapidly  com- 
bines with  powdered  selenium,  the  combination  being  attended  with  a 
hissing  noise  and  strong  disengagement  of  heat ;  the  mixture  instantly 
solidifies  to  a  brownish-red  mass,  interspersed  with  portions  of  a  yellow  I 

colour.  When  exposed  to  the  air,  it  emits  fumes  which  have  exactly  the 
odour  of  chloride  of  sulphur.  The  compound  volatilizes  when  heated, 
part  being  decomposed  into  bromine  and  selenium,  and  the  rest  sublimed, 
without  decomposition,  in  the  form  of  a  yellow  mass.  It  dissolves  com- 
pletely in  water,  with  the  exception  of  a  few  flakes  of  selenium.     The 


METALLIC  BROMIDES.  285 

colourless  solution  contains  hydrobromic  and  selenious  acids,  and  on  the 
addition  of  hydrochloric  acid  gires  a  precipitate  of  selenium  [which 
appears  difficult  of  explanation].  (Serallas.) 

Bbominb  and  Iodine. 

A.  Sub-bromide  of  Iodine.  Formed  when  iodine  is  brought  in 
contact  with  a  small  quantity  of  bromine.  Solid;  volatilizing  in  reddish- 
brown  vapours,  which  condense  to  reddish-brown  crystals,  collected  toge- 
ther in  fern-like  masses.  (Balard.) 

B.  Pentabbomide  of  Iodine.  Iodine  forms  with  excess  of  bromine 
a  dark-brown  liquid  (Balard),  having  an  offensive  odour  and  astringent 
taste.  (L&wig.)  It  dissolves  pretty  freely  in  water,  with  separation  of 
iodine  or  bromine,  according  as  either  may  be  in  excess.  (Lowig.)  The 
brownish-red  solution  contains  undecomposed  bromine  of  iodine  ;  hence  it 
decolorizes  litmus  without  previously  reddening  it.  With  alkalis,  it 
yields  a  metallic  bromide  (or  hydrobromate)  and  an  alkaline  iodate. 
(Balard.)  It  is  also  decolorized  by  exposure  to  the  sun's  rays,  in  conse- 
quence of  the  formation  of  hydrobromic  and  iodic  acids.  (Lowig.) 

Hydrated  Pentabromide  of  iodine,  A  mixture  of  bromide  of  iodine 
with  a  small  quantity  of  water  is  exposed  to  a  temperature  below  0°. 
Brownish-yellow  needles,  frequently  united  in  arborescent  masses.  At 
a  temperature  above  +  4°,  it  is  resolved  into  bromide  of  iodine  and 
water,  which  contains  a  small  quantity  of  bromide  of  iodine  dissolved:  on 
exposure  to  cold,  the  two  strata  of  liquid  again  unite  and  reproduce  the 
hydrate.  (Lbwig.) 

Other  Compounds  of  Bromine. 

A.  With  Chlorine. — B.  With  metals,  forming  the  ife/aZZi(;^romi(f«9. 
These  compounds  are  obtained:  1.  When  bromine  is  brought  in  contact 
with  a  metal.  Potassium,  arsenic,  antimony,  and  tin  combine  directly 
with  liquid  bromine,  producing  vivid  combustion;  potassium  even  pro- 
duces explosion.  Bismuth,  iron,  and  mercury  combine  with  bromine  at 
ordinary  temperatures  without  combustion  ;  but  if  heat  be  applied,  com- 
bustion takes  place.  Gold  combines  gradually  with  bromine  at  ordinary 
temperatures;  platinum  does  not.  (Balard;  Lowig.)  With  many  metals, 
the  application  of  heat  is  necessary  to  induce  combination.  (Berthemot.) 
— 2.  Many  metals  abstract  bromine  from  hydrobromic  acid  gas  (p.  288). 
Vapour  of  bromine  passed  over  ignited  potassa,  soda,  baryta,  or  lime, 
forms  a  metallic  bromide,  the  action  being  attended  with  development  of 
light  and  heat  and  evolution  of  oxygen  gas :  from  alkaline  carbonates 
bromine  immediately  expels  the  carbonic  acid ;  oxide  of  silver  is  decom- 
posed by  it,  even  at  ordinary  temperatures.  On  the  other  hand,  it  does 
not  decompose  the  sulphates  of  potassa^  magnesia,  zirconia,  or  oxide  of  zinc, 
even  with  the  aid  of  heat.  (Balard.) — 4.  Metallic  oxides  brought  in  con- 
tact with  hydrobromic  acid  produce  metallic  bromides  and  water,  the 
decomposition  taking  place,  sometimes  at  ordinary,  sometimes  at  higher 
temperatures. 

The  metallic  bromides  are  solid  at  ordinary  temperatures ;  most  of 
them  fuse  at  a  moderate  heat,  and  volatilize  at  higher  temperatures.  They 
closely  resemble  the  chlorides.  But  few  metallic  bromides  (gold,  pla- 
tinum) give  up  their  bromine  by  mere  exposure  to  heat ;  many  of  them, 


386  BBOMIKfl. 

however^  when  i^ited  under  such  pirpnmstMioes  th%i  the  air  hsm  im^ 
aeceM  to  them,  give  off  vapoor  of  bromine,  and  are  converted  into  o^jdei. 
(Berthemot.)  Chlorine,  with  tbe  aid  of  heat,  drives  oat  the  bromine  and 
converts  them  into  chlorides.  Hydrochloric  acid  gas  decomposes  them 
at  a  red  heat,  forming  a  metallic  chloride  aud  hydrobromic  acid  gas, 
equal  in  volume  to  the  hydrochloric  acid.  Anhydrous  boracic  acid  does 
not  decompose  bromide  of  potassium  at  a  red  heat;  but  if  water  has 
access  to  the  mixture,  borate  of  potassa  and  hydrobromic  acid  gae  are 
produped.  Concentrated  sulphuric  or  nitric  acidf  separates  bromine  from 
metallic  bromides,  with  formation  of  sulphurous  acid  or  nitrous  gas, 
sometimes  accompanied  with  hydrobromic  acid.  (Balard.^  When  fused 
with  sulphate  of  potassa,  the  metallic  bromides  evolve  sulphurous  acid  and 
bromine.  When  added  to  a  bead  of  microcosmic  salt  saturated  with 
oxide  qf  copper,  they  impart  a  blue  colour  to  the  blow-pipe  flame,  similar 
to  that  proonced  by  a  chloride  under  the  same  circumstances;  but  the 
colour  inclines  more  to  green.  (Berzelius.)  Pure  metallic  bromides  dis- 
tilled with  chromate  of  potassa  and  oil  of  vitriol,  yield  pure  bromine, 
which  loses  its  colour  when  treated  with  aqueous  ammonia;  but  if  a 
chloride  is  mixed  with  the  bromide,  chromate  of  terchloride  of  chrominm 
likewise  passes  over,  and  forms  a  yellow  liquid  when  mixed  with  the  am- 
monia. (U.  "Roae,  Analyt,  ChemAj  415.)  A  few  metallic  bromides  remain 
unaltered  in  contact  with  water;  viz.  dibromide  of  copper,  dibromide  of 
mercury,  and  bromide  of  silver.  A  few  others  are  converted  into  metallic 
oxides  and  hydrobromic  acid,  which  dissolves  in  the  water;  but  the  de- 
composition generally  takes  place  in  such  a  manner  that  the  metallic 
oxide  retains  a  portion  of  bromide,  and  the  hydrobromic  acid  dissolves  a 
portion  of  the  oxide  produced  (this  is  the  case  with  the  bromides  of  arsenic, 
antimony,  tellurium,  and  bismuth).  Most  metallic  bromides  dissolve  com- 
pletely in  water,  forming  solutions  which  may  be  regarded  as  containing 
either  metallic  bromides  or  hydrobromates  of  metallic  oxides. 

HydraUd  Metallic  BronUde$,  or  ffydrobromatei  of  Metallic  Oxides, 
Hydrobromates,  Bromhydrates. — Preparation,  1.  By  dissolving  a  me- 
tallic bromide  in  water,  or  bringing  bromine  and  a  metal  in  contact  with 
water.  2.  By  the  direct  combination  of  a  base  with  ao  neons  hydrobromic 
acid.  8.  By  dissolving  certain  metals  in  aqueous  hyarobromic  acid,  the 
action  being  attended  with  evdution  of  hydrogen  gas,  proceeding  either 
from  the  acid  or  from  the  water :  thus 

Zn  +  HBr  =  ZnBr  +  H 
or:  Zn  +  HBr  +  HO  =  ZnO.Br  +  H. 

The  aqueous  solutions  of  the  bromides  of  calcium,  magnesium,  manganese, 
and  zinc  exert  an  alkaline  reaction.  (Bonsdorff.)  Hydrobromates  are 
often  resolved  by  evaporation  to  drj^ness  and  subsequent  exposure  to  a 
higher  temperature, — sometimes  even  by  crystallization — into  metallic 
bromides  and  water;  but  some  of  them,  as  those  of  the  earths,  evolve 
hydrobromic  acid  together  with  the  aqyeous  vaponr,  which  escapes,  anj 
leave  metallic  oxides.  Chlorine  addea  to  an  aqueous  solution  of  one  oi 
these  salts  sets  bromine  free  and  forms  a  chloride  or  hydrochlorat^ : 

KBr  +01  »  KCl  +  Bri  or,  KG,  H Br  +  Q  »  KO, HCl  f  B^. 

Hence  chlorine  water  or  chlorine  gas  colours  the  solutions  yellow  or  yei- 
lowish-red  (without  destroying  the  colour  if  added  in  excess);  and  on 
subsequently  agitating  the  li<^uid  wit^  ether,  a  reddish-yellow  solution  of 
bromine  in  ether  is  obtained,  which  floats  pn  the  su^ace  of  the  nearly  de- 
colorized watery  liquid;  the  liberated  bromine  also  communicates   an 


METAI.LIC  BROMIDES.  SSf 


ii 


orange-yellow  colour  to  solid  or  gelatinous  starch.     One  part  of  bromide 
a  of  potassium  dissolved  in  1000  parts  of  water  communicates  in  this  man- 

it  ner  an  orange  tint  to  ether  or  gelatinous  starch ;  ^  pt.  colours   ether 

2  very  feebly,  and  starch  pale  orange ;  ^  pt.  no  longer  colours  ether,  and 

gives  merely  a  pale  yellowish  tint  to  gelatinous  starch.  If  the  bromide 
of  potassium  is  mixea  with  iodide,  the  yellow  colour  caused  by  the  bromine 
is  completely  masked  by  the  bine  produced  hj  the  iodme.  (Brandos, 
Schw.  58,  482.^  An  aqueous  solution  of  a  bromide  mixed  with  sulphate 
h  of  copper  proauces  a  black  spot  on  polished  silver.  (Berzelius.)     Salts  of 

;  hypochlorous  acid — chloride  of  lime,  for  example— also  liberate  bromine 

I  from  these  solutions ;  so  likewise  do  oil  of  vitriol,  chloric  a^id,  an4  nitric 

;  acid.  (Balard.)     Dilute  sulphuric  acid  generally  separates  undeoomposed 

bydrobromiff  a«id,  which  ma^  be  obtained  by  fustillation.  ^Lowig.)    The 
f  salts  of  hydrobromie  acid  give  a  white  pracipitate  with  lead-iAlts,  and 

,  yellowish-white  with  mercurous  and  silvei^salts.      The  precipitate  of 

;  bromide  of  lead  does  not  dissolve  on  thp  addition  of  a  large  quantity  of 

water  (this  distinguishes  it  from  the  chloride),  and  the  precipitate  of  bro? 
mide  of  silver  is  insolnble  in  dilute  nitric  acyl :  it  la  also  insoluble  in 
ammonia,  unless  the  amiponia  be  strong.  (L5ing.)  A  solution  of  bromide 
of  potassium  containing  one  par^  of  bromine  in  85,000  of  water  ffives  a 
cloud  and  precipitate  with  nitrate  of  mercurous  oxide;  irith&iUate  of  silver 
only  a  very  slight  cloud;  with  100,000  parts  of  vrater^tfae  mereurous  salt 
still  gives  a  perceptible  tuibidity,— 4fae  ailyer-salt,  a  scarcely  visible  <doud 
after  some  time;  with  200,000  parts  of  valer  the  mercurous  salt  gives, 
after  a  while,  a  slight  opalescence,  but  the  silver-salt  has  no  effect  (Las- 
saigne,  /.  Chim.  Med.  6,  520.) 

Metallic  bromides  sometimes  combine  with  the  oxides  of  the  cor- 
responding metals,  forming  compounds  called  Oxtf-hrmnidei.  These  eom- 
pounds,  however,  still  retain  water,  even  after  drying  at  high  tempera- 
tures, and  may  be  regarded  either  as  compoiuids  of  hydnUed  metallie 
bromides  with  metallic  oxides,  or  of  hydrobromates  of  metallic  oxides 
with  excess  of  oxide  (arsenie,  antimony,  bismuth). 

Many  metallic  bromides  combine  with  ammonia  in  definite  propor- 


Eleetro-negative  metallic  bromides  oombane  with  electro-positiye  com- 
pounds of  the  same  order,  forming  the  BrofnitM-9dU$  of  Bonsdoxff. 

C.  With  Orgmoie  Sabstanees:   as  alcohol,  ether,  camphor,  starch. 
Bromine  is  alao  a  constituent  of  eertaia  artificial  organic  eomponnds. 


388  CHLORINE. 

Chaptbb  X. 

CHLORINE 


Chlorine  in  general, 

Scbeele.     Optuc.  I,  247. 

Weetrumb.     Crell.  Ann.  1790,  1,  3. 

Berthollet.    Mem.  de  VAcad.  d.  Se.  d  Paris,  1785,  276 ;  also  CreU.  Chem. 

Ann.  1790,  2,  444.— ^Inn.  Chim.  80,  54;  also  Gilb.  42,  299. 
Chenevix.     Nicholson's  J.  of  Nat.  Phil  1802,  171  and  229;    aLso  ^. 

GeM.  1,  583;  abetr.  GUb.  12,  416. 
Sir  Humphry  Davy.     Phil,  Trans.;  1809, 1;  91,  1810,  II.  231;  and  1811, 

I.  1;  also  Schw.  3,  79,  93,  95,  205,  and  256;  also  GHh.  35,  460;  36, 

188;  39,  3,  43,  and  90.     Further  :  OUb.  45,  117. 
Gay-Lussac  &  Th^nard.     Becherches,  2,  93.— if^.  d^Arcueil,  2,  357; 

abstr.  QHh.  35,  8. 
Oay-Lussac.     Ann.  Chim.  91,  96;  also  Schw.  14,  79« 
Berzelins.     Gilb.  37,  458;  38,  217  and  227;  42,  288  and  299. 
Friedr.  Graf  von  Stsuiion.     Oxide  of  Chlorine  and  Perchloric  acid,     Gilb. 

52,  197  and  339. 
H.  Davy  k  Faraday,  Liquid  Chlorine.     Phil.  Trans.  1823, 160  and  198; 

also^nn.  Phil,  5,  304  and  393;  also  Kastn.  Arch.  1,  89;  absir. 

Schw.  38,  116. 
Faraday.     Hydrate  of  Chlorine.     Qu.  J.  ofSc,  15,  71;  also  Kastn.  Arch. 

1,  89;  abstr.  Schw.  38,  116  and  301. 
HypoMorous  Add  and  Bleaching  Salts.     Berthollet.     Stat.  Chim,  2, 183; 

alBoA.Gehl.   1,631. — ^Wagenmann.     &t^.  35,  115. — ^Geiger.     Be- 

pert.  15,  40. — Mag.  Pharm.  8,  79. — Robiquet.     J.  Pharm.  10, 93. — 

Grouvelle.     Ann.  Chim.  Phys.  17,  37;   also  Schw.  33,  428. — Bene- 

liu3.     Pogg.  12,  529. — Liebig.     Pogg.  15,  441. — Soubeiran.     Ann. 

Chim.  Phys.  48,  113;  also  J,  Pharm.  17,  657;  18,  1;  also  Ann, 

Pharm,  1,  257. — Balard.     Ann.  Chim.  Phys.  57,  225;  abstr.  Ann. 

Pharm.  14,  167  and  298;  abstr.  J.  pr.  Chem.  4,  152. — Martens. 

Ann.  Chim.  Phys.  61,  193;  also  J.  pr.  Chem.  8,  264. — ^Gay-Lussac. 

Compt.  Bend.  14,  927. — Dotmer.     Ann.  Pharm.  38,  31. 
Oxide  of  Chlorine,     Count  Stadion  (vid.  sup.) — H.  Davy.     Phil.  Trans. 

1815,  214;    also  Ann.   Chim.    Phys.    1,   76. — Gay-Lussac.    Ann. 

Chim.  Phys.  8,  408. 
Chloric  Acid,     Vauquelin.     Ann.  Chim.  95,  91;  also  Gilb,  52,  295;  also 

N.  Tr.  1,  1,  242;    1,  2,  268.— Serullas.     Ann.  Chim.  Phys.  45,  204 

and  270. 
Percfdoric  Acid.     Count  Stadion    (vid.   mp.) — Serullas.     Ann.    Chim. 

Phys.  45,  270  ;  also  J.  Chim.  Med.  7,  97;  also  Pogg.  21,  164. — 

Ann.  Chim,  Phys.  46,  294,  297  and  323;  also  Pogg.   22,   289.— 

Mitscherlich.     Pogg.  25,  298. 
Compounds  of  Chlorine  and  Oxygen.  Millon.     N.  Ann.  Chim.  Phys.  7, 

298;  also  Ann.  Pharm.  46,  281. 
Hydrochloric  Acid.  Will.  Henry.  PhU.  Trans.  1800, 188;  also  Scher.  J. 

5,  439;  abstr.  GUb.  7,  265.     Phil.  Trans.  1812,  238;  also  Gilb,  47, 

237. 


CHLORINE.  289 

Phosgene;  J.  Davy,  Phil.  Trans.  1812,  144;  2l\bo  Schw.  3,  429;  9,  199; 

also  Gilb.  40,  220;  43,  296. 
Chloride  of  Boron;  Berzelius,  Pogg.  2,  147. — Dumas,  Ann.  Chim.  Phys. 

81,436;  83,376. 
Chloride  of  Pho^horus;  Gay-Lussac  &  Thenard.  Becherches,  2,  176. — H. 

Davy,    Schw.  3,  83  and  98;   GUh.  39,  6. — Berzelius,  Ann.  Chim. 

Phys.  2,  224.— Serullas,  Ann.  Chim.  Phys.  42,  25;  abo  Schw.  57, 

366;  also  Pogg.  17,  161. 
Oocy-chloride  of  Phosphorus;  Wurtz,  N.  Ann.  Chim.  Phys.  20,  472;  abstr. 

Ann.  Pharm.  64,  245. 
Chloride  of  Sulphur;  Thomson,  Nichols.  J.  of  NaJt.  PhU.  6,  96;  also  iT. 

Oehl.  6,  333.     Ann.  Phil.  15,  408;  also  N.  Tr.  5,  2,  322.--H.  Davy, 

EUm.  d.  Chem.  TheUs  d.  Naturwissenschafty  253. — A.  Berthollet, 

M&m.  d'Arcueil,  1,  161;  also  N.  Oehl.  6,  352.— Bucholz,  N.  Oehl. 

9,  172.— Ridolfi,  Schw.  22,  303.— Gaultier  de  Claubry,  Ann.  Chim. 

Phys.  7,  213.— Dumas,  Bullet.  Philom.  d.  Sc.  1825,  23.— ^nn.  Chim. 

Phys.  49,  204;  also  Schw.   65,  81.— H.  Rose,  Pogg.  21,  431;  24, 

303;  27,  107;  42,  517  and  542.— Martens,  J.  Chim.  Med.  13,  430. 

— Millon,  Compt.  Bend.  6,  207;  also  J,  pr.  Chem.  16, 57. — Marohand, 

J.  pr.  Chem.  22,  507. 
Sulphate  of  Chloride  of  Sulphur;  H.  Rose,  Pogg.  44,  291;  46,  167;  52, 

69. — Regnault,  Ann.  Chim.  Phys.  69,  170;  71,  445;  also/,  pr.  Chem. 

18,  93;  19,  243. 
Chloride  of  Selenium;  Berzelius,  Ann.  Chim.  Phys.  9,  225. 
Chloride  of  Iodine ;  Gay-Lussac,  Ann.  Chim.  91,  5;  also  GUh.  49,  8.— 

Serullas,  Ann.  Chim.  Phys.  22,  185;  38,  387;  43,  208;  (also  J.  Chim. 

Med.  6,  336;  Pogg.  18,  116;  N.  Tr.  21,  2,  256;  45,  59,  199,  and 

270;  also  J.  Chim.  Med.  7,  9  and  93;  also  Pogg.  21,  164;  46,  294. 

— Soubeiran,  J.  Pharm.  23,  49. — Kane,  Phil.  Mag,  J.    10,   430; 

abstr.  J.  pr.  Chem.  11,  250. 
Metallic  Chlorides  and  HydrochlorcUes ;  Val.  Rose.     Atomic  proportions, 

A.  Oehl.   6,  22.— Gay-Lussac  &   Thenard,   Becherches,  2,  94.— H. 

Davy,  Gilb.  39,  43.— J.  Davy,  Schw.  10,  311.— A.  VogeL     Beha- 
viour of  Chlorides  vdth  Sulphuric  add,  Schw.  32,  51. 


Chlorine,  Halogen;  Oxy-muriatic  acid.  Oxidated,  Oxygenated,  Dephlo^ 
gisticated  Muriatic  Acid,  Bleaching  Acid;  Chlore,  Acide  muriatique  oxir 
g&ni;  Chlorum,  Acid  muriaticum  oxigenatum.  In  the  gaseous  state; 
Chlorine  gas,  Chlorgas,  Oxy-muriatic  acid  gas,  Zundendes  Salzgcu,  Gas 
acide  muriatique  oxighU. 

History.  From  common  salt,  a  substance  known  from  the  earliest 
times,  the  alchemists  appear  first  to  have  obtained  il^t^^otM  Muriatic  Add. 
Priestley,  with  his  mercurial  pneumatic  trough,  discovered  Muriatic  acid 
gas.  By  treating  manganese  with  muriatic  acid,  Scheele,  in  1774,  first 
obtained  chlorine  gas,  which,  in  accordance  with  the  existing  doctrine  of 
phlogiston,  he  regarded  as  Depldogisticated  Muriatic  Acid.  Berthollet, 
in  1785,  showed,  that  in  accordance  with  the  antiphlogistic  system  of 
chemistry,  just  then  rising  into  favour,  this  substance  ought  to  be  regarded 
as  Oxygenated  Muriatic  Acid;  and  this  view  was  adopted  and  maintained 
its  ground  till  1809.  In  that  year,  however,  Gay-Lussac  &  Thenard, 
showed,  by  arguments  founded  on  numerous  experiments,  that  the  che- 
mical relations  of  chlorine  might  all  be  explained  on  the  supposition  of  its 

VOL.    II.  u 


290  CHLORINE* 

being  an  elementary  substance.  Sir  H.  Davy,  in  1810,  was  tbe  first  to 
give  the  preference  to  this  now  almost  unirersallj  adopted  theory:  be 
also  gave  to  the  substance  in  question  its  present  name  of  Ghlorinr. 

The  bleaching  compounds  obtained  by  bringing  chlorine  in  contact 
with  alkaline  solutions  were  known  as  early  as  the  time  of  Berthollet. 
They  were  long  regarded  as  chlorides  of  the  alkalis,  till  Berzelius  sug- 
gested the  idea  that  they  might  be  mixtures  of  metallic  chlorides  with 
alkaline  chlorites,  the  acid  of  which  probably  contained  3  atoms  of  oxygen 
to  1  of  chlorine. 

4KO  +  4C1  =  3KC1  +  K0,C10». 

Balard,  in  1834,  showed  that  the  bleaching  compounds  are  mixtures  of 
metallic  chlorides  with  alkaline  hjrpochlorites,  and  he  obtained  Hypo- 
chloroTM  acid  in  the  free  state.  In  1815,  Sir  Humphry  Davy  and  Connt 
Stadion  simultaneously  discovered  Oxidt  of  Chlorine  (also  called  Chlorous 
acid)t  which  had  previously  been  noticed  by  Ohenevix,  but  mistaken  for 
chloric  acid.  Berthollet  first  showed  how  to  prepare  some  of  the  chlorates : 
these  were  more  minutely  examined  by  Chenevix  in  1802;  and  in  1814 
Oay-Lussac  first  succeeded  in  isolating  Chloric  acid  from  them.  Per- 
chloric acid,  discovered  in  1815  by  Count  Stadion,  was  afterwards  more 
particularly  examined  by  Serullas. 

Chlorous  acid  (CIO*)  was  discovered  by  MiUon;  also  the  Chloro- 
chloric  and  Chloro-perchhric  acids  formed  by  the  union  of  chlorous  acid 
with  chloric  and  perchloric  acid  respectively. 

Phosgene  gas  was  discovered  by  John  Davy;  Chloride  of  Boron  by 
Berxelius,  in  1834;  Terchlaride  of  Phosphorus  by  Gay-Lussac  &  Thenard, 
in  1808;  PentaMoride  of  Phosphorus  by  Sir  H.  Davy;  OxychUmde  of 
Phosphorus  by  Wurtz;  Chloride  of  Sulphur  by  Hagenmann,  in  1781 
{Crell.  N,  Entd,  4,  74);  and  by  Thomson  in  1804;  a  compound  of  oxy- 
gen, chlorine,  sulphur,  and  carbon,  by  Berzelius  &  Marcet,  in  1813;  and 
several  others  (which,  however,  rather  belong  to  the  department  of 
organic  chemistry)  by  Kolbe;  Chloride  of  Selenium  by  Berzelius;  Chloride 
of  Iodine  by  Gay-Lussac ;  Chloride  of  Bromine  by  Balard.  The  charac- 
teristic properties  of  the  metallic  chlorides  were  especiaUy  examined  by 
Gay-Lussac  &  Thenard. 

Sources,  Chlorine  occurs  in  considerable  quantities  in  all  three  king- 
doms of  nature,  sometimes  as  hydrochloric  acid,  sometimes  as  sal-ammo- 
niac; also  in  the  chlorides  of  potassium,  sodium,  calcium,  magnesium, 
lead,  mercury,  and  silver,  and  in  certain  ores  of  copper. 

Preparation,  1.  In  the  gaseous  state,  (a.)  By  heating  manganese 
with  strong  hydrochloric  acid.  {Sch,  64  or  73.) 

MnO*  +  2HC1  =  MnCl  +  2HO  +  CI 
or:  MnO  +  2HC1  =  MnO,  HCl  +  HO  +  01. 

About  4  parts  of  aoid  are  required  for  1  part  of  manganese.  (5.)  By 
heskting  manganese  with  common  salt  and  dilute  sulphuric  acid.  {St^,  79.) 

MnO  +  NaCl  +  2S0»  =  MnO,  SOa  +  NaO,SO>  +  CI. 
The  proportions  required  are :  1  At.  manganese,  1  At.  common  salt,  and 
2  At.  sulphuric  acid;  but  it  is  better  to  use  ^^  At.  more  sulphuric  acid, 
as  otherwise  the  decomposition  is  not  complete  till  the  mass  becomes  dry. 
(Hesse.)  For  1  part  of  common  salt,  f  pt.  of  good  manganese  and  2 
parts  oil  of  vitriol  diluted  with  1  part  water  are  required :  if  the  manga- 
nese consists  of  hydrate  of  manganic  oxide  (Mn^O',HO),  the  proportions 


CHLORINS.  291 

are :  1  part  oommon  salt,  1  manganese^  and  2f  oil  of  vitriol  dilated  with 
balf  its  weight  of  water.  According  to  Dobereiner  {Schw.  63,  480)^ 
bisulphate  of  soda  mixed  with  water  does  not  liberate  chlorine  from  a 
mixture  of  common  salt  and  manganese  till  the  mixture  has  become  dry ; 
and  the  chlorine  thus  evolved  is  mixed  with  a  very  large  quantity  of 
vapour  of  chloride  of  manganese.  Hesse  {Ann,  Pharm.  d>  61)  combats 
this  statement;  and  the  author's  experiments  also  show  that  this  mixture 
evolves  abundance  of  chlorine  Ions  before  it  becomes  dry.  The  more 
finely  the  manganese  is  pounded,  the  more  completely  is  it  decomposed 
before  drying. 

The  gas  obtained  by  either  of  the  preceding  methods  may  be  conta- 
minated with  hydrochloric  acid  gas  and  vapour  of  chloride  of  manganese. 
To  free  it  from  these  impurities,  it  may  be  washed  by  passing  it  through 
a  bottle  containing  water  {App,  43).  It  is  collected  over  hot  water^ 
inasmuch  as  cold  water  absorbs  it  abundantly. 

IT  For  preparing  chlorine  on  the  large  scale  (as  for  the  manufacture 
of  bleaching-powder),  a  new  process  has  lately  been  introduced  by 
Mr.  Dnnlop,  in  which  the  use  of  oxide  of  manganese  is  superseded  hj 
nitric  acid.  1  At.  nitric  acid  yields  2  At.  oxygen  to  the  hydrochloric 
acid,  whereby  it  is  converted  into  nitrous  acid,  and  causes  the  evolution 
of  2  At.  chlorine. 

NO»  +  2HC1  ==  NO'  +  2HO  +  2C1. 

The  economy  of  the  process  consists  in  absorbing  the  nitrous  acid  vapour 
by  sulphuric  acid,  and  introducing  the  nitrous  acid  in  this  form  into  the 
ledden  chamber,  {GrakanCB  Chemigtry,  New  Ed,  page  460.) 

Another  manufacturing  process,  which  has  been  patented  in  this 
country,  consists  in  burning  the  hydrogen  of  hydrochloric  acid  at  the 
expense  of  the  oxygen  of  the  air,  whereby  a  mixture  of  chlorine  and 
nitrogen  gases  is  obtained.  The  hydrochloric  acid  gas  mixed  with  air 
is  introduced  into  a  chamber  containing  red-hot  bricks,  and  the  resulting 
gaseous  mixture  passed  through  water  to  remove  nndecomposed  hydro- 
chloric acid.  The  chlorine  thus  obtained  serves  for  the  manufacture  of 
chloride  of  lime.  (Oxland,  Berz,  Jahreih.  26,  136.^     IT 

2.  In  the  liquid  itate,  a.  Hydrate  of  chlorine  is  put  into  a  strong 
fflass  tube,  the  tube  sealed,  and  heated  to  38°  (100°  F.).  The  hydrate 
fuses  and  divides  itself  into  two  strata;  the  upper  of  these,  which  occu- 
pies three-fourths  of  the  whole,  is  water  coloured  bv  a  small  quantity  of 
chlorine ;  the  lower  is  liquid  chlorine.  If  the  tube  is  bent  with  two  arms, 
the  chlorine  may  be  distilled  from  one  to  the  other,  and  thus  separated 
from  the  water.  (H.  Davy  &  Faraday.)  Chlorine  gas  is  passed  into  20 
grammes  of  water  contained  in  a  cylindrical  vessel,  and  kept  at  a  tempe- 
rature between  0°  and  V,  till  the  water  is  converted  into  a  stiff  paste. 
The  whole  is  then  thrown  upon  a  filter,  to  remove  the  excess  of  water — 
the  hvdrate  of  chlorine  pressed  between  bibulous  paper,  which  is  fre- 
quently changed — then  removed  from  the  filter  by  means  of  a  wooden 
spatu^  and  divided  upon  a  glass  plate  into  strips :  in  this  form,  it  is 
thrust  into  the  tube,  which  is  held  for  the  purpose  close  to  the  edge  of 
the  glass  plate.  All  these  operations  must  be  performed  as  quickly  as 
possible,  and  at  a  temperature  only  a  little  below  0°;  for  at  —4°  the 
hydrate  freezes  fast  to  the  filter.  The  sides  of  the  glass  tube  should  be 
half  a  line  in  thickness,  its  width  3^  lines,  and  its  length  at  the  com- 
mencement of  the  operation  4  inches.  Before  the  hydrate  is  introduced, 
the  tube  must  be  drawn  out  a  little,  a:bout  2^  inches  from  the  sealed  end. 
The  hydrate  of  chlorine  is  firmly  pressed  iti  with  a  ramrod  to  tlie  thick- 

V  2 


292  CHLOKINE. 

ness  of  1^  inch.  The  tube  is  then  inserted  through  a  eork  nearly  as  hr 
as  the  part  which  has  been  drawn  out — introduced  into  a  vessel  filled 
with  a  freezing  mixture,  so  that  the  mouth  of  the  vessel  may  be  closed 
by  the  cork— drawn  out  at  the  narrow  part  into  a  long  neck — cut  off  at 
that  part — the  sides  of  the  neck  thickened  in  the  flame  of  a  lamp,  with- 
out actually  sealing  it — the  tube  left  to  cool — then  taken  for  a  few  seconds 
out  of  the  freezing  mixture — then  immersed  in  a  fresh  mixture,  and 
strongly  sealed  at  the  moment  when  the  gas  within  it  begins  to  contract. 
(Biewend,  J.  pr.  Chem.  15,  440.)— 6.  Chlorine  gas  dried  by  oil  of  vitriol 
may  also  be  liquefied  by  pressure  and  cooling.  (H.  Davy  &  Faraday.)— 
c.  Fuming  hydrochloric  acid  and  peroxide  of  manganese  are  sealed  up 
together  m  a  bent  tube.  At  ordinary  temperatures,  a  yellow  film  of 
liquid  forms  between  the  manganese  and  the  acid;  and  if  the  empty 
arm  of  the  tube  is  cooled  10  lower,  this  liquid  distils  over  into  it. 
(Niemann,  Br.  Arch,  36,  18.)— </.  The  longer  arm  of  a  bent  glass  tube 
is  three-fourths  filled  with  an  intimate  mixture  of  previously  fused  bisnl- 
phate  of  potassa,  dried  common  salt,  and  manganese;  upon  this  is  placed 
a  layer  1^  inch  thick  of  pieces  of  chloride  of  calcium;  the  shorter  and 
empty  arm  of  the  tube  is  sealed,  and  the  longer  arm  inserted  into  a  gun- 
barrel,  which  is  heated  by  coads  heaped  around  it,  while  the  short  arm 
is  kept  cool.  Liquid  chlorine  distils  over  into  the  latter,  and  when  the 
longer  arm  cools,  is  not  absorbed  by  its  contents.  This  process  may  be 
performed  in  summer.  (Mohr,  Ann,  Pharm,  22,  162.) 

Tubes  containing  liquid  chlorine  must,  if  they  likewise  contain  water 
(as  when  process  a  is  adopted),  be  kept  in  the  dark ;  otherwise  the  water 
will  be  decomposed  and  oxygen  gas  evolved,  which  will  burst  the  tube. 

Properties.  1.  In  the  liquid  state.  Transparent,  of  a  dark  greenish- 
yellow  colour  (pure  yellow — Niemann),  very  fluid;  specific  gravity 
=  1-33;  does  not  solidify  at  —  17-8°  (0^  F.)  [nor  at  —  220^  F.  (Nat- 
terer)] ;  its  refracting  power  is  less  than  that  of  water.  (H.  Davy  & 
Faraday.)  Does  not  conduct  electricity  (Solly;  Kemp);  does  not  attack 
the  platinum  electrodes ;  bleaches  diy  litmus-paper.  (Kemp.) 

2.  In  the  gaseous  fmin,  [^Tension,  sjpecific  gravity,  and  refracting 
power  (I.,  261,  279 — 95).]  Liquid  chlorine,  when  the  vessel  containing 
it  is  opened,  is  instantly  converted  into  gas:  a  small  portion,  however, 
is  retained  for  a  while  in  the  liquid  state,  in  consequence  of  the  in- 
tense cold,  probably  amounting  to  —  40""^  produced  by  the  sudden 
evaporation  of  the  other  part.  (Faraday.)  Pale  yellow  gas  (the  denser 
gas  which  rests  immediately  on  the  surface  of  liquid  chlorine  b  orange- 
yellow,  not  greenish-yellow).  When  perfectly  dry,  it  neither  freezes  nor 
liquefies  at  a  temperature  of  —40^  (H.  Davy.)  Incombustible:  a  wax 
taper  plunged  into  it  continues  to  burn  with  a  feeble  light,  and  copious 
deposition  of  soot :  if  introduced  into  the  gas  with  a  glowing  wick,  it  is 
rekindled.  (Trevelyan,  Phil.  Mag,  J.  3,  72.)  A  burning  slip  of  wood 
continues  to  burn  in  the  gas  for  a  short  time  only,  and  with  a  very  feeble 
flame.  Chlorine  gas  in  the  moist  state  destroys  vegetable  colours,  with- 
out previously  reddening  any  of  them — litmus,  for  example.  Since  the 
dry  gas  has  no  action  on  dry  litmus-paper,  it  would  appear  that  the 
liquid  state — whether  produced  by  compression  or  by  water — is  essential 
to  this  action.  (Kemp.)  Chlorine  destroys  organic  odours  and  infectious 
matters  (antimiasmatic  fumigation);  has  a  very  pungent  and  suffocating 
odour,  when  inhaled,  even  in  small  Quantity,  it  excites  sneezing,  cough* 
ing,  oppression^  and  choking;  and  if  irequently  inhaled,  spitting  of  blood 
and  fainting. 


HYDRATE  OF  CHLORINE.  293 

Atomic  weight  of  chlorine:  35*48,  H  =  1,  or  442-66  0  =  1  (the 
doable  atom,  Berzelius);  36  (Marignac,  Compt  Rend,  14,  570);  35*46, 
H  =  ],  or  443-28,  0  =  I  (Marignac,  Berz,  Jdhresh.  25,  33);  3549, 
H  =  1,  or  443*660  (Maumene,  N.  Ann.  Ckim.  Fkys,  18,  41).  Laurent 
(Compt,  Rend,  14,  456)  conclades  from  his  own  analyses  that  the 
number  given  by  Berzelius  is  the  correct  one. 


Compounds  of  Chlorine, 
Chlorinb  and  Water. 


A.  Hydrate  of  Chlortne.  When  chlorine  is  brought  in  contact 
with  water,  at  a  temperature  a  little  below  O'',  the  two  bodies  unite  and 
form  a  solid  mass.  The  compound  is  obtained  in  a  state  of  purity  by 
introducing  into  a  vessel  filled  with  chlorine  gas  a  quantity  of  water  not 
sufficient  to  convert  the  whole  into  hydrate,  and  exposing  the  vessel  for 
some  days  to  a  temperature  of  0^  Arborescent,  crystalline,  pale  yellow, 
translucent  mass,  having  a  density  of  1*2,  according  to  Faraday,  and 
sometimes  crystallizing  in  needles  and  rhombic  octohedrons.  Sometimes 
dendritic,  sometimes  granular,  sometimes  in  crystals,  which  appear  to 
belong  to  the  regular  system.  (Biewend.)  May  be  sublimed  from  one 
part  of  the  vessel  to  another.  (Faraday.)  Does  not  conduct  electricity. 
(Solly.) 

Calcalation.  Faraday. 

CI    35-4  28-23  27*7 

lOHO     90      71-77  72-3 

C1,10HO 125-4  100-00  100-0 

Remains  unaltered  in  the  sealed  tube  at  +  15*5°  (and  even  at  +  20^, 
Bio  wend);  is  resolved  at  38^  into  chlorine-water  and  free  chlorine,  which 
separates  as  a  distinct  liauid  stratum.  On  subsequent  cooling  to  21°, 
(often  not  till  cooled  to  0  ,  and  imperfectly  when  at  rest,  Biewend),  the 
two  strata  combine,  and  reproduce  the  crystalline  hydrate.  (Faraday.) 
When  exposed  to  the  air,  and  gently  warmed,  the  hydrate  is  resolved, 
with  slight  effervescence,  into  gaseous  chlorine  and  chlorine-water.  The 
hydrate  acts  on  ammonia,  ammoniacal  salts,  and  alcohol,  in  the  same 
manner  as  free  chlorine.  (Faraday.) 

B.  Aqueous  Solution  of  Chlorine.  Chlor'ine-water,  Liquid 
Oxymuriatic  acid.  Water  at  ordinary  temperatures  absorbs  about  twice 
its  volume  of  chlorine  gas.  (Dal ton.)  The  solubility  of  chlorine  in  water 
increases  from  0°  to  9°,  because,  at  this  latter  temperature,  the  chlorine 
is  still  in  the  state  of  hydrate ;  but  from  this  point  upwards  the  solubility 
continually  diminishes,  and  at  100""  is  almost  nothing.  (Qay-Lussac. 
jinn,  Chim.  Pkys,  70,  407.)  Pure  water  at  15°  absorbs  rather  more 
than  twice  its  volume  of  chlorine  gas ;  but  water  saturated  with  chloride 
of  potassium  takes  up  one-third  less.  Water  saturated  with  chlorine  at 
6°  (42-8°  F.)  has  a  specific  gravity  of  1*003.  (Berzelius.)  It  is  yellowish, 
has  the  odour  of  the  gas,  and  tastes  not  acid,  but  bitter.  Freezes  at  about 
0^,  and  is  then,  according  to  Faraday,  resolved  into  hydrate  of  chlorine, 
and  ice  which  is  free  from  chlorine.  It  is  gradually  decomposed,  espe* 
cially  when  exposed  to  light,  into  aqueous  hydrochloric  acid  and  oxygen 


294  CHLORINE. 

gas.  Whether  the  chlorine  dissolres  in  the  water  without  alteration,  or 
whether  it  is  first  converted,  on  the  one  hand,  into  hydrochloric  acid  by- 
taking  oxygen  from  the  water,  and,  on  the  other,  into  hypochlorous  acid 
by  tSking  oxygen  from  the  water,  is  a  Question  which  must  for  the 
present  remain  undecided.  At  all  events,  the  liquid  has  the  same  odoar, 
and  exhibits  in  other  respects  the  same  characters  as  the  gas  itself. 

Chlorine  and  Oxtoen. 

The  affinity  of  chlorine  for  oxygen  is  even  feebler  than  that  of  iodine 
and  bromine  for  the  same  element ;  the  two  bodies  cannot  be  made  to 
combine  directly. 

A.    Hypochlobovb  Acid.    CIO. 

Acide  Jfyperchloreux,  UrUerchlorige  Saure, 

Formation.  1.  Chlorine  and  mercuric  oxide  form  protochloride  of 
mercury  (or  oxyohloride,  if  the  oxide  is  in  excess),  and  hypochlorous 
acid.  (Balard;  (^y-Lussac.) 

Hgo  +  2C1  =  Hgci  +  ao. 

Tf  the  oxide  of  mercury  be  digested  in  chlorine-water,  ^  of  the  liquid 
distilled  off,  and  ^  of  water  added  to  the  distillate,  the  mixture  so  formed 
possessses  the  same  degree  of  bleaching  power  as  the  orifi;inal  solution, 
although  the  quantity  of  chlorine  contained  in  it  is  only  half  as  great, 
one  half  of  the  bleacning  power  being  in  fact  due  to  the  oxygen.  (Gay- 
Lussac.) — 2.  When  chlorine  is  brought  in  contact  at  ordinary  tempera- 
tures with  aqueous  solutions  of  the  alkalis,  and  a  few  other  of  the 
stronger  bases,  or  with  the  compounds  of  these  bases  with  the  weaker 
acids,  as  carbonic  or  acetic  acid,  the  chlorino  not  being  in  excess,  a 
metallic  chloride  and  a  salt  of  hypochlorous  acid  are  produced. 

H  3.  By  the  action  of  chlorine  on  various  salts.  When  chlorine  is 
passed  into  a  solution  of  terbasic  phosphate  of  soda  (3NaO,  cPO*)  till  it 
IS  no  longer  absorbed,  a  liquid  is  obtained,  having  strong  bleaching  pro- 
perties, and  yielding  hypochlorous  acid  when  distilled ;  the  residue  in  the 
retort  has  a  strong  acid  reaction,  and  appears  to  consist  of  a  mixture  of 
1  At.  phosphate  of  soda  and  2  At.  chloride  of  sodium.  Similar  results 
are  obtained  with  the  ordinary  phosphate,  and  the  bibasic  pyrophosphate 
of  soda,  excepting  that  the  latter  gives  up  only  one  atom  of  base.  The 
normal  sulphates  of  soda,  sesqui-oxide  of  iron,  oxide  of  zinc,  protoxide  of 
manganese,  and  protoxide  of  copper,  and  the  double  sulphate  of  alumina 
and  potassa>  yield  a  distillate  of  hypochlorous  acid,  and  a  residue  consist- 
ing of  chloride  and  acid  sulphate;  even  sulphate  of  lead  is  slightly  decom- 
posed. Nitrate  and  chromate  of  potassa  also  yield  hypochlorous  acid, 
when  treated  with  chlorine.  (Williamson,  Ann.  Pharm.  54,  1 42.)1F 

Preparation.  In  the  gaseous  state.  1 .  Finely  pounded  mercuric  oxide  (or 
sulphate,  Gay-Lussac,)  diffused  through  12  times  its  weight  of  water,  is  in- 
troduced into  a  bottle  filled  with  chlorine  gas — the  bottle  shaken  till  the 
chlorine  is  absorbed,  which  soon  takes  place — the  solution  of  hypochlorous 
acid  immediately  filtered  from  the  brown  oxychloride  of  mercury,  and  puri- 
fied by  distillation  in  vacuo.  The  acid  solution  thus  obtained  is  weak, 
but  may  be  concentrated  by  repeated  fractional  distillation  of  tiie  portion 


HYPOCHLOROUS  ACID.  295 

which  firat  parses  over.  The  aqueous  solution  having  been  concentrated 
in  this  manner^  as  far  as  possiole^  the  anhydrous  gaseous  acid  maj  be 
obtained  from  it,  by  introducinff  the  liquid  into  a  receiver  filled  with, 
and  standing  over  mercury,  and  adding  by  degrees — so  as  to  avoid  any 
rise  of  temperature,  which  would  cause  an  explosion — ^about  an  equal 
volume  of  dry  nitrate  of  lime,  or  glacial  phosphoric  acid  (which  latter  must 
be  free  from  ammonia,  and  consequently  must  not  have  been  prepared 
from  phosphate  of  ammonia).  The  gas  is  evolved  with  effervescence, 
and  the  solution  of  nitrate  of  lime,  or  phosphoric  acid,  which  is  produced, 
protects  it  from  the  decomposing  action  of  the  mercury.  (Balard.)  Gay- 
Lussac  found  that  this  method  yielded  but  a  very  indifferent  result,  when 
nitrate  of  lime  was  used. — 2.  A  bottle  of  the  capacity  of  100  —  150 
cubic  centimetres  having  been  filled  with  perfectly  dry  chlorine  gas,  ik 
glass  tube  closed  at  the  bottom,  two-thirds  filled  with  dry  mercuric  oxide, 
and  above  that  with  dry  fine  sand,  is  introduced  into  it — ^the  bottle  closed 
with  a  glass  stopper,  the  upper  third  of  which  is  smeared  with  tallow,  so 
that  the  mouth  may  be  completely  closed,  but  the  gas  may  not  act  upon 
the  tallow — and  shaken,  so  that  the  sand  and  oxide  may  fall  out  of  the 
tube,  and  the  oxide  may  act  on  the  gas.  In  a  few  minutes,  the  chlorine 
IS  decolorized,  and  converted  into  half  its  bulk  of  hypochlorous  acid  ^. 
If  the  stopper  be  removed  under  mercury,  the  mercury  enters  and  fills 
one-half  of  the  bottle;  water  absorbs  the  gas  suddenly  and  almost  com- 
pletely. But  the  excess  of  mercuric  oxide  often  exerts  a  decomposing 
action  on  the  gas,  and  liberates  oxygen  from  it.  (Gay-Lussac^ 

IT  According  to  Gay-Lussac,  the  mercuric  oxide  prepared  in  the  wet 
^^7;  ^'  ff'  by  precipitation  with  caustic  potash,  is  best  adapted  for  this 
process,  and  tne  gas  produced  by  its  action  upon  chlorine  is  colourless, 
relouze,  however,  finds  that  the  oxide  thus  prepared  acts  with  such  vio- 
lence on  chlorine  as  to  cause  a  considerable  rise  of  temperature,  whereby 
the  hvpochlorous  acid  is  decomposed,  and  the  only  products  obtained  are 
chloride  of  mercury  and  oxygen  gas.  But  if  the  oxide  of  mercury,  before 
being  used,  is  strongly  heated  in  a  sand-bath  (the  temperature  being  of 
course  kept  below  the  decomposing  point)  it  afterwards  acts  less  forcibly 
and  without  causing  rise  of  temperature,  and  yields  chloride  of  mercury 
and  hypochlorous  acid  gas :  moreover,  the  gas  thus  obtained  is  not  colour- 
less, but  has  a  yellow  tint,  inclining  more  to  red  than  that  of  chlorine. — 
3.  Hypochlorous  acid  gas  may  be  ootained  at  once  in  the  anhydrous  state 
by  passing  dry  chlorine  gas  over  mercuric  oxide  contained  in  a  glass  tube 
surrounded  with  fragments  of  ice  or  immersed  in  cold  water.  Chloride  of 
mercury  is  then  formed,  and  hvpochlorous  acid  disengaged  in  the  form  of 
a  yellow  gas,  which  may  be  collected  over  mercury.  It  cannot,  however, 
be  kept  over  mercury,  as  it  is  gradually  decomposed  by  that  liquid;  it 
must  therefore  be  collected  in  stoppered  bottles,  having  the  upper  part 
of  the  stopper  smeared  with  grease,  each  bottle  being  removed  as  soon  as 
it  is  filled;  or  the  gas  may  be  collected  by  displacement  in  a  series  of  bot- 
tles connected  together,  the  portion  which  issues  from  the  last  being 
absorbed  by  water,  so  that  none  may  be  wasted.  The  oxide  of  mercury 
used  in  this  process  must  be  prepared  by  precipitation  with  caustic  potash 
and  dried  at  SOO"*  (572®  F.).  The  red  oxide  obtained  by  igniting  the 
nitrate  or  by  prolonged  ebullition  of  mercury  is  not  acted  on  by  dry  chlo- 
rine. (Pelouze,  iT.  Ann.  Chim.  Phy$.  7,  179.) 

h.  In  the  liquid  state.  Dry  hypochlorous  acid  gas,  obtained  by 
Pelouze's  method  (3),  is  passed  into  a  i7-tub©  eooled  to  —  20*»  (-4^  F.). 
(Pelouze). 


296  CHLORINE. 

Properties  of  the  liquid  acid.  Deep  orange-coloured  liquid,  heavier 
than  water.  Does  not  boil  or  volatilize  till  heated  to  21*  (698°  F.). 
Nevertheless,  it  is  apt  to  explode  with  violence  even  while  surrounded 
with  a  freezing  mixture;  hence  great  care  is  requisite  in  manipulating 
with  it.  Does  not  alter  the  metaUic  Instre  of  antimony.  When  thrown 
into  water  it  first  sinks  to  the  bottom,  and  then  dissolves,  provided  the 
water  is  in  sufficient  quantity.  If  not,  a  yellow  saturated  solution  is 
formed  above  the  part  which  remains  undissolved.  If  the  saturated  solu- 
tion be  diluted  with  water,  its  colour  becomes  fainter,  and  ultimately  dis- 
appears altogether.  (Peloaze.)  IT 

Of  the  Gas,  Yellow,  not  much  darker  than  chlorine  (Balard^ ;  yel- 
low, somewhat  inclining  to  red  (Pelouze) ;  colourless  (Gay-Lussac) ;  vid, 
p.  295.  Of  very  powerful  odour,  more  resembling  that  of  chlorine  than 
that  of  chloric  oxide,  but  different  from  both.  (Balard.) 

CalculatioD^  according  to  Balard.  Vol.  Sp.  gr. 

a 35-4  81-6  Chlorine  gaa    I  2*4543 

O    80  18*4  Oxygen  gas     \  05546 

CIO 43-4  100-0  Hypochlorousacidgas.  1  3*0089 

Decompositions,  1.  One  volume  of  the  gas  is  resolved  by  heat,  with 
explosion  and  development  of  light,  into  a  mixture  of  1  volume  of  chlorine 
gas  and  a  half  volume  of  oxygen.  The  temperature  required  to  explode 
it  is,  at  most,  a  little  higher  than  that  required  to  explode  chloric  oxide ; 
but  sometimes  it  explodes  while  being  transferred  from  one  vessel  to 
another.  (Balard.)  According  to  Gay-Lussac,  it  detonates  very  easily, 
sometimes  even  at  ordinary  temperatures.  When  exposed  to  sunshine,  it 
is  decomposed  in  the  course  of  a  few  minutes,  in  the  same  manner,  but 
without  detonation.  In  diffused  daylight  it  remains  unaltered  for  some 
hours. 

2.  When  mixed  with  hydrogen  it  explodes  violently  on  the  approach 
of  a  burning  body,  and  forms  a  white  cloud  of  hydrated  hydrochloric  acid« 
Charcoal  causes  the  gas  to  explode  at  ordinary  temperatures,  probably  in 
consequence  of  the  heat  produced  by  absorption;  the  resulting  gaseous 
mixture  contains  a  small  quantity  of  carbonic  acid,  besides  chlorine  and 
oxygen.  Hypochlorous  acid  gas  mixed  with  carbonic  oxide  is  converted 
in  a  few  hours  into  phosgene  gas  (and  carbonic  acid?).  Aqueous  hypo- 
chlorous  acid  is  not  decomposed  either  by  charcoal  or  by  carbonic  oxide. 

liorus 
I  aqueous  acid,  it  forms  phosphoric  acid 
and  a  small  quantity  of  hydrochloric  acid,  with  evolution  of  chlorine. 
Hypophosphorous  and  phosphorous  acids  are  likewise  converted  into  phos- 
phoric  acid  by  contact  with  solution  of  hypochlorous  acid,  heat  being 
evolved  and  chlorine  gas  set  free.  Phosphuretted  hydrogen  explodes 
with  this  gas  at  ordinary  temperatures :  the  residual  gas  contains  chlorine 
with  a  small  quantity  of  oxygen.  With  the  aqueous  acid,  phosphuretted 
hydrogen  produces  phosphoric  and  hydrochloric  acid,  with  evolution  of 
chlorine.  The  ^as  explodes  by  contact  with  sulphur  at  ordinary  tem- 
peratures, emittmg  a  orilliant  light,  and  forming  sulphurous  acid  and 
chloride  of  sulphur,  whilst  part  of  the  chlorine  is  set  free.  When  sulphur 
is  digested  in  the  aqueous  solution  of  the  acid,  chlorine  is  evolved,  and 
sulphuric  acid,  together  with  a  small  quantity  of  chloride  of  sulphur,  pro- 
duced. A  mixture  of  hypochlorous  and  sulphurous  acid  gases  condenses 
in  a  few  hours,  with  formation  of  sulphuric  acid  (while  the  chlorine  com- 


HYPOCHLOROUS  ACID.  29? 

bines  with  tbe  mercury  over  whicli  the  gaseous  mixture  is  placed).  Sul- 
phurous acid  gas  passed  through  the  aqueous  solution  produces  sulphuric 
acid  and  liberates  chlorine.  Hydrosulphuric  acid  gas  produces  a  pale 
blue  flame  with  gaseous  hypochlorous  acid :  when  passed,  not  in  excess, 
through  the  aqueous  solution,  it  produces  sulphuric  acid  and  water,  with 
rise  of  temperature  and  evolution  of  chlorine  gas.  Bisulphide  of  carbon 
introduced  into  the  gas  at  ordinary  temperatures  produces  slight  detona- 
tion, and  forms  carbonic  acid,  sulphurous  acid,  and  chloride  of  sulphur, 
while  chlorine  is  set  free :  with  the  hydrated  acid  it  forms  carbonic,  sul- 
phuric, and  hydrochloric  acid.  Sulphide  of  phosphorus  introduced  into 
the  aqueous  solution  of  the  acid  produces  sulphuric,  phosphoric,  and 
hydrochloric  acid,  with  CYolution  of  chlorine  gas,  gentle  at  first,  but 
increasing  in  rapidity  as  the  temperature  rises.  Selenium  at  ordinary 
temperatures  causes  the  gas  to  explode  slightly:  in  the  solution,  it  is  con- 
verted into  selenic  acid,  with  evolution  of  chlorine.  Selenious  acid  is 
likewise  converted  into  selenic  acid  by  the  action  of  hydrated  hypochlo- 
rous acid.  Iodine  absorbs  the  gas,  producing  iodic  acid  and  chloride  of 
iodine:  when  put  into  the  solution,  it  causes  rise  of  temperature  and  evo- 
lution of  chlorine,  and  is  converted  into  iodic  acid,  together  with  a  small 
quantity  of  chloride  of  iodine.  Hydriodic  acid  gas  mixed  with  gaseous 
hypochlorous  acid  causes  rise  of  temperature  and  decomposition  :  hydriodic 
acid  gas  or  its  aqueous  solution  mixed  with  aqueous  hypochlorous  acid 
produces  iodic  acid,  with  rise  of  temperature  and  evolution  of  chlorine. 
Bromine  absorbs  the  eas,  producing  bromic  acid  and  chloride  of  bromine : 
from  the  solution  it  liberates  chlorine,  and  is  converted  into  bromic  acid. 
Hydrobromic  acid  water  mixed  with  excess  of  the  hydrated  acid  produces 
bromic  acid,  chloride  of  bromine,  hydrochloric  acid,  and  chlorine. 

3.  Hypochlorous  acid  gas  mixed  with  hydrochloric  acid  fas  yields 
water  and  chlorine :  it  has  no  action  on  nitrous  oxide :  it  explodes  with 
ammoniacal  gas,  and  the  aqueous  solution  mixed  with  aqueous  ammonia 
produces  water  and  chloride  of  nitrogen,  or  water,  nitrogen,  and  chlorine. 

4.  Potassium  burns  on  the  surface  of  the  aqueous  acid  without 
evolving  chlorine,  and  produces  chloride  of  potassium  and  hypochlorite 
of  potassa. 

2K  +  200  =  KCl  +  K0,C10. 

Arsenic  causes  the  gas  to  explode  with  a  vivid  light,  producing  arsenic 
acid  and  a  small  quantity  of  chloride  of  arsenic,  and  lioerating  chlorine 
gas.  Many  metals  wrapped  up  in  sized  paper  absorb  the  gas  rapidly, 
forming  an  oxide  and  a  chloride,  till  the  heat  evolved  by  the  action  causes 
the  gas  to  explode.  Silver-leaf  merely  forms  chloride  of  silver,  and  libe- 
rates oxygen,  till  the  heat  evolved  gives  rise  to  explosion.  Mercury 
absorbs  the  whole  of  the  gas,  with  the  exception  of  a  small  quantity  of 
oxygen,  and  forms  red  oxychloride  of  mercury.  Phosph  ide  of  calcium  causes 
the  gas  to  explode  violently,  with  separation  of  chlorine :  the  sulphides  of 
barium,  antimony,  tin,  and  mercury  produce  explosion  in  a  few  seconds, 
with  formation  of  chloride  of  sulphur.  The  aqueous  acid  converts  arsenic 
into  arsenic  acid  and  a  small  quantity  of  chloride  of  arsenic,  with  evolu- 
tion of  chlorine  gas;  dissolves  iron,  conyerting  it  into  sesqui-chloride,  and 
evolving  chlorine  gas  [oxygen  ?] ;  dissolves  copper,  converting  it  into 
protochloride,  with  evolution  of  cnlorine  and  a  small  quantity  [?]  of  oxy- 
gen ;  converts  mercury,  when  shaken  up  with  it,  almost  instantly  into 
oxy-chloride;  silver-filings  into  chloride  of  silver,  with  rapid  evolution  of 
oxygen  gas ;  does  not  act,  when  dilute,  upon  antimony,  bismuth,  zinc,  tin, 
or  lead^  excepting  in  presence  of  an  acid  which  can  form  a  soluble  salt 


298  CHLORINE. 

with  the  oxide  of  the  metal,  in  which  case  the  hypochlorona  acid  causes 
rapid  oxidation  of  the  metal  and  erolation  of  chlorine.  Concentrated 
hjpochloroos  acid  acts  ji^daallj  on  the  five  metals  jnet  mentioned, 
because  chloric  acid  is  produced  in  it,  and  this  supplies  the  place  of  sul- 
phuric or  nitric  acid.  Gold  and  platinum  are  not  attacked  by  aqueous 
hypochlorous  acid,  even  when  mixed  with  sulphuric  or  nitric  acid.  The 
aqueous  acid  conrerts  oxide  of  chromium  into  chromic  acid,  arsenioos  a4;id 
into  arsenic  acid,  and  the  protoxides  of  manganese,  tin,  lead,  cobalt  and 
nickel,  into  the  oorresponaing  oxides  of  the  highest  degree  of  oxidation, 
the  action  being  in  all  cases  attended  with  liberation  of  chlorine:  oxide  of 
silver,  on  the  other  hand,  is  converted  into  chloride,  with  erolation  of 
oxygen  gas  and  a  small  quantity  of  chlorine.  With  metallic  sulphides, 
the  aqueous  acid  forms  sulphates,  and  sometimes  also  chloride  of  sulphur, 
with  rise  of  temperature  and  erolution  of  chlorine.  With  the  chlorides  of 
the  alkali-metals  it  forms  alkaline  hyperchlorites,  with  which  a  small 
quantity  of  chloride  remains  mixed;  the  chlorides  of  manganese,  tin,  lead, 
iron,  cobalt,  and  nickel  are  converted  by  it  into  the  corresponding  highest 
oxides,  with  evolution  of  chlorine;  and  chloride  of  copper,  into  oxychlo- 
ride. 

5.  Hjrpochlorous  acid  decomposes  defiant  gas,  oxalic  acid,  cyanogen, 
hydrocyanic  acid,  paper,  litmus,  indigo,  and  many  other  organic  com- 
pounds.    White  unsized  paper  causes  the  gas  to  explode. 

Combmatiofu.  a.  With  Water:  Aqtieow  ffypoeMorous  Acid.  Water 
absorbs  the  gas  very  quickly,  probably  taking  up  more  than  100  times  its 
volume.  A  portion  of  chlorine  and  oxygen  gases  always  remains  behind, 
because,  in  the  preparation  of  the  gas  from  the  aqueous  acid,  partial  decom- 
position takes  place.  (Balard.)     Preparation  (p.  294). 

The  aqueous  acid  may  also  be  prepared  by  treating  common  chloride 
of  lime  with  very  dilute  "hydrochloric  acid  ana  distilling  :  the  acid  must 
be  added  in  successive  portions,  with  constant  agitation,  and  in  such 
quantity  as  to  saturate  less  than  half  the  lime.  (Gay-Lussac.)  IT  Or  chlo- 
rine gas  may  be  passed  into  water  in  which  nuefy  dividea  chaJk  is  sus- 
pended, whereupon  chloride  of  calcium  is  formed  and  dissolves,  and  hypo- 
chlorous  acid  is  set  free :  the  acid  may  then  be  separated  by  rapid  distil- 
lation. (^Williamson.)  IT  The  concentrated  acid  is  yellowish :  it  has  the 
odour  01  the  gas,  and  a  strong  but  not  acid  taste.  A  single  drop  of  if 
placed  upon  the  skin  produces  a  brown  stain,  and  destroys  the  epidermis 
in  the  coftrae  oi  half  a  minute:  it  eorrodes  more  deeply  than  nitric 
aeid. 

When  the  solution  is  exposed  to  the  air,  the  greater  part  of  the  acid 
volatilises.  At  100°,  only  a  small  portion  escapes  in  the  gaseous  form;  a 
mueh  larset  quantity  on  the  addition  of  nitrate  of  lime  or  glacial  phos- 
phoric acid :  oil  of  vitriol,  on  the  contrary,  separates  a  mixture  of  chloric 
oxide,  chlorine,  and  a  small  quantity  of  oxygen  gas.  The  aqueous  acid 
is  slowly  decomposed  in  the  dark,  more  auickly,  however,  in  proportion  as 
it  is  warmer  and  more  concentrated.  The  concentrated  acio,  oven  when 
surronnded  with  ice,  does  not  remain  unaltered  for  more  than  a  few  days : 
a  dilute  solution  resists  decomposition  for  a  longer  time.  The  decompo- 
sition produced  by  the  application  of  heat  is  not  immediate ;  hence  distil- 
lation is  possible.  When  decomposition  takes  place,  bubbles  of  chlorine 
gas  rise  through  the  liquid,  and  by  agitation  or  addition  of  pulverulent 
substances,  brisk  effervescence  takes  place :  the  residual  solution  consists 
of  chloric  acid.  (Balard.) 


4 


HTPSRCHLORITES.  299 

6C10  =■  Cl«  +  4a. 
The  aoid  when  heated  for  some  time  to  100°^  evolree  about  5  volumes  of 
chlorine  and  1  Yolume  of  oxygen,  and  leaves  chloric  acid.  (Gay-Lussac.) 
On  distilling  an  aqueous  acid^  which  has  a  bleaching  power  of  909°— chang- 
ing the  receiver  9  times,  so  as  to  obtain  9  distillates,  each  containinff  ^  of 
the  liquid,  and  leave  the  remaining  ^  in  the  retort— the  first  distillate  is 
found  to  have  a  bleaching  power  equal  to  2500^  the  second  1925^,  the 
third  1470°,  the  fourth  943^  the  fifth  624°,  the  sixth  400^  the  seventh 
222^  the  eij^hth  106°,  the  ninth  80^  and  the  residue  in  the  retort  0^ 
The  sum  of  these  decrees  divided  by  10  gives  822^;  consequently,  the 
acid  loses  only  87°  <»  bleaching  power  by  the  incipient  decomposition 
which  takes  place  during  distillation.  It  appears  as  if  the  decomposition 
took  place  only  where  the  liquid  is  in  contact  with  the  sides  of  the  vessel, 
while  the  inner  portions  sustain  the  boiling  heat  without  decomposition, 
and  volatilize  unchanged  within  the  gaa-bubbles,  consisting  of  chlorine 
and  a  little  oxygen,  which  are  ^nerated  at  the  sides  of  the  vessel.  When 
an  acid  of  1200^ — 1500°  bleaching  power  is  distilled,  the  decomposition  is 
much  more  considerable :  with  an  acid  of  600° — 70Qi^  bleaching  power,  on 
the  contrary,  it  is  very  small,  and  from  such  an  acid,  if  kept  for  some 
time  at  100°,  any  free  chlorine  possibly  present  may  be  almost  wholly 
expelled.  (Ga^-Lussac.)  Light,  especially  solar  light,  gteailj  accelerates 
the  decomposition.  In  direct  sunshine,  it  takes  place  in  a  few  seconds. 
In  this  decomposition,  chlorine  is  likewise  evolved,  and  the  residue  con- 
tains chloric,  and  sometimes  also  chlorous  acid.  (Balard.)  A  portion  of 
oxygen  is  sometimes  evolved  together  with  the  chlorine,  and  a  small 
quantity  of  hydrochloric  aoid  is  also  formed,  together  with  the  chloric  acid, 
probably  a  secondary  product  resulting  from  the  action  of  the  chlorine  on 
the  water.  (Gbby-Lussao.)  In  the  circuit  of  the  voltaic  battery,  the  aque- 
ous acid  gives  no  gas  at  the  negative  pole,  but  oxygen  at  the  positive  pole, 
pure  at  fibrst,  but  iSterwards  mixed  with  chlorine.  (For  the  other  modes 
of  decomposition  of  the  aqueous  acid,  vid.  pp.  297,  298.) 

6.  With  Salifiable  Bases :  Hypochlorites.  The  aqueous  acid  decom- 
poses the  alkaline  carbonates  with  effervescence.  Preparation.  1.  By 
bringing  aqueous  hypochlorous  acid  in  contaet  with  alkalis,  magnesia, 
hydratod  oxide  of  zinc  or  hydrated  oxide  of  copper,  rise  of  temperature 
being  carefully  avoided,  and  the  acid  not  added  in  excess.  No  other  salts 
of  hydrochlorous  acid  are  known.  Since  the  combination  is  attended  with 
evolution  of  heat,  whereby  the  hypoehlorite  would  be  resolved  into  chlo- 
ride and  ohlorate,  the  acid  must  lie  added  to  the  alkaline  solution  by  small 
portions  at  a  time,  stirring  frequently,  and  keeping  the  liquid  cool  by 
immersing  the  containing  vessel  in  cold  water :  moreover,  the  acid  must 
not  be  added  in  excess,  because  then  the  same  decomposition  would  take 
place.  From  hypochlorite  of  lime  or  banrta  obtained  in  this  manner;  the 
hypochlorites  of  the  soluble  alkalis  and  of  magnesia  may  be  prepared  by 
precipitation  with  a  carbonate  or  a  sulphate.  The  solution  may  be  evapo- 
rated to  dryness  in  vacuo  at  ordinary  temperatures  without  decomposition, 
provided  it  contains  an  excess  of  alkali.  (Balard.) — 2.  Hypochlorites  are 
obtained  mixed  with  chlorides— forming  the  so-called  Vhloridea  of  the 
Alkalis — when  chlorine  gas  (in  the  proportion  of  somewhat  less  than  1 
equivalent)  is  brought  m  contact  with  caustic  fixed  alkalis  (magnesia 
included)  or  their  carbonates,  dissolved  in  or  diffused  through  water,  the 
temperature  being  kept  as  low  as  possible. 

2KO  +  2C1  =  KCI  +  KO,C10. 
If  the  temperature  should  rise  too  high  in  consequence  of  the  absorption^ 


300  CULORINli:. 

oxygen  gajs  will  be  evolved,  and  the  b^rpocblorite  partly  resolved  into 
chloride  and  chlorate.  Excess  of  chlorine  likewise  brings  about  the 
decomposition  of  the  hypochlorite  into  chloride  and  chlorate,  with  evola- 
tion  of  a  quantity  of  oxygen  gas,  amounting  to  between  2  and  3  per  cent, 
of  that  contained  in  the  hypochlorous  acid.  This  decomposition  takes 
place  even  when  the  liquid  is  so  dilute  that  no  chlorate  crystallizes  oat ; 
it  likewise  takes  place  with  lime  and  magnesia.  Hence  only  6  atoms  of 
chlorine  should  be  added  to  7  of  alkali :  in  that  case,  3  atoms  of  chloride 
are  produced,  and  there  remain  3  atoms  of  hypochlorous  acid  with  4  atoms 
of  alkali.  (Gay-Lussac.) 

Chloride  of  lime  having  been  obtained  in  this  manner,  the  correspond- 
ing compounds  of  ammonia,  potash,  or  soda  may  be  obtained  by  precipi- 
tating its  solution  with  the  carbonates  of  these  alkalis.     When  chlorine 
gas  is  passed  through  an  aqueous  solution  of  carbonate  of  potash  pre- 
viously saturated  with  chloride  of  potassium,  a  precipitate  of  chloride  of 
potassium  is  produced — a  proof  that  a  fresh  portion  of  that  salt  is  formed 
by  the  action  of  the  chlorine,  and  consequently  that  the  chlorine  does  not 
combine  directly  with  the  alkali  (Berzelius) :  a  similar  result  is  obtained 
with  solution  of  carbonate  of  soda  saturated  with  common  salt.  (Soubeiran.) 
When  chloride  of  soda  (obtained  by  decomposing  chloride  of  lime  with 
carbonate  of  soda)  is  evaporated  to  dryness  in  vacuo — ^by  which  it  loses 
but  very  little  of  its  bleaching  power — and  the  residue  digested  in  satu- 
rated solution  of  common  salt,  that  liquid  dissolves  the  hypochlorite  of 
soda,  and  leaves  a  quantity  of  common  salt  amounting  to  83  per  cent  of 
the  original  residue.     If  the  evaporation  has  not  been  carried  quite  to 
dryness,  the  cubes  of  common  salt  are  covered  with  a  mother-liquor, 
together  with  effloresced  crystals  of  hypochlorite  of  soda.  (Soubeiran.) 
When  a  mixture  of  chlorine  and  oxygen  gases  (about  2  vols,  chlorine  to  1 
vol.  oxygen)  is  passed  through  an  aqueous  solution  of  an  alkali— potash, 
for  example — the  oxygen  is  absorbed,  and  a  pure  alkaline  hypochlorite  is 
obtained,  not  mixed  with  chloride,  and  consequently  of  double  bleaching 
power.    Common  air  may  be  used  instead  of  oxygen.  (Mackenzie,  Conipt, 
Bend,  6,  865;  also  J,  pr,  Chem.  16,  47.)      Marchand  (J,  pr.  Chem.  16, 
48)  corroborates  this  statement  with  reference  to  lime  also.    On  the  other 
hand,  Otto  {N.  Br,  Arch.  19, 160)  found  that  the  statement  in  question  is 
incorrect,  as  far  as  potash  is  concerned :  the  author  likewise  observed  not 
the  slightest  absorption  of  oxygen  contained  in  a  bottle,  together  with 
solution  of  carbonate  of  soda  into  which  chlorine  gas  was  passed.     When 
chlorine  is  passed  into  aqueous  solution  of  acetate  of  potash,  a  large 
quantity  of  it  is  absorbed,  with  corresponding  disengagement  of  acetic 
acid.     The  product  is  a  strongly  bleaching  yellow  liquid,  which  evolves 
chlorine  when  treated  with  a  stronger  acid;  gives  off  un decomposed  acetic 
acid  together  with  a  small  quantity  of  chlorine,  when  distilled,  while  chlo- 
ride of  potassium,  chlorate  and  acid  acetate  of  potash  remain  behind: 
when  exposed  to  the  air,  it  gradually  gives  up  its  chlorine  and  loses  its 
bleaching  power.  (Liebig.)     Raab  (Bepert  32,  224)  regards  the  chlorides 
of  the  alkalis  as  mixtures  of  metallic  chlorides  with  peroxides  of  the 
metals  and  hydrate  of  chlorine.    Millon  (J,  Fharm,  25,  595 ;  also  J,  pr. 
Chem.  18,  291)  regards  them  as  peroxides  in  which  part  of  the  oxygen  is 
replaced  by  chlorine.  According  to  this  view,  since  peroxide  of  potassium 
is  K0^  chloride  of  potash  must  be  KOCP;  and,  since  peroxide  of  sodium 
is  NaO^  chloride  of  soda  must  be  NaOCl. 

The  hypochlorites  have  a  caustic  and  astringent  taste,  thicken  the 
saliva,  produce  small  white  spots  upon  the  skin,  and  emit  a  peculiar  sickly 


HYPOCHLORITES.  301 

odour  when  they  come  in  contact  with  organic  snbstances.  They  contain 
1  atom  of  base  combined  with  1  atom  of  acid.  (Gay-Lussac.)  1  At.  KO 
dissolved  in  water  and  mixed  with  2  At.  CIO  loses  1  At.  CIO,  when 
placed  in  vacuo  over  hydrate  of  potash  at  ordinary  temperatures :  the 
residue  is  a  mixture  of  chloride  of  potassium  and  chlorate  of  potash. 
(Gay-Lussac.) 

The  aqueous  solutions  of  the  hypochlorites  very  slowly  evolve  oxygen 
gas  when  Kept  in  the  dark  at  ordinary  temperatures.  Such  is  the  case 
with  chloride  of  potash  and  chloride  of  lime,  at  least  according  to  Ber- 
thollet  and  Marin.  Mackenzie,  on  the  other  hand,  maintains  that  the 
alkaline  hypochlorites,  at  ordinary  temperatures,  and  even  near  upon 
100%  absorb  oxygen  and  are  converted  into  chlorates  1 

In  diffused  daylight,  and  more  quickly  in  direct  sunshine  or  by  the 
aid  of  heat,  the  alkaline  hypochlorites  are  resolved — ^generally  with  evo- 
lution of  oxygen  gas — into  a  metallic  chloride  and  a  chlorate,  the  decom- 
position taking  place  with  greater  facility  as  the  alkali  is  less  predomi- 
nant. Mere  evaporation  in  vacuo  induces  this  decomposition,  if  the  alkali 
is  not  in  great  excess.  (Balard.)  When  hypochlorite  of  potash  contain- 
ing 1  atom  of  base  to  1  atom  of  acid  is  kept  for  some  time  at  lOO*',  it 
evolves  13  per  cent  of  the  oxy^n  contained  in  the  acid;  but  if  there  be 
4  atoms  of  base  to  1  atom  of  acid,  the  oxygen  evolved  amounts  to  36  per 
cent. :  with  a  few  exceptions,  the  quantity  of  oxygen  evolved  is  greater, 
the  more  the  alkali  is  in  excess.  Powdered  manganese  added  to  the  solu- 
tion increases  the  Quantity  of  oxygen  evolved,  and  at  the  same  time  com- 
municates a  red  colour  to  the  liquid,  from  formation  of  permanganic  acid. 
The  residue  in  all  cases  contains  chloride  of  potassium  and  chlorate  of 
potash.  Chloride  of  potash  behaves  in  the  same  manner  as  the  pure 
hypochlorite.  (Gay-Lussac.)  Aqueous  chloride  of  potash  evolves  a  por- 
tion of  its  oxygen  when  concentrated  by  boiling,  and  on  passing  to  the 
solid  state  gives  off  a  small  quantity  of  chlorine :  the  solution  and  evapo- 
ration must  however  be  repeated  several  times  before  the  bleaching  com- 
pound is  completely  converted  into  chloride  of  potassium  and  chlorate  of 
potash.  Aqueous  solution  of  chloride  of  potash  evolves  a  small  quantity  of 
chlorine  when  evaporated  in  vacuo.  Solution  of  chloride  of  lime  also, 
when  concentrated  by  boilinK>  deposits  lime,  and  evolves,  first  oxygen,  and 
lastly,  on  passing  to  the  dry  state,  chlorine;  chlorate  of  lime  is  also 
formed.  (Soubeiran.)  Chlorides  of  the  alkalis  containing  excess  of  alkali 
may  be  evaporated  to  dryness  even  at  50°  022''  F.J,  without  being 
resolved  into  chlorate  and  metallic  chloride,  ana  the  residue  still  retains 
considerable  bleaching  power.  (Martens.) 

The  hypochlorites  are  decomposed  at  ordinary  temperatures,  with  loss 
of  bleaching  power,  by  excess  of  hypochlorous  acid,  the  products  being  a 
chlorate  and  a  metallic  chloride.  (Balard.)  This  decomposition  is  pro- 
duced with  even  greater  facility  by  the  addition  of  free  chlorine  to  the 
hypochlorite :  part  of  the  metallic  oxide  is  then  converted  into  chloride- 
while  the  hypochlorous  acid  is  liberated,  and,  at  the  same  time,  a  fresh 
quantity  of  it  is  formed  by  the  combination  of  part  of  the  chlorine  with 
the  oxygen  of  the  metallic  oxide.  (Gay-Lussac.)  Part  of  the  salt  is  pro- 
bably decomposed  in  this  manner : 

KO,  CIO  +  2C1  =  Ka  +  2C10; 
and  the  excess  of  hypochlorous  acid  thus  produced  acts  on  the  rest  of  the 
salt  as  above  descrioed.     The  chlorides  ot  the  alkalis  are  also  completely 
converted  by  excess  of  chlorine  or  hypochlorous  acid,  with  the  aid  of 
heat,  into  chlorate  and  metallic  chloride,  with  evolution  of  chlorine  and  a 


302  CHLORINE. 

small  quantity  of  oxygen.  (Gay-Luflsac.)  Aqueons  solationa  of  the 
alkalis  saturated  with  chlorine  yield  hypochlorous  acid  by  distillation, 
the  residue  containing  metallic  chloride  with  a  trace  of  chlorate.  If 
hydrated  oxide  of  zinc  or  copper  be  saturated  with  chlorine  and  the  liquid 
heated^  a  distillate  of  h3rpoch]orous  acid  is  likewise  obtained.  (Martens; 
vid,  also  Williamson^  Ann,  Pharm.  54,  133.) 

The  aqueous  solutions  of  the  hypochlorites  exert  the  same  kind  of 
oxidizing  action  as  the  solution  of  the  acid  itself,  being  themselves  at  the 
same  time  converted  into  chlorides.  They  convert  phosphorus  or  phos- 
phorous acid  into  phosphoric  acid;  sulphur  or  sulphurous  acid  into  sul- 
phuric acid;  iodine  into  iodic  acid;  nitric  oxide,  absorbing  it  rapidly,  into 
nitric  acid;  arsenic,  which  is  brightened  by  the  action,  into  arsenic  acid; 
iron  rapidly  into  ferric  oxide;  tin  and  copper,  with  evolution  of  a  portion 
of  chlorine  and  oxygen,  into  oxychlorides ;  and  mercury  likewise  into 
oxychlorido :  they  fdso  convert  most  metallic  oxides  of  a  lower  degree 
into  oxides  of  the  highest  degree  of  oxidation,  and  freshly  precipitated 
metallic  sulphides  into  sulphates.  On  the  other  hand,  they  slowly  con- 
vert silver  into  chloride,  with  evolution  of  oxygen.  On  gold  and  platinum 
they  have  no  action.  (Balard.)  The  chlorides  of  the  idkaJis  in  the  state 
of  aqueous  solution  act  in  the  same  manner.  They  convert  phosphorus, 
sulphur,  iodine,  and  arsenic  into  acid, — ^without  evolution  of  chlorine,  if 
the  combustible  body  is  in  excess,  with  evolution  of  chlorine  if  it  is  not — 
because,  in  the  latter  case,  the  acid  formed  by  the  oxygen  derived  from  the 
hypochlorous  acid  combines  with  the  base  and  sets  the  chlorine  ire^ 
They  convert  iron  almost  instantly  into  a  red  powder  consisting  of  ferric 
oxide  free  from  chlorine;  mercury  into  a  grey  pulverulent  oxide  free 
from  chlorine;  and  metallio  sulphides,  such  as  sulphide  of  lead  or  dissolved 
sulphide  of  barium,  into  sulphates.  Antimony,  zinc,  tin,  and  copper,  im- 
mersed in  solution  of  chloride  of  lime,  are  converted  into  oxychlorides, 
the  tin  causing  a  slow,  the  copper  a  quicker  evolution  of  oxygen  gas. 
Finely  divided  silver  immersed  in  chloride  of  lime  is  slowly  converted 
into  chloride  of  silver  with  a  mere  trace  of  oxide,  while  lime  is  set  he^, 
(Soubeiran.) 

The  behaviour  of  hjrpochlorites  with  heavy  metallio  oxides  has  only 
been  examined  with  the  chlorides  of  the  alkalis.  Chloride  of  lime  gives 
with  sulphate  of  manganous  oxide  a  brown-black  precipitate  of  hydrat«d 
peroxide  of  manganese.  (Phillips.)  Chloride  of  lime  in  excess  gives  with 
nitrate  of  lead  a  white  precipitate  of  chloride  of  lead,  which  however 
soon  turns  yellow,  and  afterwards  brown ;  because  the  liquid,  which  con- 
tains hypochlorite  of  lime,  converts  the  chloride  of  lead  into  peroxide, 
with  evolution  of  chlorine.  In  the  first  instance,  CaCI  +  CaO,  CIO  with 
PbO,  NO*  forms  PbCl  -h  OaO,  N0»  +  CaO,  CIO;  subsequently,  CaO,  CIO 
and  PbCl  form  PbO»  +  CaCl  +  CI.  (Balard.)  If  the  nitrate  of  lead  is  in 
excess,  the  white  precipitate  first  produced  is  turned  brown  in  the  same 
manner  by  the  hypochlorite  of  lead  contained  in  the  solution;  and  the 
liquid  when  filtered  from  the  precipitate  becomes  turbid,  and  deposits 
peroxide  of  lead,  with  evolution  of  chlorine.  (Berzelius.) 

PbO,  CIO  =  PbO'  +  CI. 

From  nitrate  of  mercnrous  oxide  chloride  of  lime  precipitates  calomel, 
which  quickly  changes  to  red  oxyohloride;  whereupon,  the  supernatant 
liquid  loses  its  originally  strong  bleaching  power,  and  becomes  rich  in  cor- 
rosive sublimate.  (Balard.)  Chloride  of  lime  so  far  neutralized  Tdih  nitric 
acid  that  it  no  longer  smells  of  chlorine,  gives  with  nitrate  of  sflver  a 


HTPOCHLORITBS.  303 

white  precipitate  of  chloride  of  silver.  The  liquid  filtered  from  this  pre- 
cipitate soon  loses  its  strong  bleaching  power  and  acquires  an  acid  re- 
action, while  chloride  of  silver  is  precipitated  and  chlorate  of  silver  re- 
mains in  solution.  (Berzelius,  Balard.)  Chloride  of  lime  not  neutralized 
hy  nitric  acid  gives  with  small  quantities  of  nitrate  of  silver  a  black  pre- 
cipitate of  peroxide  of  silver ;  the  supernatant  liquid  mixed  with  a  larger 
quantity  of  the  silver-salt  suddenly  evolves  oxygen  gas,  with  violent 
effervescence^  and  loses  its  bleaching  power.  (Berzelius.J  The  black  pre- 
cipitate is  a  mixture  of  chloride  and  oxide  of  silver;  the  liquid,  as  it 
passes  through  the  filter,  effervesces  violently  and  loses  its  bleaching, 
power.  Chloride  of  lime  converts  oxide  of  silver  into  chloride,  with 
violent  evolution  of  oxygen,  derived  partly  from  the  oxide  of  silver, 
jwurtlv  from  the  hypochlorous  acid.  (Balard.) 

The  hypochlorites  destroy  organic  colouring  matters  :  in  other  words, 
they  bleach.     If  the  salt  contains  excess  of  alkali,  no  bleaching  takes 
place  till  an  acid  is  added.     If  to  1  atom  of  potash  dissolved  in  water  and 
turned  blue  by  litmus,  hypochlorous  acid  be  added  in  successive  small 
portions,  no  aecolorization  takes  place  till  about  0*9  At.  acid  has  been 
added ;  but  if  the  potash  is  in  combination  with  carbonic  acid,  the  first 
drops  of  hypochlorous  acid  produce  decolorization.  (Gay-Lussao.)    Car- 
bonate of  potash  mixed  with  a  small  Quantity  of  chlorine  bleaches  litmus; 
caustic  potash  or  lime  similarly  treated  does  not— except  on  the  addition  of 
an  acid ;  e.  g,  on  passing  carbonic  acid  gas  through  the  liquid.  (Gm.)     A 
given  quantity  of  chlorine  will  bleach  the  same  quantity  of  solution  of 
sulnhate  of  indigo,  whether  it  be  combined  with  water  or  with  an  alkaline 
carbonate  (Welter;  Soubeiran);  but  of  colouring  matters  which  do  not 
contain  a  free  acid — ^tincture  of  litmus,  for  example,  the  latter  compound 
bleaches  about  \  less  than  the  aqueous  solution,  and  subsequent  addi- 
tion of  acid  to  the  mixture  produces  no  further  decolorization;  whereas, 
if  the  acid  be  added  to  the  chloride  of  the  alkali  or  to  the  colouring  mat- 
ter, before  the  two  are  mixed,  the  bleaching  action  is  as  strong  as  that 
produced  by  chlorine-water.  (Soubeiran.)     Bibulous  paper  becomes  rotten 
oy  contact  with  salts  of  hypochlorous  acid,  the  action  being  accompanied 
by  rise  of  temperature,  which  gives  rise  to  evolution  of  oxygen  gas  and  a 
small  quantity  of  carbonic  acid,  and  to  the  formation  of  chlorate  and  me- 
tallic cnloride :  if  the  action  takes  place  with  considerable  quantities  of 
material,  the  paper  sometimes  becomes  so  hot  that  it  takes  fire.  (Balard.) 
Nearly  all  acids  decompose  the  hypochlorites,  combining  with  the  base 
and  expelling  the  acid ;  this  effect  is  produced  even  by  a  stream  of  car- 
bonic acid  (reciprocal  affinity"*^).     A  hypochlorite  evaporated  to  dryness 
and  then  treated  with  concentrated  phosphoric  acid  yields  hypochlorous 
acid  gas,  mixed  however  with  a  small  quantity  of  free  chlorine,  because 
a  portion  of  metallic  chloride  is  formed  daring  the  evaporation.  (Balard.) 
Hypochlorites  dissolved  in  water  are  but  partially  deo€mi]>osed  by  carbonic 
acid,  because  the  hypochlorous  acid  remains  dissolved  in  the  liquid :  if 
this  be  distilled  off,  a  fresh  addition  of  carbonio  acid  will  liberate  another 
portion,  and  so  on.  (Gay-Lnssac.)     The  chlorides  of  the  alkalis  mixed 

*  According  to  WiUUmson  (^ii.  Pharm,  54,  133),  bypoehlorow  acid  has  not, 
under  any  circamstances,  the  power  of  expelling  carbonic  add  from  its  combinations, 
unless  it  b  itself  decomposed  at  the  same  time :  so  that,  when  chlorine  is  passed  into 
the  solution  of  an  alkaline  carbonate,  the  hypochlorous  acid  produced  does  not  combine 
with  the  base,  but  remains  free,  and  may  be  c^tained  by  distillation.  On  this  is  founded 
the  mode  of  preparing  the  aqueous  acid  described  on  page  298.  From*  this  it  would  appear 
that  the  reciprocity  of  aflSnities  above  alluded  to  does  not  really  azist*     [W.] 


304  CHLOHINE. 

with  excess  of  sulpburic  acid,  or  any  other  of  the  stronger  acids,  evolve 
nothing  but  chlorine,  because  the  oxygen  of  the  hypochlorous  acid  is  ex- 
pended in  oxidizing  the  metal  of  the  chloride: 

KCl  +  KO,  CIO  +  2S0»  =  2(KO,  S0«)  +  2CI. 
But  if  sulphuric  or  nitric  acid  diluted  with  20  parts  of  water  be  poured 
in  a  very  fine  stream,  with  constant  agitation,  into  solution  of  chloride 
of  potash  or  chloride  of  lime,  and  in  such  quantity  as  barely  to  saturate 
the  alkali  combined  with  the  hypochlorous  acid,  the  metallic  chloride  also 
present  in  the  solution  remains  undecomposed,  and  hypochlorous  acid  is 
obtained  on  distilling  the  liquid.  A  chloride  of  an  alkali  likewise  yields 
hypochlorous  acid  by  distillation  after  chlorine  has  been  added  to  it.  (Gay- 
Lussac). 

I!uMo7^ne.    Protoxide  of  Chlorine. 

A  gas  discovered  by  Sir  Humphry  Davy,  which,  like  hypochlorous 
acid,  contains  1  atom  of  chlorine  to  1  atom  of  oxygen,  but  must  be  re- 
garded, not  as  a  true  chemical  compound  but  as  a  mixture  of  chloric  oxide 
gas  and  free  chlorine.  It  is  evolved  on  carefully  heating  1  part  of  chlorato 
of  potassa  with  2  parts  of  hydrochloric  acid,  and  2  of  water  (or  even  with 
stronger  hydrochloric  acid,  Soubeiran),  and  may  be  purified  from  free 
chlorine  by  agitation  with  mercury.  (H.  Davy.) — This  mode  of  puri- 
fication cannot  be  adopted;  for  the  gas  is  grsMually  but  completely 
absorbed  by  mercury.  (Soubeiran.) 

This  gas  is  of  a  orighter  yellow  than  chlorine,  bleaches  litmus,  smells 
strongly  of  chlorine,  and  at  the  same  time  like  burnt  sugar. 

Euchlorine  explodes  when  heated  (the  heat  of  the  hand  being  some- 
times sufficient  to  produce  violent  explosion) — emitting  a  vivid  light,  and 
often  fracturing  the  containing  vessel :  it  is  well,  therefore,  when  preparing 
it,  to  protect  the  face  by  a  mask.  In  this  manner,  1  volume  of  euchlorine 
is  resolved  into  1  volume  of  chlorine  and  half  a  volume  of  oxygen.  The 
behaviour  of  eachlorine  with  combustible  bodies  is,  for  the  most  part,  the 
same  as  that  of  chloric  oxide  {q.  v.). 

The  discoverer  of  euchlorine  himself  afterwards  admitted  the  correct- 
ness of  regarding  this  gas  as  a  mixture  of  3  measures  of  chlorine  gas 
and  2  measures  of  chloric  oxide.  For  he  found  that,  when  euchlorine 
is  treated  with  water,  a  quantity  of  chlorine  always  remains  unabsorbed, 
and  the  solution  exhibits  the  same  properties  as  water  saturated  with 
chloric  oxide.  This  result  is  still  more  clearly  established  by  the 
experiments  of  Soubeiran,  from  which  it  appears  that  when  water 
is  saturated  with  euchlorine  (in  which  case  chlorine  always  remains 
behind)  and  the  absorbed  gas  driven  out  by  warming  the  liquid;  this 
gas  is  resolved  by  heat  into  about  equal  volumes  of  chlorine  and  oxy- 
gen.* Hence  the  gas  absorbed  by  the  water  contains  only  half  as  much 
chlorine  as  the  original  gas.  Wnen  water  saturated  with  euchlorine  is 
agitated  with  calomel  (Hg^l),  the  calomel  absorbs  the  whole  of  the  free 
chlorine,  forming  corrosive  sublimate  (HgCl);  and  the  gas  subsequently 
evolved  by  the  application  of  heat  exhibits  the  characters  of  chloric 
oxide,  yielding  when  exploded,  1  vol.  chlorine  to  2  vols,  oxygen.     Hence 

*  ConscquenUy,  1  At.  chlorine  to  2  At,  oxygen.  This  componnd,  CIO*,  is  usually 
considered  to  be  wanting  in  the  series  of  oxygen-compounds  of  chlorine:  Berzelius, 
however,  regards  the  experiment  of  Soubeiran  above  described,  as  a  proof,  not  only  of 
its  existence  as  a  distinct  compound,  but  of  its  isolation  baring  been  actually  effected. 
(Traits  de  Chimie,  I.,  558.)  [W.] 


CHLOROUS  ACID.  305 

pnre  chloric  oxide  is  obtained  when  the  gas  evolved  from  chlorate  of  po- 
tassa  by  the  action  of  hydrochloric  acid  is  passed  through  water  surrounded 
with  ice  and  having  calomel  diffused  through  it.  (Soubeiran.) 

The  idea  that  euchlorine  is  a  definite  chemical  compound  rests  only 
on  the  fact  of  its  being  always  constituted  in  the  same  proportions,  and 
always  being  resolved  by  explosion  into  2  volumes  of  chlorine  and  1  of 
oxygen.  Hence^  when  chlorate  of  potash  is  heated  with  hydrochloric 
acid,  the  gaseous  mixture  evolved  must  always  consist  of  3  measures  of 
chlorine  gas  and  2  of  chloric  oxide.  This  may  perhaps  be  explained  as 
follows : — 

;  4(KO,C10*)  +  12HC1  =  4KC1  +  12HO  +  3C10*  +  9CL 

According  to  this  formula,  9  atoms  of  chlorine  are  evolved  for  3  atoms  of 
chloric  oxide,  or  3:1;  and  since  chlorine  is  a  mon-atomic  gas  and  chloric 
oxide  is  di-atomic  (I.,  53,  S6,  67),  this  proportion  gives  3  volumes  of 
chlorine  to  2  volumes  of  chloric  oxide.  ( Vid.  H.  Davy,  Schw.  3,  256. — 
Ann.  Chim,  Phys,  1,  76. — Gay-Lussac,  Ann,  Chim,  Fhys.  8,  410. — 
Soubeiran,  Ann.  Chim.  Phys.  48,  113. — J.  Davy,  N.  Ed,  PhU,  J,  17,  49.) 
Millon  regards  euchlorine  as  a  mixture  of  free  chlorine  with  chloro- 
chloric  acid.  {Vid.  p.  314.) 

IT    B.    Chlorous  Acid.    CIO*. 

Acide  CMoreuXy  Chlorige  Saure. 

Formation. — 1.  By  the  deoxidation  of  chloric  acid.  When  a  mixture 
of  nitric  acid  and  chlorate  of  potash  is  treated  with  various  deoxidizing 
agents  at  a  temperature  below  57°  (135**  F.),  the  chloric  acid  is  deprived 
of  2  atoms  of  oxygen  and  reduced  to  the  state  of  chlorous  acid,  which 
escapes  in  the  form  of  gas.  The  decomposition  of  the  chloric  acid  appears 
to  be  effected  through  the  medium  of  nitrous  acid,  which  is  formed  from 
the  nitric  acid  by  the  action  of  the  deoxidizing  agent. 
N0'  +  C10»=NO*  +  CIO'. 

a.  Perfectly  pure  nitric  acid  of  specific  gravity  1*405  dissolves  chlorate 
of  potash  without  evolution  of  gas,  and  forms  a  colourless  solution,  pro- 
vided the  temperature  be  kept  below  57°;  but  if  the  nitric  acid  contains 
nitrous  acid,  the  addition  of  the  chlorate  of  potash  immediately  pro- 
duces a  yellow  colour,  arising  from  the  formation  of  chlorous  acid. 
The  same  effect  is  produced  if  the  chlorate  of  potash  contains  chlo- 
ride of  potassium,  or  if  the  nitric  acid  is  contaminated  with  hydro- 
chloric acid,  because  in  either  of  these  cases  nitrous  acid  is  formed* 
h.  When  a  stream  of  nitric  oxide  gas  is  passed  into  a  solution  of  chlorate 
of  potash  in  nitric  acid,  at  a  temperature  of  40°  —  45°  (104°—  113*'  F.), 
the  nitric  acid  converts  the  nitric  oxide  into  nitrous  acid  (2N0*  +  NO*  =5 
3N0^),  and  this  compound  converts  the  chloric  acid  into  chlorous  acid. 
Nitric  oxide  alone  has  no  action  either  on  chlorate  of  potash  or  on  free  chlo- 
ric acid. — c.  Most  metals  act  upon  a  mixture  of  nitric  acid  and  chlorate  of 
potash  in  such  a  manner  as  to  form  chlorous  acid  :  the  metal  is  oxidized  at 
the  expense  of  a  portion  of  the  nitric  acid,  and  nitric  oxide  is  produced — and 
this  gives  rise  to  the  action  already  described  in  6.  Zinc  produces  but  a 
leeble  action  in  a  mixture  of  nitric  acid  and  chlorate  of  potash  at  18^ 
64-4°  F.);  but  at  24®  (75-2°  F.)  the  action  is  stronger,  and  chlorous  acid 
is  rapidly  evolyed.  The  vesel  must  be  immersed  in  cold  water  to  prevent 
the  temperature  from  rising  too  high.     If  the  nitric  acid  be  so  dilute  that 

VOL.   II.  X 


806  CHLORINB. 

the  rino,  if  acting  on  it  alone,  would  liberate  nitrons  oxide  inatead  of 
nitric  oxide,  no  chlorons  acid  is  evolred,  but  on] j  nitrons  oxide.  Iron 
behayes  like  zinc,  excepting  that  it  requires  a  temperature  of  40*^  (104'^ 
F.)  to  nmke  it  act;  it  must  be  used  in  rather  thick  pieces.  Lead  is  not 
attacked  till  the  liquid  is  raised  nearly  to  the  temperature  at  which  chlo* 
reus  acid  is  decomposed;  hence  an  irregular,  percussiye  action  takes 
place,  and  free  chlorine  and  oxygen  pass  off,  mixed  with  undecomposed 
chlorous  acid.  Tin  dissolves  completely  without  evolution  of  ^as,  if  the 
temperature  be  kept  low :  this  results  from  the  secondary  action  of  the 
chlorous  acid  on  the  metal.  On  raising  the  temperature  to  40°  —  45^  a 
considerable  quantity  of  chlorous  acid  is  evolved.  Mercury  remiuns  un- 
altered in  nitric  acid,  either  concentrated  or  dilute,  to  which  chlorate  of 
potash  is  added :  the  most  violent  action  between  the  acid  and  the  metal 
IS  instantly  stopped  by  the  addition  of  this  salt.  Similarly,  with  copper, 
silver,  and  bismuth.  Antimony  oxidizes  very  slowly  in  nitric  aoid  to 
which  chlorate  of  potash  is  added.  This  peculiar  check  to  the  oxidating 
action  of  nitric  acid  appears  to  be  connected  with  the  reconversion  of 
nitrous  acid  into  nitric  acid  by  the  action  of  the  chloric  acid.— ^i.  Many 
oxides  and  acids  of  the  lower  degrees  of  oxidation  act  in  the  same  man- 
ner as  the  metals :  arsenious  acid,  for  example,  added  to  a  solution  of 
chlorate  of  potash  in  nitric  acid  causes  an  abundant  evolution  of  chlorous 
acid. — e.  Many  organic  substances,  as  sugar,  gum,  starch,  dextrin,  fibrin, 
albumen,  wood,  charcoal,  muscular  flesh,  animal  membrane,  fat,  oily  acids, 
urea,  citric  acid,  tartaric  aoid,  volatile  oils,  and  resins,  also  evolve  chlorous 
acid  from  a  mixture  of  nitric  acid  and  chlorate  of  potash.  In  all  these 
cases,  it  might  be  supposed  that  the  decomposition  of  the  chloric  acid  is 
produced  by  the  direct  action  of  the  deoxidizing  body — a  metal,  for  ex- 
ample— ^the  nitric  acid  merely  serving  to  liberate  the  chloric  acid  from  its 
combination  with  the  alkali.  But  if  that  were  the  case,  the  same  sub- 
stances ought  to  evolve  chlorous  acid  from  an  aqueous  solution  of  chloric 
acid — which  they  do  not;  neither  is  chlorous  acid  evolved  when  sulphuric 
or  hydrochloric  acid  is  substituted  for  the  nitric  acid.  The  reduction  of 
nitric  acid  to  nitrous  acid  and  its  reoxidation  by  chloric  acid  appears  to  be 
essential  to  the  process. 

2.  By  the  decomposition  of  hypochloric  acid.  {Vid.  p.  296.) 

PreparcOion,—!.  A  flask  of  the  capacity  of  300 — 400  cubic  centime- 
tres (about  20  cubic  inches)  is  filled  almost  to  the  neck  with  a  mixture  of 
1  part  tartaric  acid,  2  of  chlorate  of  potash,  6  of  ordinary  nitric  of  sp.  gr. 
1-327,  and  8  of  water.  The  tartaric  acid  and  chlorate  of  potash  are  first 
introduced,  having  been  previously  mixed  but  not  pounded,  and  then  the 
mixture  of  the  acid  and  water.  The  action  begins  spontaneously  after  a  few 
minutes  at  a  temperature  of  25°  (77*  F.);  it  ma^,  however,  be  accelerated 
without  risk  of  explosion  by  the  application  of  a  very  gentle  heat,  as  by 
placing  a  single  glowing  coal  under  the  flask ;  the  temperature  should 
never  exceed  45°  or  50°  (113  —  122*  P.).  The  gas,  after  being  dried  by 
passing  over  chloride  of  calcium,  may  be  collected  by  displacement  in  dry 
Dottles;  or  if  an  aqueous  solution  be  required,  the  gas  may  be  passed  into 
a  series  of  Woulfe's  bottles  containing  water.  The  action  is  at  an  end 
when  the  mixture  in  the  flask  becomes  colourless.  The  chlorous  acid  thus 
obtained  is  mixed  with  carbonic  acid  resulting  from  the  oxidation  of  the 
tartaric  acid;  but  it  is  sufllciently  pure  for  nearly  all  experiments  that 
can  be  made  with  gas;  and  the  process  is  much  easier  and  attended  with 
less  danger  than  any  other  mode  of  preparing  the  same  compound.   Slight 


CHLOROUS  ACID.  807 

percuBsions  sometimes  take  place  in  the  apparatus,  bnt  thej  nerer  amount 
to  dangerous  explosions. — 2.  To  obtain  chlorous  acid  free  from  carbonic 
acid,  arsenions  acid  maj  be  substituted  for  the  tartaric  acid.  Three  parts 
of  arsenious  acid  and  4  of  chlorate  of  potash  finely  pounded  and  mixed 
with  water  to  a  fluid  mass,  are  put  into  a  flask  like  that  used  in  the  first 
method,  and  the  flask  filled  up  to  the  neck  with  a  mixture  of  12  parts 
nitric  acid  and  4  parts  water :  the  mixture  is  then  gentlj  heated.  The 
nitric  acid  must  be  pure  and  free  from  all  admixture  of  hydrochloric  or 
sulphuric  acid ;  as  either  of  these  acids  would  cause  the  eyolution  of  hj* 
pochloric  acid  and  give  rise  to  yiolent  explosions.  If  these  impurities  are 
present  in  the  nitric  acid,  the  flask  containing  the  mixture  must  be  im- 
mersed in  cold  water  for  several  hours,  before  being  heated  to  liberate  the 
chlorous  acid. — 3.  By  decomposing  a  salt  of  chlorous  acid  by  means  of  a 
stronger  acid.  The  most  convenient  salt  for  this  purpose  is  the  chlorite 
of  lead.  To  obtain  this  salt,  an  aqueous  solution  of  chlorous  acid  is  satu- 
rated with  baryta-water,  the  solution  separated  by  filtration  from  carbo* 
nate  of  baryta  (if  any),  and  mixed  with  a  perfectly  neutral  solution  of  nitrate 
of  lead.  Chlorite  of  lead  is  then  precipitated  in  beautiful  sulphur-yellow 
laminsd,  which  may  be  collected  on  a  filter  and  washed.  To  obtain  the 
acid  from  this  salt,  it  is  mixed  to  a  pasty  consistence  with  sulphuric  acid 
diluted  with  an  equal  bulk  of  water,  the  mixture  introduced  into  a  small 
flask,  and  heated  to  a  temperature  between  40°  and  50^  degrees,  fresh  acid 
being  added  when  necessary  by  means  of  a  safety-tube.  The  ana  is 
evolved  with  great  facility,  nothing  being  left  in  the  flask  but  sulphate 
of  lead  and  a  small  quantity  of  chlorous  acid,  which  is  retained  in 
combination  with  the  sulphuric  acid,  and  cannot  be  expelled  without 
the  application  of  a  degree  of  heat  which  would  give  rise  to  explosive  de* 
composition.  This  is  the  only  mode  of  obtaining  chlorous  acid  perfectly 
pure ;  that  which  is  produced  by  the  second  process  always  contains  a 
small  quantity  of  hypochloric  acid.  Whatever  may  be  the  process 
adapted  for  the  preparation  of  chlorous  acid,  it  is  advisable  to  guard 
against  accidents  by  surrounding  the  apparatus  with  a  cage  of  wiie-gauie 
or  a  cloth. 

Propei*ties,  Chlorous  acid  is  a  gas  of  a  rather  dark  greenish-yellow 
colour  and  strong  pungent  odour,  irritating  the  air-passages  like  hypo- 
chloric  acid.  It  oleaches  litmus-paper  and  solution  of  indieo.  Does  not 
liquefy  when  cooled  by  a  mixture  of  ice  and  salt.  ^Millon!)  Condenses 
to  a  reddish  liquid  when  exposed  to  intense  cohl.  (Berzelius.)  Specific 
gravity  of  the  gas  =  2*646.  (Millon.) 

Calcnlatioii.  Millon.  VoL      8p.gr.    Vol.       8p.gr« 

a 35-4  ....  69-60  ....  6015         Chlorine  gas 2  ....  49086    =  I  ....  16362 

30   ....240  ....  40-40  ....  39*85         Oxygen  gaa 3  ....  3-3276    =  1  ....  llOQg 

aO«....59-4  ....100-00  ....10000     ChlorooB  add  gas....  3  ....  82362    »1  ....  2*7454 
(C1«0»  «  2  .  221*83  +  3  .  100=  74266.    BeneUna.) 


Decompositions. — 1.  The  gas,  when  heated  to  57®  (135**  F.),  explodes 
with  moderate  force,  and  is  resolved  into  chlorine  and  oxygen.  It  ex- 
plodes when  brought  in  contact  with  most  combustible  bodies,  as  with 
sulphur,  selenium,  tellurium,  phosphorus,  and  arsenic.  Iodine  absorbs 
it,  forming  a  mixture  of  chloride  of  iodine  and  iodic  acid.  Bromine 
exerts  noaction  upon  it.  Many  metals,  e.g,  copper,  lead,  tin,  antimony, 
silver,  and  iron -filings  may  bo  left  for  hours  in  tne  gas  without  producing 

X  2 


308  CHLORINE. 

any  effect;  but  mercury  absorbs  it  completely.  Caustic  baiyta  and  lime 
absorb  the  gas  very  slowly.  Oxide  of  silver  decomposes  it  instantly  ; 
the  oxides  of  lead  and  copper  and  di-oxide  of  mercury^  more  slowly. 

Combinations,  a.  With  Water.  Aqueous  Chlorous  acid.  Water  at 
ordinary  temperatures  absorbs  about  5  or  6  times  its  volume  of  chlorous 
acid  gas.  The  solution  is  green  when  it  contains  but  little  of  the  gas  ; 
deep  golden  yellow  when  saturated.  A  few  bubbles  of  the  gas  are  eufii- 
cient  to  give  a  perceptible  colour  to  a  pint  of  water — ^a  tinting  power 
which  can  only  be  compared  to  that  of  the  soluble  salts  of  chromic  acid. 
-The  saturated  solution  has  a  caustic  taste>  and  at  20^  produces  a  yellow 
stain  on  the  skin  when  placed  in  contact  with  it  for  a  few  seconds.  The 
solution,  like  the  gas,  bleaches  litmus  and  sulphate  of  indigo,  just  as 
chlorine  and  hypochlorous  acid  do  ;  but  the  bleaching  action  of  chlorous 
acid  is  not  diminished  by  the  addition  of  arsenious  acid ;  whereas  that  of 
chlorine  and  hjrpochlorous  acid  is  completely  destroyed  by  it.  If  a  few 
drops  of  a  weak  solution  of  chlorous  acid  {e.  g.  a  solution  containing  its 
own  volume  of  water)  be  dropped  into  a  bottle  containing  air  saturated 
with  moisture,  a  thick  white  cloud  rises  from  the  bottom  of  the  bottle, 
fills  it,  and  continues  to  flow  out  at  the  mouth  for  upwards  of  half  an 
hour.     [For  the  cause  of  this  phenomenon,  vid.  p.  318.] 

2.  The  aqueous  solution  of  chlorous  acid  converts  mercury  into  oxy- 
chloride,  and  copper  into  chlorate  and  chloride ;  with  zinc  and  lead,  chlo- 
ride and  chlorite  are  at  first  produced ;  but,  if  the  acid  is  in  excess,  the 
ultimate  products  are  chloride  and  chlorate.  On  gold,  platinum,  and 
antimony,  it  exerts  no  action.  The  salts  of  the  alkalis  and  earths  in  the 
state  of  aqueous  solution  are  not  altered  by  it;  neither  does  it  exert  any 
action  on  the  salts  of  zinc  or  on  the  dichloride  or  protochloride  of  mercury. 
Protochloride  of  tin  it  converts  into  bichloride.  Mixed  with  solution  of 
nitrate  of  manganous  oxide,  or  of  protochloride  of  manganese,  it  converts 
the  metal  into  peroxide;  similarly,  with  acetate  of  lead.  With  solution 
of  subacetate  of  lead  also  it  gives  an  immediate  precipitate  of  peroxide. 
Ferrous  salta  are  auickly  converted  by  it  into  ferric  salts.  Nitrate,  ace- 
tate, sulphate,  ana  chloride  of  copper  assume  a  green  colour  when  mixed 
with  it,  but  undergo  no  definite  change.  Salts  of  gold  and  platinum  are 
not  affected  by  it. 

b.  With  Chloric  acid.  c.  With  Perchloric  acid. 
d.  With  Salifiable  Bases.  Chlorites,  The  chlorites  of  potassti,  soda^ 
baryta,  and  strontia,  which  are  soluble,  are  formed  by  mixing  the  aque- 
ous acid  with  the  solutions  of  these  alkalis.  Combination  does  not  take 
place  immediately,  on  account  of  the  feebleness  of  the  affinity  of  chlorous 
acid  for  salifiable  bases ;  at  least  an  hour  elapses  before  the  odour  of  the 
acid  is  quite  destroyed.  The  carbonates  of  potassa,  soda,  baryta,  strontia, 
and  lime,  are  not  decomposed  by  chlorous  acid.  From  the  solutions  of  the 
alkaline  chlorites,  the  lead  and  silver-salts,  which  are  insoluble  in  water, 
may  be  obtained  by  double  decomposition :  the  same  method  will  doubt- 
less be  found  applicable  to  the  preparation  of  other  insoluble  chlorites. 
The  normal  salts  of  chlorous  acid  contain  1  atom  of  acid  to  1  atom  of 
base :  those  which  are  soluble  arc  colourless,  and  taste  like  the  acid  itself; 
they  likewise  destroy  vegetable  colours.  With  potassa,  soda,  and  baryta^ 
chlorous  acid  also  forms  acid  salts,  which  are  red  when  in  solution,  but 
cannot  be  obtained  in  the  solid  state.  Chlorous  acid  also  forms  basic  salts 
which  contain  2  atoms  of  base  to  1  of  acid.  The  chlorites  are  distin- 
guished from  the  hypochlorites  by  the  fact  that  their  bleaching  power  is 


IIYPOCHLORIC  ACID.  309. 

not  destroyed  by  a  solation  of  arson ious  acid  in  nitric  acid.  Chlorous 
acid  is  completely  expelled  from  its  combinations  by  carbonic  acid,  pro- 
vided it  is  free  to  escape,  and  fresh  quantities  of  carbonic  acid  are  conti- 
nually added :  hence  the  chlorites  are  decomposed  by  exposure  to  the 
air.  The  chlorites  of  baryta,  strontia,  lead,  and  silver,  are  crystallizable. 
(Vid.  Millon,  Ann.  Pkarm.  46, 298;  also  Berzelius,  TraiUy  L,  553.)  IT 


C.    Hyfochlobic  Acid  or  Chloric  Oxide.    CIO*. 

Oxide  of  Chlorine,  Peroxide  of  Chlorine,  Stadion's  Teroxygenated  ChLo- 
rinty  Unterchlors&ure,  Chhrige  Sdure,  Acide  Chloreux,  Devioxide  de 
Chlore; — Chloric  Oxide  gas,  Chloroxydgasy  Gas  deutoxide  de  Chlore. 

Preparation, — 1.  In  the  gaseous  state,  a.  Stadion  fuses  1  part  of 
chlorate  of  potash  iu  a  small  ^lass  retort  till  it  is  reduced  to  a  coherent 
mass — ^pours  upon  it,  when  cold,  4  parts  of  oil  of  vitriol — and  heats  it 
gradually  in  a  water-bath,  raising  the  temperature,  in  the  course  of  three 
hours,  from  12*"  to  100^ 

3(KO,  CJO»)  +  4S0*  =  2(K0,  2SO^)  +  KO,  CIC  +  2C104. 

6.  Davy  mixes  30  grains  of  finely  pounded  chlorate  of  potash  with  a 
small  quantity  of  oil  of  vitriol  to  the  consistence  of  a  paste,  puts  the  mix- 
ture into  a  retort,  and  heats  it  gradually  in  a  water-bath  to  which  a  little 
alchohol  has  been  added  to  keep  the  temperature  below  100". — c,  Gav- 
Lussac  makes  the  paste  with  oil  of  vitriol  diluted  with  one-half  water.  The 
first  portions  of  chloric  oxide  which  come  in  contact  with  the  oil  of  vitriol 
and  turn  it  brown,  are  evolved  as  soon  as  beat  is  applied  ;  but  if  the  heat 
becomes  too  strong  and  afi*ects  the  gas  itself  more  than  the  materials  in 
the  retort,  explosion  takes  place ;  hence  it  is  necessary  to  protect  the  face 
with  a  mask.  The  gas  is  collected  over  mercury ;  but  the  mercury  is 
thereby  partly  converted  into  calomel;  for  the  gas  is  always,  especially 
towards  the  end  of  the  operation,  mixed  with  free  chlorine  and  oxygen. 
(Stadion.)  The  gas-delivery  tube  should  be  surrounded  with  paper  kept 
moist  by  a  stream  of  cold  water,  to  guard  against  explosion.  Stadion*s 
method  with  excess  of  oil  of  vitriol  is  the  safest ;  but  the  gas  which  it 
yields  always  contains  free  oxygen,  which  remains  behind  when  the 
chloric  oxide  is  absorbed  by  water  or  mercury  (and  strongly  cooled). 
Soubeiran.  %  Millon  adds  finely-pounded  chlorate  of  potassa  by  small 
portions  at  a  time  to  sulphuric  acid  previously  cooled  by  a  mixture  of  ice 
and  salt,  stirring  with  a  glass  rod  after  each  addition*.  When  a  suificient 
quantity  has  been  added  to  render  the  acid  somewhat  viscid — about  15 
or  20  parts  of  salt  to  1 00  of  acid — ^the  liquid  is  poured  through  a  funnel 
into  a  flask,  care  being  taken  not  to  soil  the  neck  of  the  flask  at  the  part 
which  is  touched  by  the  cork,  as  otherwise  explosion  will  very  pro* 
bably  ensue.  A  larger  proportion  of  oil  of  vitriol  would  decompose  nearly 
all  the  chloric  acid  into  chlorine  and  oxygen  ;  and  if  a  larger  proportion 
of  the  chlorate  were  used,  a  violent  explosion  would  probably  take  place 
soon  after  the  mixture  was  put  into  the  vessel.     The  flask  is  heated  in  a 

*  The  purer  the  chlorate  of  potassa,  the  less  dftnger  is  there  of  explosion.  The  ten- 
dency to  violent  explosions  is  much  increased  by  the  presence  of  mechanically-combined 
water,  or  of  chloride  of  potassium.  If  any  considerable  quantity,  as  500  or  600  grains, 
of  the  chlorate  is  to  be  used,  the  precaution  of  cooling  the  oil  of  vitriol  is  absolutely  ne* 
cessary,  especially  if  the  saltbe  impure.  (Millon.) 


SIO  CHLORINE. 

water-bath,  wbich  must  be  alowly  raised^  by  means  of  a  single  glowing 
coal  plaoed  under  it,  to  a  temperature  not  exceeding  20°  (68  F°) :  at  a 
later  stage  of  the  operation  the  beat  may  be  graduailj  raised  to  between 
80"*  and  60**  (Ha"" — 104^  F.):  this  rise  oi  temperature  makes  no  alteration 
in  the  composition  of  the  gas  evolved.  The  gas,  which  is  heavj,  may  be 
collected  in  small  bottles,  by  displacement ;  mercury  absorbs  it  raUier 
quickly.  For  safety,  the  apparatus  should  be  surrounded  with  wire- 
gauze  or  with  a  linen  cloth.  The  gas  obtained  by  this  method  is  purer 
than  that  which  is  yielded  by  either  of  the  preceding,  but  still  contains 
free  chlorine  and  oxygen.  The  only  way  of  obtaining  the  compound 
quite  pure  is  to  liquefy  it  by  cooling.  (MiUon.) 

2.  In  the  liquid  state.  (I.,  286.)  Oil  of  vitriol  is  put  into  the  shorter 
arm  of  the  tube  and  chlorate  of  potassa  into  the  longer  arm — the  latter  is 
sealed — ^the  oil  of  vitriol  made  to  flow  into  it,  and  the  whole  left  to  itself 
for  24  hours.  The  longer  arm  is  then  heated  to  38""  (lOO""  F.)  and  the 
shorter  arm  cooled  to  — 18°  (0'  F.)  {Faraday;  Comp.  Niemann,  I.,  287.) 
IT  A  much  simpler  mode  of  obtaining  the  liquid  acid  is  to  pass  the  gas, 
as  it  is  evolved  from  a  mixture  of  chlorate  of  potassa  and  sulphuric  acid, 
into  a  tube  sealed  at  one  end  and  surrounded  with  a  mixture  of  ice  and 
salt.  The  tube  should  be  changed  at  least  every  hour,  as  the  liquid  ex- 
plodes with  as  much  violence  as  chloride  of  nitrogen.  (Millon.)  IT 

Properties.  The  liquid  oxide  for  acid)  is  very  fluid,  of  a  deep  yellow 
colour,  and  transparent :  on  openmg  the  tube,  it  evaporates  with  great 
force.  (Faraday.)     Greenish  yellow,  and  of  specific  gravity  about  V5, 

i Niemann.)  Red,  like  bright-coloured  chloride  of  sulphur;  boils  at  20^ 
Millon.)  For  the  tension  and  density  of  the  gas,  vu?.  I.,  261,  279.  The 
sas  has  a  brighter  yellow  colour  than  chlorine.  It  does  not  bleach  dry 
litmns  paper,  but  destroys  the  colour  of  that  which  is  moistened,  without 
previously  reddening  it  (Stadion ;  H.  Davy):  according  to  Berzelius,  it 
first  reddens  litmus,  and  then  bleaches  it.  Its  odour  is  not  so  suffocating 
as  that  of  chlorine  (Stadion):  it  has  an  aromatic  odour  like  that  of  burnt 
sugar,  without  any  accompanying  smell  of  chlorine.  (H.  Davy.) 


Calculation. 

a 35-4  

40 320  

..  52-5 
..  47-5 

Chlorine  gas 
Oxygen  gaa 

Vol. 

....  i  

....  1  

Sp.gr. 
...  1-2272 
...  11093 

CIO*  ....  67-4  

...1000 

1  

...  2-3365 

This  is  the  composition  of  chloric  oxide,  according  to  Davy,  Oay- 
Lussac,  Soubeiran,  and  Millon :  Stadion,  on  the  contrary,  regards  it  as 
a  compound  of  1  At.  chlorine  and  3  At.  oxygen,  or  of  2  volumes  of  chlo- 
rine and  3  of  oxygen  condensed  into  3  volumes. 

Decomposiiions. — 1.  The  eas  remains  unaltered  in  the  dark;  but  in 
sun-light,  it  is  gradually  resolved  into  its  elements.  Sudden  heating  to 
100^  the  passage  of  an  electric  spark,  or  even  agitation  with  mercury, 
produces  an  instantaneous  decomposition,  attended  with  vivid  light  and 
powerful  detonation,  and  often  with  fracture  of  the  containing  vessel. 
Two  measures  of  chloric  oxide  are  thus  resolved  into  1  measure  of  chlo- 
rine and  2  of  oxygen.  (H.  Davy;  Gay-Lussac;  Soubeiran.)  According  to 
Stadion,  3  vols,  chloric  oxide  yield  2  vols,  chlorine  and  3  vols,  oxygen. — 
2.  A  mixture  of  3  measures  of  chloric  oxide  gas  and  about  8  measures 
of  hydrogen  explodes  by  the  electric  spark,  producing  water  and  hydro- 
chloric a«id.  (Stadion.)    Spongy  platinum  induces  tUs  decomposition  at 


HYPOCHLOMC  ACID.  311 

ordinary  temporatares.  (Blundell,  Pogg.  2,  216).— 3.  With  ammoniaoal 
gas,  it  snfiers  decomposition  at  ordinary  temperatures.  (Stadion.)-— 4.  The 
gas  explodes  violently  by  contact  with  phosphorus  (Stadion,  H.  Davy), 
and  also  with  sulphur  (Stadion)  at  ordinary  temperatures. — 5.  Mercury 
absorbs  the  gas  slowly,  being  itself  converted  into  chloride  of  mercury 
and  chlorate  of  mercurous  oxide.  (Stadion.)  Nothing  is  left  behind  but 
the  free  oxygen  previously  mixed  with  the  gas. 

Comhifuxtions.  a.  With  Water.  IT  m.  Hydrcnte  of  Hypoehlorio  acid. 
When  water  at  0®  is  poured  upon  the  liquid  acid,  a  solid  yellow  hydrate 
is  formed,  which  cannot  be  liquefied  without  the  loss  of  a  great  quantity 
of  gas.  The  gas  which  escapes  is  undecomposed  chloric  oxide,  but  the 
last  portions  are  retained  by  the  water  with  great  obstinacy,  so  that 
complete  decomposition  of  the  hydrate  can  only  be  effected  by  elevation 
of  temperature  or  by  passing  a  stream  of  another  gas  through  the  liquid. 
(Millon.)  IT 

/3.  Aqueoiu  Chloric  oxide  or  Aqueous  Hypochloric  acid.  Water  absorbfl 
more  than  7  times  Its  volume  of  chloric  oxide  gas  (Stadion);  more  than 
20  times  its  volume  at  4^.  (Millon.)  The  solution  is  of  a  deep  yellow 
colour,  tastes  rough  and  caustic,  but  not  acid;  emits  white  fumes  on  ex- 
posure to  the  air,  precipitates  nitrate  of  silver  in  proportion  as  it  under^ 
goes  decomposition ;  has  the  same  odour  and  the  same  effect  on  litmus  as 
the  gas.  In  the  dark  it  remains  undecomposed ;  but  when  exposed  to 
diffused  daylight,  it  undergoes  decomposition  in  the  course  of  a  few 
months,  and  by  exposure  to  direct  sunshine,  in  a  few  hours :  the  products 
of  the  decomposition  are  chloric  acid  and  free  chlorine.  (Stadion.)  The 
su^rior  affinity  of  water  for  chloric  acid  causes  the  oxygen  of  the  chloric 
oxide  to  combine  with  a  portion  only  of  its  chlorine  (5C10*= 4010*4- 
01).  When  the  solution  is  heated  in  the  dark,  the  gas  escapes  without 
leaving  an  acid  in  the  liquid.  (Soubeiran.) 

6.  iViih  Salifiable  Bases.  Mypochloratea?.  According  to  Stadion  and 
Sir  H.  Davy,  chloric  oxide  gas,  when  passed  through  aqueous  solutions  of 
the  alkalis,  is  immediately  resolved  into  chloric  acid  and  chlorine,  so  that 
a  chlorate  of  the  alkali  and  a  chloride  of  the  metal  are  produced : 

6K0  +  6C10*  =  6(K0,C10»)  +  KCl, 

On  the  other  hand,  it  appears  from  the  experiments  of  Martens  (Ann* 
Chim,  Fkys.  61,  293;  also  /.  pr.  Ohem.  8,  264)  that  there  really  exist 
definite  salts  of  hypochloric  acid,  which  are  resolved  under  the  same  cir- 
cumstances as  the  hypochlorites,  only  not  so  easily,  into  chlorate  and 
metallic  chloride.  When  chloric  oxide  gas  is  passed  into  a  solution  of 
potassa,  soda,  or  baryta,  or  into  milk  of  lime,  and  in  such  quantity  that 
the  liquid  still  remains  alkaline,  a  colourless  solution  is  obtained  which 
does  not  bleach  litmus  till  an  acid  is  added  to  it— does  not  contain  a  salt 
of  chloric  acid,  except  when  highly  concentrated, — ^and  may  be  ©Vfipo- 
rated,  at  a  gentle  heat,  or  better  in  vacuo,  to  a  dry  crystalline  mass.  Thd 
liquid  when  heated  with  dilute  mineral  acids,  or  with  the  stronger  vege- 
table acids,  evolves  chloric  oxide  gas,  with  brisk  effervescence;  whereas 
a  mixture  of  chlorate  and  chloride  similarly  treated  does  not  evolve  a 
perceptible  (quantity  of  chloric  oxide  gas.  When  an  alkaline  solution  is 
saturated  with  chloric  oxide,  a  strongly  bleaching  liquid  is  produced 
which  is  no  longer  alkaline  (any  excess  of  chloric  oxide,  by  which  the 
solution  is  coloured  brownish-yellow,  escapes  on  exposure  to  the  air^. 
When  this  liquid  is  kept  for  some  time  at  a  temperature  ©f  30*  (176°  F.), 


312  CHIX)RINE« 

or  evaporated  in  racno  at  ordinary  temperatares,  the  salt  vhich  it  con- 
tains is  resolved  into  chlorate  and  metallic  chloride.  Even  carbonic  acid 
passed  through  the  liquid  colours  it  jellow,  and  liberates  a  small  quantity 
of  chloric  oxide ;  stronger  acids  decompose  the  salt  completely,  with  brisk 
effervescence.  Even  when  the  hypochlorate  is  mixed  with  metallic  chlo- 
ride, it  yields,  when  treated  with  acids,  not  chlorine  but  chloric  oxide 
gas.  (Martens.)  H  Millon,  in  repeating  the  experiments  of  Martens,  did 
not  succeed  in  obtaining  definite  silts  of  hypochloric  acid.  To  avoid  rise 
of  temperature  and  consequent  decomposition,  he  made  use  of  the  liquid 
acid,  adding  it  drop  by  drop  to  a  solution  of  potassa;  but  he  found  that 
dilorate  of  potassa  was  always  produced,  however  slowly  the  process  was 
conducted.  The  solution  however  was  not  found  to  contain  any  metallic 
chloride ;  for,  on  the  addition  of  nitrate  of  silver,  it  gave  a  yellow  pre- 
cipitate, which  effervesced  with  nitric  acid,  and  dissolved  completely  in 
boiling  water,  separating  in  yellow  shining  scales  as  the  liquid  cooled. 
The  precipitate  thus  formed  was  chlorite  of  silver,  AgO,  CIO'.  From 
this  it  appears  that  when  hypochloric  acid  is  added  to  an  alkaline  solution, 
even  in  such  a  manner  as  not  to  occasion  rise  of  temperature,  it  is  resolved 
into  chloric  and  chlorous  acids : 

2C104  +  2KO  =  KO,C10*  +  KO,  ClO». 

This  decomposition  is  analogous  to  that  which  frequently  takes  place 
with  hyponitric  acid.  (Millon.)  IF 


D.    Chloric  Acid.    CIO*. 

Hyper-oxymuriatic  acidy  Chloraaure,  Acide  Moriquey  Acide  muriatique 
suroxyffhie,  Acidum  ckloricum. 

Formation,  1.  By  exposing  an  aqueous  solution  of  chloric  oxide  to 
the  light.  2.  By  bringing  chlorine  in  contact  with  water  and  a  fixed 
alkali.     (Scheme  34)  : 

6KO  +  6C1  =  5KC1,K0,C10*; 
or  Scheme  33:  6KO  +6C1  +  5HO  =  5K0,  HCl  +  KO,C10». 

A  mixture  of  metallic  chloride  and  alkaline  hypochlorite  is  always 
produced  at  first  (p.  299);  but  the  latter  is  resolved,  especially  by  tbe 
action  of  light  or  heat  and  excess  of  chlorine,  into  metallic  chloride  and 
alkaline  chlorate  (p.  300).  The  earlier  supposition  of  Berthollet,  Robi- 
quet,  and  others,  that  when  the  solution  is  largely  diluted,  a  chloride  of 
the  alkali  (that  is,  a  mixture  of  metallic  chloride  and  hypochlorite)  is  the 
principal  product — and  that  when  it  is  more  concentrated,  in  which  case 
the  chlorate  crystallizes  out,  the  chief  product  is  a  salt  of  chloric  acid — has 
not  been  confirmed;  since,  according  to  Gay-Lussac,  a  chlorate  is  formed 
by  the  action  of  heat  and  excess  of  chlorine,  even  when  the  liquid  is  very 
dilute. 

Chloric  acid  is  not  known  in  the  separate  state. 

Calculation.  Gay-Lussac.     Chenevix.     VauqaellD.  Volume. 

01 ....  35-4  46-95  46*8  45-  35-     Chlorine  gas  ....      1 

50....  40-0  5305  53*2  55*  65'     Oxygen  gas  ....  2*5 

CIO*    .  75-4  10000  1000  100    100 

(a«0*  =  2  .  221-33  +  5  .  100  =  942-66.    BerzeUus.) 

Combinations,    a.  With  Water.     Aqueow  Cliloric  acid,    Prepara- 


CHLORIC  ACID.  313 

Hon, — 1.  An  aqueous  solution  of  chloric  oxide  is  exposed  to  the  sun's 
rays  till  the.  liquid  becomes  colourless,  and  tlie  free  chlorine  afterwards 
expelled  by  gently  heating  it  in  the  air.  (Stadion;  Gmelin.) — 2.  Chlorate 
of  baryta  is  dissolved  in  water,  and  decomposed  by  dilute  sulphuric  acid. 
The  acid  liquid  above  the  precipitated  sulphate  of  baryta  is  separated 
by  decantation ;  it  should  not  be  rendered  turbid  either  by  sulphuric  acid 
or  by  chlorate  of  baryta.  (Gay-Lussao.) — 3.  A  hot  aqueous  solution  of 
chlorate  of  potassa  is  mixed  with  an  excess  of  hydrofluosilicic  acid,  and 
the  acid  liquid  filtered,  when  cold,  from  the  double  fluoride  of  silicium 
and  potassium ;  it  is  then  evaporated  at  a  temperature  below  30°,  and 
after  a  couple  of  days  filtered  through  powdered  glass.  (Serullas.)  Or 
the  acid  liquid  mixed  with  finely-divided  silica  is  left  to  evaporate,  at  a 
temperature  below  30°  (86°  F.)  in  the  air — or  better  in  vacuo,  over  oil 
of  vitriol  or  hydrate  of  potash — whereupon,  the  excess  of  hydrofluoric 
acid  takes  up  a  portion  of  the  silica,  and  forms  gaseous  fluoride  of 
silicium,  which  escapes :  the  chloric  acid  is  then  filtered  from  the  remain- 
ing silica,  and  the  residue  washed  with  water,  that  nothing  may  be  lost. 
(Berzelins.) 

IT  Bottger  decomposes  chlorate  of  soda  by  means  of  oxalic  acid :  7 
parts  of  crystallized  carbonate  of  soda  and  7^  parts  of  tartaric  acid  are 
dissolved  in  24  parts  of  boiling  water;  and  to  this  is  added  a  solution  of  6 
parts  of  chlorate  of  potash  in  1 6  parts  of  water,  likewise  at  a  boiling 
heat,  the  whole  being  well  stirred.  As  soon  as  the  liquids  are  well 
mixed,  the  whole  is  removed  from  the  fire  and  left  to  cool,  so  that  the 
bitartrate  of  potash  produced  may  settle  to  the  bottom.  The  liquid  is 
then  passed  through  a  double  filter,  the  filtrate  mixed  with  a  saturated 
solution  of  oxalic  acid  (6  oxalic  acid  to  18  water)  at  a  temperature  not 
exceeding  56°  ^133°  F.) — the  whole  briskly  stirred — the  vessel  immersed 
in  a  freezing-mixture  made  of  common  hydrochloric  acid  and  crystallized 
sulphate  of  soda,  in  order  to  facilitate  the  separation  of  the  oxalate  of 
soda,  which  is  but  slightly  soluble,  especially  at  low  temperatures;  and 
the  liquid  filtered  again,  to  remove  the  oxalate  of  soda.  The  solution  of 
chloric  acid  thus  obtained  is  not  absolutely  pure,  but  sufficiently  so  for 
technical  applications,  such  as  the  preparation  of  chlorate  of  baryta  for 
pyrotechnic  purposes.  To  obtain  a  pure  and  more  concentrated  acid,  the 
liquid  obtained  by  the  preceding  process  may  be  saturated  with  freshly 
precipitated  carbonate  of  baryta,  the  solution  concentrated  and  left  to 
crystallize,  the  crystals  dissolved  in  a  small  quantity  of  water,  and  the 
baryta  precipitated  by  sulphuric  acid.  {A7in.  Tharm.  57,  138.)   IT 

The  aqueous  solution  of  chloric  acid  is  colourless,  according  to  Gay- 
Lussac,  Vauquelin,  and  Berzelius;  but  according  to  Serullas,  it  is  yel- 
lowish when  concentrated,  even  when  not  strong  enough  to  precipitate 
nitrate  of  silver.  Tt  is  not  of  an  oily  consistence,  even  when  concen- 
trated; it  reddens  litmus-paper,  and  then  rapidly  bleaches  it  (Serullas); 
the  dilute  acid  reddens  litmus,  but  bleaches  it  only  after  the  lapse  of 
several  days.  (Vauquelin.)  The  concentrated  acid,  especially  when 
heated,  has  a  pungent  odour  resembling  that  of  nitric  acid  (Vauquelin ; 
Serullas) ;  the  cold  dilute  acid  is  inodorous.  (Gay-Lussac.)  It  has  a  very 
sour  and  astringent  taste.  (Vauquelin.)  Does  not  precipitate  salts  of 
lead,  mercury,  or  silver.  (Vauquelin.) 

The  aqueous  acid  is  not  decomposed  by  light.  (Gay-Lussac.)  It  is 
decomposed  when  heated  to  a  temperature  above  40°.  When  distilled,  it 
yields  nearly  pure  water  at  first,  then  aqueous  perchloric  acid,  with  dis- 
engagement of  chlorine  and  oxygen  gases,  but  no  chloric  acid.  (Serullas.) 


314  CHLORINE. 

Henoe,  while  one  portion  of  the  aoid  is  resolved  into  its  ultimate  elements, 
another  portion  is  conrerted  into  chlorine  and  perchloric  acid. 
7C10*  «  5C10T  +  2a. 

Salphorons  acid  decomposes  aqueons  chloric  acid,  forming  sulphnrio 
acid,  and  setting  chlorine  or  hydrochloric  acid  free,  according  to  the  pro- 
portions employed : 

5S0«  +  CIO'  =  5SO'  +  CI; 
and;  6SO«  +  C10»  +  HO  =  6SO»  +  HCl. 

Hydrosnlphurio  acid  and  aqueons  chloric  acid  decompose  each  other, 
yielding  water,  hydrochloric  acid,  and  sulphur,  or  water,  hydrochloric 
acid,  and  sulphuric  acid,  according  to  the  proportions  used : 

6HS  +  CIO*  «  5HO  +  HCl  +  6S; 
and:  3HS  +  2C10»  »  2HC1  +  HO  +  3S0>. 

With  hydrochloric  acid,  the  products  are  chlorine  and  water. 
5HC1  +  CIO*  =  5H0  +  6C1. 

(Gay-Lussac ;  Vauquelin.)  Phosphorous  acid  and  phosphuretted  hydrogen 
gas  likewise  hare  a  decomposing  action  on  chloric  acid.  (Berzelius.) 
Alcohol  and  ether  decompose  it  very  rapidly.  Bibulous  paper  folded 
several  times  together,  saturated  with  strong  chloric  acid,  and  then 
squeezed  out,  bums  with  a  vivid  light,  and  emits  a  strong  smell  of  chloric 
acid.  (Serullas.)  According  to  Gay-Lussac  and  Berzelius,  zinc  dissolves 
in  the  dilute  acid,  without  decomposing  it,  hydrogen  gas  being  evolved ; 
according  to  Vauquelin,  however,  no  hydrogen  gas  is  evolved,  but  hydro- 
chloric acid  is  formed.  According  to  the  author's  own  experiments,  both 
these  effects  take  place  simultaneousyl.  [For  the  decompositions  by 
nitric  acid  with  dezodizing  agents,  vid,  pp.  305,  306.] 

T  5.  With  Chlorous  Acid :  Chloro^Uoric  Acid,  2C10»,  C10».  This 
compound  is  obtained  by  passing  euchlorine,  the  gas  obtained  by  the  action 
of  hydrochloric  acid  on  chlorate  of  potash,  through  a  series  of  U-inhea 
cooled  by  freezing  mixtures,  the  first  to  O'',  the  second  to  —  1 8^  (0*^  F.). 
Hydrochloric  acid  collects  in  the  first,  and  a  red  liquid,  which  is  the 
chloro-chloric  acid,  in  the  second  and  third :  free  chlorine  escapes  at  the 
end  of  the  apparatus.  (Millon.) 

Chloro-chloric  acid,  in  appearance,  strongly  resembles  liquid  hypo- 
chloric  acid;  but  it  does  not  boil  below  32**  (89 '6°  F.),  or  explode  below 
TO"*  (158°  F.).  It  is  soluble  in  water.  The  solution  treated  with  caustic 
potash  behaves  like  hypochloric  acid,  forming  a  chlorite  and  a  chlorate ; 
but  the  quantity  of  chlorate  is  twice  as  great  as  in  the  case  of  hypochloric 
acid,  viz.  2  atoms  of  chlorate  to  1  atom  of  chlorite.  Henoe  the  composi- 
tion of  the  acid  is  determined  to  be  2C10*  -h  C10»  =  C1*0".  (Millon.)    T 

e.  With  salifiable  bases  chloric  acid  forms  the  Chlorates,  formerly  (»lled 
Hyper-oxymuriaU9,  Muriates  suroxyg^nSs.  These  salts  are  obtained: — 1. 
By  mixing  the  aqueous  acid  with  the  salifiable  base. — 2.  By  dissolving 
zinc  and  some  of  the  other  metals  in  the  dilute  acid. — 3.  In  company  with 
metallic  chlorides — from  which  they  may  be  separated  by  crystalbzation 
and  other  means— by  passing  chlorine  in  excess  through  a  caustic  alkali, 
or  alkaline  carbonate,  dissolved  or  diffused  in  water,  and  subsequently 
heating  the  liquid  (p.  299.)  Or  a  chloride  of  an  alkali  may  be  mixed 
with  excess  of  hypochlorous  acid,  and  exposed  for  a  long  time  to  the  sun's 
rays  or  the  heat  of  a  water-bath,  till  the  whole  is  converted  into  chlorate 
and  metallic  chloride;  the  hypochlorous  acid  may  afterwards  be  recovered 
by  distillation,  and  employed  to  act  on  £reeh  quantities  of  chloride.  (Gay- 
Lussac.) 


CHLORATES*  315 

All  chlorates  are  decomposed  by  heat— either  giving  off  the  5  atoms 
of  oxygen  of  the  chloric  acid,  and  the  one  atom  of  oxygen  of  the  base^  and 
leaving  metallic  chlorides  (the  alkali-metals,  lead,  silver,  &€.),  or — ^if 
the  metal  has  a  greater  affinity  for  oxygen  than  for  chlorine— evolving 
only  the  5  atoms  of  oxygen  belonging  to  the  chloric  acid,  and  leaving 
the  metal  in  the  state  of  oxide  (the  earth-metals).  Many  chlorates  (at 
least  the  potash-salt)  are  resolved,  at  the  temperature  at  which  the  evola- 
tion  of  oxygen  commences,  into  metallic  chloride  and  perchlorate.  With 
combustible  bodies,  such  as  charcoal,  phosphorus,  sulphur,  arsenic,  anti- 
mony, metallic  sulphides,  sugar,  &c.,  the  chlorates  explode — often  indeed 
with  the  greatest  violence — both  on  exposure  to  heat,  and  frequently  also 
by  a  blow — ^in  consequence  of  the  oxygen,  which  is  but  feebly  united,  with 
the  chlorine,  entering  into  a  state  of  more  intimate  combination  with  the 
combustible  body.  The  mixture  of  a  chlorate  with  a  combustible  sub- 
stance is  often  partially  inflamed  by  oil  of  vitriol,  probably,  because 
that  acid  disengages  chloric  oxide,  which  readily  gives  up  its  oxygen  to 
the  inflammable  substance.  The  inflammation  with  oil  of  vitriol  does 
not  take  place  in  vacuo.  (Hearder,  J.  pr,  Chem.  26,  258.)  Dry  oxide  of 
lead  when  heated  with  a  dry  chlorate,  is  converted  into  peroxiae ;  sesqui- 
oxide  of  manganese,  if  an  alkali  be  present,  into  manganic  acid,  &c.  Oil 
of  vitriol  decomposes  the  chlorates,  even  at  ordinary  temperatures,  into 
chloric  oxide  sas  (which  is  partly  absorbed  by  the  oil  of  vitriol,  forming 
a  brownish-yellow  solution,  and  is  mixed  with  a  small  quantity  of  chlo- 
rine^ and  according  to  Sir  H.  Davy,  -^  of  its  volume  of  oxygen  gas)  and 
a  mixture  of  sulphate  and  perchlorate.  (Vid,  p.  312.)  Moreover,  the  heat 
disengaged  frequently  gives  rise  to  sudden  decomposition  of  the  chloric 
oxide,  producing  decrepitation,  detonation,  and  flashes  of  light.  (Chene- 
vix;  Sir  H.  Davy;  Stadion.)  A  mixture  of  equal  parts  of  oil  of  vitriol 
and  water,  does  not  act  perceptibly  on  chlorate  ot  potash,  at  ordinary 
temperatures,  unless  chloride  of  potassium  is  present :  in  the  latter  case, 
chloric  acid  and  hydrochloric  acid  are  set  free,  which  react  on  each  other 
in  atomic  proportions,  and  yield  equal  measures  of  chloric  oxide  and 
chlorine  gas.  (Martens.)  The  solution  of  a  chlorate  in  a  moderate  quan- 
tity of  water,  mixed  cold  with  tincture  of  litmus,  and  then  with  oil 
of  vitriol,  discharges  the  colour  of  the  litmus  (a  distinguishing  character 
between  the  chlorates  and  the  nitrates).  (Vogel,  Junior.)  An  aqueous 
solution  of  a  chlorate,  mixed  with  oil  of  vitriol,  bleaches  tincture  of  indigo, 
on  the  application  of  heat,  in  the  same  manner  as  the  nitrates.  (Orfila.) 
Nitric  acid  likewise  decomposes  the  chlorates,  evolving  chloric  oxide  gas 
mixed  with  chlorine,  and  ■)•  of  its  volume  of  oxygen  gas.  (H.  Davy.) 
Chlorate  of  potash  or  soda,  heated  to  dryness  with  nitric  acid,  evolves  a 
mixture,  containing  6  measures  of  chlorine  to  13  measures  of  oxygen,  and 
leaves  3  atoms  of  nitrate  to  one  atom  of  perchlorate. 

4(K0,C10»)  +  3N0»=  3(KO,NO«)  +  KO,  CIO'  +  3a  +  130. 

(Penny,  Ann.  Pharm,  37,  203;  also  J.  pr.  Chem.  23,  296.)  Hydrochloric 
acid  when  gently  heated  with  a  chlorate,  evolves  a  mixture  of  2  measures 
of  chloric  oxide  gas  and  3  measures  of  chlorine,  in  the  form  of  euohlorine. 
(p.  304).  Phosphoric,  arsenic,  oxalic,  citric,  and  tartaric  acids,  with  the 
aid  of  heat,  produce  simiUr  results.  Acetic  and  benzoic  acids  do  not 
affect  the  chlorates.  (Chenevix.)  Hydrosulphurio  acid,  arsenious  acid, 
and  protochloride  of  tin,  likewise  produce  no  action  on  an  aqueous  solution 
of  chlorate  of  potash,  even  when  aided  by  heat     All  chlorates  are  soluble 


316  CHLORINE. 

in  water^  the  least  soluble  being  the  chlorate  of  potash;  most  of  them 
dissolve  so  readily,  that  they  deliqnesce  in  the  air.  Their  aqueous 
solutions  do  not  precipitate  the  salts  of  any  heavy  metal,  and  conse- 
quently do  not  affect  silver  salts.  This  character  affords  the  means  of 
detecting  a  chloride  mixed  with  a  chlorate,  and  likewise  distinguishes  the 
chlorates  from  the  broroates  and  iodates.  The  aqueous  solutions  of  the 
chlorates  do  not  discharge  vegetable  colours,  unless  a  free  acid  is  present. 
Many  chlorates  are  soluble  in  alcohol. 


E.    Perchloric  Acid. 

Ueberchlorsaure,  Oxidized  Chloric  add,  Adds  perchlorique,  Adde  Marique 
oxigini,  Addum  oxyckUyricum, 

Formation, — 1.  In  the  circuit  of  the  voltaic  battery,  chloric  oxide 
evolves  scarcely  any  gas  at  first;  but  after  some  hours,  it  gives  off  a  small 
quantity  of  oxygen  and  chlorine  at  the  positive  pole,  and  hydrogen  gas  at 
the  negative  pole,  the  volume  of  the  latter  being  more  than  double  that 
of  the  oxygen  disengaged  at  the  positive  pole.  After  some  time,  the 
liquid  becomes  colourless,  and  is  converted  into  a  solution  of  perchloric 
acid.  (Stadion.) — 2.  When  aqueous  solution  of  chloric  acid  is  distilled, 
perchloric  acid  passes  over  into  the  receiver.  (Serullas.)— 3.  Oil  of  vitriol 
decomposes  chlorate  of  potash  at  a  gentle  heat  into  chloric  oxide  gas, 
perchlorate  of  potash  and  bisulphate  of  potash.  (Stadion,  p.  309.) 
4.  Chlorate  of  potash  when  fused  and  kept  for  some  time  in  a  state  of 
ebullition  is  resolved  into  oxygen  gas  and  a  mixture  of  chloride  of  potas- 
sium and  perchlorate  of  potash,  the  latter  of  which  amounts  to  about 
half  the  quantity  of  chlorate  employed.  (Serullas.) 

Not  known  in  the  separate  state. 

Calculation  according  to  Stadion.  Volume. 

CI 35-4  38-7  Chlorine  gas 1 

70 56-0  61-3  Oxygen  gas  3'5 

ClOr  ....  91-4  1000 

(CIW  =  2  .  221-33  +  7  .  100       1142*66.     BerzeUus.) 

Combinations,  a.  With  Water.  «.  Crystallized  Perchloric  add. 
— 1.  To  prepare  this  substance,  the  aqueous  acid  is  first  concentrated  by 
evaporation  till  it  gives  off  abundant  white  fumes;  it  is  then  (in  quantity 
not  exceeding  10  grammes)  mixed  with  between  4  and  5  times  its  volume 
of  oil  of  vitriol,  and  the  whole  poured  into  a  plain  retort  by  means  of  a 
tube-funnel.  The  neck  of  the  retort  is  then  passed,  without  any  cork  or 
lutinff,  into  a  bent  tube,  which  is  drawn  out  at  the  other  end  to  a  nne  point, 
and  kept  cool  by  water :  the  mixture,  which  rapidly  assumes  a  yellow 
colour,  is  kept  in  a  state  of  moderate  ebullition,  till  the  drops  which  distil 
over  no  longer  solidify,  in  consequence  of  their  containing  too  much  water. 
The  greater  part  of  the  acid  is  decomposed,  and  escapes  in  the  form  of 
chlorine  and  oxygen  gases;  but  a  portion  slowly  runs  into  the  tube,  and 
there  solidifies.  (Serullaa.) — 2.  140  parts  (one  atom)  of  perchlorate 
of  potash  is  distilled  with  196  parts  (4  atoms)  of  oil  of  vitriol  at  a 
gentle  heat.  The  mass  melts  (which  is  not  the  case  when  only  2  atoms 
of  oil  of  vitriol  are  used),  and  the  acid  solidifies  in  tiie  neck  of  the  retort, 


PERCHLORIC  ACID.  317 

\7hich  is  kept  cool  for  the  purpose ;  the  product,  however,  is  but  small. 
(Weppen,  Anv.  Pkarm.  29,  318.)  White,  micaceous,  or  crystallized 
mass,  or  sometimes  long,  four-sided  prisms  with  dihedral  summits. 
Fuses  at  45°.  Emits  white  fumes  in  the  air,  and  rapidly  deliquesces. 
When  the  fused  acid  is  dropped  into  water,  each  drop  makes  a  hissing 
noise  like  red-hot  iron.  (Serullas.) 

/9,  Aqueous  Perchloric  acid, — 1 .  An  aqueous  solution  of  chloric  acid  is 
submitted  to  the  action  of  a  voltaic  battery.  (Vid.  Formation  of  Perchloric 
a^d.)  (Stadion.) — 2.  Aqueous  chloric  acid  is  distilled,  the  receiver  being 
changed  during  the  process,  and  the  heat  increased  till  the  whole  has 
passed  over.  The  first  products  are  water  and  chlorine;  afterwards  a 
quantity  of  strong  perchloric  acid  is  obtained,  amounting  to  one-third  of 
tne  chloric  acid  originally  employed.  (Serullas.) — 3.  A  mixture  of  2  parts 
of  perchlorate  of  potash  with  2  parts  of  oil  of  vitriol  and  1  part  of  water  is 
heated  in  a  tubulated  retort  to  a  temperature  of  138°  (280°  F).  Water 
distils  over  first,  then  aqueous  perchloric  acid,  and  lastly,  a  small  quantity  of 
chlorine,  easily  disengaged.  The  distilled  acid  is  freed  from  sulphuric  and 
hydrochloric  acids  by  means  of  baryta-water  and  oxide  of  silver,  and  con- 
centrated by  careful  evaporation.  (Stadion.)— 4.  In  a  retort  which  is 
connected  with  a  tube-funnel,  then  with  a  long  tube,  and  then  with  a 
tubulated  receiver  immersed  in  cold  water — ^without  the  use  of  any  luting, 
or,  at  all  events,  only  of  asbestos — 5  parts  of  perchlorate  of  potash  are  care- 
fully heated  with  a  mixture  of  10  parts  of  oil  of  vitrioi  perfectly  free 
from  nitric  acid,  and  1  part  of  water,  f  if  less  oil  of  vitriol  is  employed, 
less  acid  is  obtained).  The  mixture  is  never  allowed  to  boil,  and  the 
heat  is  continued  till  the  transparent  fluid  residue  becomes  colourless,  and 
the  drops  of  distillate  follow  each  other  very  slowly,  even  when  the  tem- 
perature is  somewhat  raised.  The  distillate,  which  amounts  to  about  3 
parts,  of  a  density  corresponding  to  45°  B.  is  purified  from  free  chlorine  and 
sulphuric  acid  by  precipitating  it  with  a  saturated  solution  of  sulphate  of 
silver,  filtering  mto  a  basin,  and  mixing  it  with  such  a  quantity  of  freshly 
precipitated  and  well  washed  carbonate  of  baryta,  that  the  whole  of  the 
sulphuric  acid  may  be  retained,  and  a  small  quantity  of  perchlorate  of 
baryta  formed.  The  solution  is  lastly  distilled  in  a  retort  connected  with 
the  same  apparatus  as  above,  at  a  very  slowly  increasing  heat.  The 
greater  part  of  the  water  passes  over  first,  and  afterwards  concentrated 
perchloric  acid,  which  is  collected  apart,  and  amounts  to  1*5  parts.  The 
distillation  is  carried  nearly  to  dryness :  by  heating  the  residue  longer, 
the  perchlorates  of  silver  and  baryta  woum  be  decomposed,  and  evolve 
chlorine.  (Nativelle,  J.  Pharm.  28,  498.) — 5.  Perchlorate  of  potash  is 
briskly  boiled  with  excess  of  hydrofluosilicic  acid,  whereupon  gelatinous 
double  fluoride  of  silicium  and  potassium  separates  as  the  liquid  cools ;  the 
solution  is  then  filtered,  evaporated,  cooled,  refiltered,  again  evaporated, 
and  lastly  distilled.  Serullas  gives  the  preference  to  this  method. — 6.  An 
aqueous  solution  of  perchlorate  of  baryta  is  decomposed  by  an  equivalent 
quantity  of  sulphuric  acid,  and  the  solution  filtered.  (0.  Henry^  J.  Phami, 
25,  268;  also  Ann,  Pharm.  31,  345.) 

The  dilute  acid  is  best  concentrated  by  careful  evaporation  in  a  retort, 
whereby  a  distillate  is  obtained  consisting  of  nearly  pure  water :  if  the 
acid  appears  of  a  rose-colour,  arising  from  the  employment  of  chlorate  of 
potash  containing  manganese,  in  its  preparation,  it  must,  when  concen- 
trated, be  purified  by  distillation.  (Serullas.) 

The  most  concentrated  acid  has  a  specific  gravity  of  1*65 ;  it  is  colour^ 
less,  fumes  slightly  in  the  air,  and  boils  at  200''.  (Serullas.)     It  is  oily, 


318  CHLORINE. 

like  oil  of  vitriol,  and  has  a  density  between  60^  and  65^  B.  (Natiyelle.) 
Perchloric  acid  is  inodorons,  has  a  strong  and  agreeably  acid  taste,  reddens 
litmns  without  bleaching  it,  and  volatilizes  at  about  138^  without  being 
decomposed.  It  is  likewise  unaffected  by  exposure  to  the  sun's  rays,  and 
is  not  decomposed  by  hydrosulphurio,  sulphurous,  or  hydrochloric  acid. 
(Stadion.)  Neither  is  it  decomposed  when  heated  with  hydrochloric  acid 
or  with  alcohol.  Paper  saturated  with  the  strong  acid  does  not  take  fire 
spontaneously,  but  when  brought  in  contact  with  red-hot  charcoal,  it 
emits  bright  sparks  accompanied  by  detonation.  Paper  held  in  the  vaponr 
of  perchloric  acid  boiling  in  a  tube,  takes  fire  and  burns  yividly.  The 
concentrated  acid  absorbs  water  from  the  air.  (Serullas.) 

b.  With  Chlorous  Acid:  Chlor<hperchlorie  Acid.  2C10',C10».  Formed 
by  the  action  of  lieht  on  chlorous  acid.  When  chlorous  acid  gas  con- 
tained in  a  perfectly  dry  bottle  is  exposed  to  the  direct  rays  of  the  sun, 
it  is  converted  in  a  short  time  into  perchloric  acid,  chlorine,  and  oxygen. 
The  same  decomposition  takes  place,  though  less  quickly,  in  diffused 
daylight.  But  if  the  action  of  the  light  be  modified  by  immersing  the 
bottle  containing  the  dry  gas  in  water  of  the  temperature  of  20°  (68"^  F.) 
no  perchloric  acid  is  formed,  but  in  its  stead  a  reddish-brown  liquid, 
which  runs  down  the  sides  of  the  vessel.  The  rays  of  the  morning  sun 
are  more  effective  in  producing  this  substance  than  those  of  the  sun  at 
noon.  The  liquid  thus  formed  is  the  chloro-perchloric  acid.  It  is  decom- 
posed by  heat,  but  not  explosively.  In  contact  with  moist  air,  it  fumes 
so  strongly  that  a  few  drops  of  it  exposed  in  a  room,  the  floor  of  which 
has  been  recently  sprinkled  with  water,  are  sufficient  to  fill  the  whole 
space  with  a  white  mist.  This  is  probably  the  cause  of  the  dense  fumes 
produced  by  dropping  a  dilute  solution  of  chlorous  acid  into  a  bottle  filled 
with  moist  air  (p.  808),  the  chlorous  acid  being  converted  into  chloro- 
perchloric  acid  by  the  influence  of  light.  With  caustic  potash  this  acid 
forms  2  atoms  oi  perchlorate  and  1  atom  of  chlorate :  hence  its  composi- 
tion is  2C10'  -f  CIO*  =  CP  0". 

c.  With  Salifiable  Bases.  Salts  of  Pereklaric  acid,  Perchlorates. 
Perchloric  acid  has  a  powerful  affinity  for  salifiable  bajses.  The  salts 
are  obtained  either  by  mixing  the  acid  and  base,  or  by  the  methods 
described  when  speaking  of  the  formation  of  the  acid  {vid.  p.  316; 
also  Perchlorate  of  Potash  and  Perchlorate  of  Baryta),  Other  salts  of 
perchloric  acid  may  be  obtained  by  precipitating  the  potash-salt  by 
hydrofiuosilicates  or  the  baryta-salt  by  sulphates.  To  obtain  the  deli- 
quescent perchlorates  in  a  crystallized  state,  Serullas  leaves  their  alcoho- 
lic solution  to  evaporate  in  vacuo.  The  perchlorates  require  a  greater 
heat  to  decompose  them  than  the  chlorates,  but  the  decomposition  takes 
place  in  a  similar  manner,  the  salts  being  resolved  either  into  metallic 
chlorides  and  oxygen  gas,  or  metallic  oxides,  oxygen,  and  chlorine. 
They  explode  violently  on  ignited  charcoal ;  but,  according  to  Stadion, 
the  explosion  is  less  violent  with  combustible  bodies  than  that  of  the  chlo- 
rates. Hydrosulphuric  acid  does  not  decompose  their  aqueous  solutions. 
They  are  not  decomposed  by  the  strongest  acids,  not  even  by  sulphuric 
acid,  below  100°.  (Stadion.)  Consequently  they  do  not  assume  a  yellow 
colour  on  the  addition  of  oil  of  vitriol  or  hydrochloric  acid :  this  character 
distinguishes  them  from  the  chlorates.  (Serullas.)  All  the  perchlorates 
are  soluble  in  water  (Stadion),  and  likewise  deliquescent,  with  the  excep- 
tion of  the  salts  of  ammonia,  potassa,  lead,  and  mercurous  oxide  (Serul- 
las) ;  the  potash-salt  is  the  most  sparingly  soluble  of  all.  Hence  per- 
chloric acid  precipitates  perchlorate  of  potassa  from  the  potash-salts  and 


HYDROCHLORIC  ACID.  339 

%  small  quantity  even  from  a  solution  of  cream  of  tartar.  (Serullas.)  A 
solution  of  a  perchlorate  does  not  precipitate  the  salts  of  any  of  the 
heavy  metals.  (Stadion.)  The  deliquescent  salts  are  likewise  soluble  in 
alcohol;  the  potash-salt  is  insoluble  in  this  menstruum. 

That  perchloric  acid,  notwithstanding  the  larger  quantity  of  oxygen 
which  it  contains^  is  decomposed  with  less  &cility  than  chloric  acid,  when 
combined  with  water  or  with  salifiable  bases,  is  doubtless  to  be  attributed 
to  the  fact  of  its  being  a  stronger  acid,  and  consequently  retained  by 
water  and  salifiable  bases  with  greater  force. 


Chlorine  and  Hydrogen. 

Htdrochlorio  Acid. 

Muriatic  acid,  ffydrochlarsaure,  Chlorwasserstqfsaure,  ScUaaure,  Koch- 
scUzsaure,  Seesaluaure,  Acide  muricUique,  Acide  hydrachlorique,  Acide 
chlarhydrique,  Acidum  $alisB.  muriaHcum;  and  in  the  gaseous  form: 
Hydrochloric  acid  gas,  Muriatic  add  gas,  Hydrochlorgas,  Chlarwas* 
serstqfgas,  Gas  acide  muriatique.  Gas  acidum  muriaticum, — Found  in 
the  gaseous  form  in  the  vapours  emitted  from  voloanos. 

FormcUion,  1.  When  a  mixture  of  equal  volumes  of  chlorine  and 
hydrogen  is  exposed  to  the  sun's  rays,  it  instantly  explodes,  with  disen- 
gagement of  light  and  heat,  and  is  converted  into  hydrochloric  acid  gas; 
a  ^ebler  lieht,  such  as  diffused  daylight,  induces  slow  combination.  The 
two  gases  do  not  unite  in  the  dark.  (Qay-Lussao  A  Th^nard.)  In  many 
instances,  the  combination  which  takes  place  on  exposure  to  the  sun,  is 
not  sudden  but  gradual :  this  was  found  to  be  the  case  by  Bischof  (Kastn, 
Arch.  1,  443,  and  in  his  Lehrbtich,  I,  98^,  and  likewise  by  the  author^ 
especially  in  winter.  In  one  experiment  of  Bischof  s,  the  gaseous  mixture 
did  not  explode  on  exposure  to  the  sun's  rays  on  a  clear  day  in  winter, 
even  though  the  water  surrounding  the  bottom  of  the  receiver  was  heated 
as  hot  as  the  hand  could  bear  it.  On  the  other  hand,  explosion  sometimes 
takes  place  in  diffused  daylight;  as  in  an  experiment  of  Silliman's,  when 
the  air  was  filled  with  thick  snow-flakes.  (8UL  Amer.J.  3,  343;  also 
Ann.  PhU.  19,  153;  also  N.  Tr.  7,  2,  161.)  The  same  thin^  happened 
in  the  author's  hands,  on  a  fine  day  in  summer,  as  he  was  mixmg  the  two 
gases  in  the  open  air  under  the  shadow  of  a  house,  with  the  intention  of 
subsequently  removing  the  receiver  into  the  sunshine.  Liebig  also  {Pogg. 
24,  281)  found  that  the  mixture  could  be  exploded  by  the  warmth  of  the 
hand  without  the  influence  of  the  sun's  rays.  A  mixture  of  1  volume  of 
hydrogen  with  1^  vol.  of  chlorine  explodes  even  in  diffused  daylight; 
a  mixture  of  equal  volumes,  only  in  sunshine.  (Dobereiner,  Pogg,  25, 
189.)  Explosion  in  the  sunshine  takes  place  when  the  mixture  is  con- 
tained in  a  vessel  of  white  glass ;  under  dark  blue  glass,  combination 
ensues,  without  explosion,  in  the  course  of  a  minute;  under  red  glass,  not 
at  all,  or  but  very  slowly.  (Seebeck.)  On  a  bright  day  in  summer,  explo- 
sion occurred  in  an  experiment  of  Bischofs,  even  under  blue  glass.  A 
mixture  of  1  volume  of  hydrogen,  with  between  1^  and  2  volumes  of 
chlorine,  explodes  when  exposed  to  sun-light  dimmed  by  clouds,  also  when 
contained  in  green  medical  bottles,  and  when  exposed  to  the  red  light  of 
early  morning.     A  mixture  of  equal  volumes  of  chlorine  and  hydrogen 


320  CHLORINE. 

explodes  ouly  in  the  direct  rays  of  the  san,  whether  it  be  contained  in 
coloarlcss,  in  violet,  or  in  blue  glasses ;  the  same  mixture  exposed  to  sun- 
shine in  green  or  red  glasses,  or  to  diffused  daylight  in  colourless  glasses, 
combines  slowly ;  and  when  it  is  exposed  to  sunshine  in  oranffe-cnloured 
glasses,  no  combination  takes  place.  (Succow,  Fogg.  32,  387.)  Accord- 
ing to  Seebeck,  the  light  from  Indian  white  fire  causes  explosion ;  also, 
according  to  Drummond  {Fogg,  9, 171),  the  light  from  lime  ignited  by  the 
oxygen  blow-pipe  (p.  29) :  according  to  Bischof,  however,  explosion  16 
not  produced  either  by  the  light  of  Indian  white  fire,  or  by  that  of  phos- 
phorus burning  in  oxygen  gas  on  each  side  of  the  gaseous  mixture. 
Brande  {Ann,  Chim,  Phys,  19,  205)  produced  combination,  frequently 
attended  with  explosion,  by  the  vivid  light  of  charcoal  ignited  by  a  vol- 
taic battery,  but  not  by  the  light  disengaged  in  the  combustion  of  olefiant 
gas.  Combination  attended  with  violent  explosion  also  takes  place  when 
a  piece  of  brick  heated  to  150°  or  a  burning  body  is  introduced  into  the 
mixture,  or  when  the  mixture  is  transmitted  through  an  ignited  tube,  or 
when  an  electric  spark  is  passed  through  it.  (Gay-Lussac  &  Thenard.) 
Sudden  combination  accompanied  by  a  flashing  light  is  produced  by  the 
electric  spark,  even  when  the  mixture  is  24  times  diluted:  1  volume  of 
the  mixture  diluted  with  18  volumes  of  oxygen  gas  is  still  capable 
of  taking  fire  in  this  manner.  (H.  Davy.)  BlundeU's  statement  that 
spongy  platinum  causes  combination,  is  contradicted  by  Dobereiner  and 
Faraway. 

2.  Chlorine,  in  consequence  of  its  great  affinity  for  hydrogen,  decom- 
poses all  hydrogen  compounds  with  the  exception  of  hydrofluoric  acid. 
It  does  not,  however,  decompose  pure  water  in  the  dark,  but  slowly  under 
the  influence  of  light,  even  of  diffused  daylight,  and  more  rapidly  at 
a  red  heat  (when  a  mixture  of  chlorine  and  aqueous  vapour  is  passed 
through  a  red-hot  porcelain  tube),  oxygen  gas  being  set  free  (I.,  129). 
If  besides  chlorine  and  water,  there  is  likewise  present  a  body  which  has 
some  affinity  for  the  oxygen  of  the  water,  such  as  boron,  phosphorus,  sul- 
phur, selenium,  iodine,  phosphorous  acid,  sulphurous  acid,  metals,  and 
organic  substances  (from  the  carbon  they  contain),  the  water  is  very 
readily  decomposed,  with  oxidation  of  the  third  substance  and  formation 
of  hydrochloric  acid.  Chlorine,  even  at  ordinary  temperatures,  combines 
with  the  hydrogen  of  phosphuretted  and  arseniuretted  hydrogen,  hydro- 
sulphuric  acid,  hydriodic  acid,  ammonia,  and  a  great  many  organic  com- 
pounds, namely,  alcohol,  ether,  volatile  oils,  fats  and  resins ;  olefiant  gas 
is  decomposed  by  chlorine  only  at  high  temperatures;  and  marsh-gas,  in 
the  sun's  rays,  with  explosion.  (Gay-Lussac  &  Thenard.) 

Preparation,  1.  In  tlie  gaseous  form.  Common  salt  is  mixed  with 
an  equal  weight  of  oil  of  vitriol  in  a  gas-generating  apparatus,  and  the 
mixture  gradually  and  gently  heated.  (Scheme  50.)  The  gas  is  received 
over  mercury. 

2.  In  Hie  liquid  state,  (  Vid,  I.,  286  and  287.) 

Properties.  In  the  liquid  state  it  forms  a  colourless  fluid,  whose  refrac- 
tive power  is  equal  to  that  of  liquid  carbonic  acid.  (Faraday.)  Refracts 
light  less  powerfully  than  water,  but  more  so  than  liquid  carbonic  acid. 
Is  of  a  pale  yellow  colour  when  first  formed,  but  becomes  colourless  on 
exposure  to  light,  a  proof  that  the  colour  is  not  essential  to  it,  and  pro- 
bably arises  from  organic  matter  in  the  dust  collected  in  the  tube  [from 
combustible  matter  in  the  sal  ammoniac?].  (Niemann.  Br,  Arch,  36,  185; 


HYDROCHLOKIC  ACID.  321 

Ann.  Pharm.  I,  32.)  (For  the  tension,  specific  gravity^  and  refractire 
power,  vid.  I.,  261,  279,  95.)  The  gas  is  colourless.  Fumes  in  moist  air; 
has  a  peculiar,  acid,  and  suffocating  odour;  is  irrespirable ;  causes  inflam- 
mation and  itching  of  the  skin.  Reddens  litmus  strongly.  Incombustible; 
extinguishes  a  burning  taper,  but  the  flame,  before  extinction,  exhibits  a 
greenish  border. 

Calciilation.  Yolame.      Sp.  gr. 

CI 35-4  97-25  Chlorine  gas  1  2-4543 

H I'D  2-75  Hydrogen  gag    1  0-0693 

HCl  ....  36-4  100-00  Hydrochloric  add  gas  .  2  1-2618 

HCl  =  6-24  +  221-33  =  227-57.    (BerieUm.) 

Decompontions,'-^!.  Hydrochloric  acid  gas  is  decomposed  by  the  elec* 
trie  spark ;  but  the  quantity  decomposed  never  exceeds  -^  of  the  whole, 
for  whatever  time  the  passage  of  the  sparks  may  be  continued  (W. 
Henry) ;  for,  on  the  other  hand,  the  electric  spark  causes  the  separated 
gases  to  recombine  (vid,  p.  320).  [For  the  decomposition  of  the  aqueous 
acid  by  a  current  of  electricity,  vid.  I.,  455.] — 2.  A  mixture  of  hydro- 
chloric acid  gas  with  4  vol.  oxygen,  yields  water  and  chlorine  nis  when 
electrifled  ;  spongy  platinum  likewise,  when  gradually  heated  in  this 
mixture,  begins,  at  a  temperature  of  120°,  to  form  water  and  liberate 
chlorine  gas.  (W.  Henry.) — 3.  Hydrochloric  acid  and  sulphurous  acid  do 
not  act  on  each  other  in  the  state  of  solution,  but  when  mixed  perfectly 
diy  in  the  gaseous  form  over  mercury,  they  are  resolved  into  water,  chlo- 
rine, and  sulphur.  (Dumas,  Traits  de  Chim.  1,  146.)— 4.  A  mixture  of  2 
volumes  of  hydr6chloric  acid  gas  and  1  volume  of  hypochlorous  acid  gas 
is  resolved,  with  disengagement  of  heat,  into  1  volume  of  aqueous  vapour 
and  2  volumes  of  chlorine  ffas.  Hydrochloric  acid  gas  acts  in  a  similar 
manner  on  an  aqueous  solution  of  hypochlorous  acid.  (Balard.)  By 
atoms  : 

Ha  +  ao  =  HO  +  2C1; 
By  volume :  2  vol.  hydrochloric  acid  gas  contain  1  vol.  chlorine  and 
1  vol,  hydrogen ;  1  vol.  hypochlorous  acid  gas  contains  1  vol.  chlorine  and 
^  vol.  oxygen ;  1  vol.  hydrogen  with  \  vol.  oxygen  forms  1  vol.  vapour 
of  water;  and  2  vol.  chlorine  are  set  free. — 5.  Metals,  viz.  potassium 
at  ordinary  temperatures,  zinc  {Scheme  9)  tin,  drc,  with  the  aid  of  heat, 
and  mercuiT,  especially  when  electrolized,  decompose  1  volume  of  hydro- 
chloric acid  gas  into  metallic  chloride  and  a  half  volume  of  hydrogen 
gas. — 6.  Many  salifiable  metallic  oxides  (the  earths  excepted)  act  on 
hydrochloric  acid  gas,  sometimes  at  ordinary,  sometimes  at  rather  ele- 
vated temperatures,  producing  water  and  anhydrous  metallic  chlorides. 
Under  these  circumstances,  biuryta  and  strontia  become  red  hot,  and  lime 
disengages  considerable  heat.  (Chevreul,  Ann.  Chim.  84,  285.)  With 
the  aqueous  acid,  only  oxide  of  lead,  the  dioxides  of  copper  and  mercury 
and  oxide  of  silver,  form  anhydrous  chlorides ;  all  other  oxides  yield  solu- 
tions which  may  be  regarded  either  as  aqueous  metallic  chlorides,  or  as 
solutions  of  hydrochlorates  of  the  oxides. — 1 .  With  metallic  peroxides 
and  some  of  the  metallic  acids,  as  with  peroxide  of  manganese,  peroxide 
of  lead,  chromic  acid,  &c.,  hydrochloric  acid  gas  and  aqueous  hydrochloric 
acid  yield  chloride  of  the  metal  (or  hydrochlorate  of  the  oxide)  and 
free  chlorine: 

MnO*  +  2HC1  =  MnCl  +  2H0  +  CI. 
Charcoal,  phosphorus,  and  sulphur,  do  not  act  on  hydrochloric  acid  at  any 
temperature. 

VOL.    IT.  Y 


822  CHLORINB. 

C<mMn<Uion$.  a.  With  Water.  Aqusoui  Hydroekhrie  add^  Hydro- 
Moric  acid  in  general.  Muriatic  acid,  Liquid  Muriatic  aeid,  Spirit  of 
Salt,  Aeid  Spirit  of  Salt,  Fuming  Spirit  of  Salt,  Spiritu*  sali$  acidu$, 
fumans. 

Hjdrochlorio  add  ga«  condenaef  with  the  aqneons  vaponr  of  the  air, 
forming  cloadB  of  aqaeoos  hydrochloric  acid ;  it  \a  rapidlj  absorbed  by 
ice,  the  ice  melting  at  the  same  time;  it  ib  taken  np  still  more  rapid Ij  by 
water,  with  considerable  rise  of  temperature.  Water  absorbs  not  quite 
its  own  weight  of  hydrochloric  acid  gas  :  according  to  Sir  H.  Davy, 
water,  at  ordinary  temperatures,  absorbs  480  times  its  volume  of  the  gas, 
and  thereby  acquires  a  specific  gravity  of  1*2 109. 

Preparation.  In  a  tflaas  vessel  a  {App.  50,)  8  parts  of  common  salt 
are  treated  with  a  cold  mixture  of  13  parts  of  oil  vitriol  and  3  parts 
water,  the  vessel  connected  by  means  of  three  bent  tubes — ^the  second  of 
which  is  a  Welter's  safetv  tube— with  three  Woulfe's  bottles,  which  are 
immersed  in  water  and  surrounded  at  top  with  moistened  bibulons 
paper.  The  first  bottle  h  contains  a  very  small  quantity  of  water,  the 
second  0,  a  quantity  of  distilled  water  about  equal  to  that  of  the  common 
ealt  emploved,  and  the  third  d,  somewhat  less.  The  vessel  a  is  gradu- 
ally heated  in  a  sand-bath,  or  over  an  open  fire,  not  auite  to  redness,  till 
aqueous  vapour  is  no  longer  given  off.  The  acid  which  collects  in  the 
first  bottle  is  diluted  by  the  aqueous  vapour  which  passes  over  at  the 
end,  and  also  contaminated  with  less  volatile  substances,  such  as  sele- 
nium, chloride  of  arsenic,  chloride  of  tin,  and  chloride  of  iron.  The  8 
parts  of  water  in  the  second  bottle  are  converted  into  about  13  parts  of 
pnre  aqueous  hydrochloric  acid,  of  specific  gravity  1*145;  if  the  oil  of 
vitriol  contains  nitric  acid,  the  hydrochloric  acid  may  be  contaminated 
with  free  chlorine.  The  water  in  the  third  bottle  absorbs  the  small  quan- 
tity of  hydrochloric  acid  which  has  not  been  taken  up  by  the  second,  and 
in  a  subsequent  operation  may  be  further  concentrated  in  the  second  bottle. 
When  a  still  stronger  acid  is  required,  less  water  is  introduced  into  the 
second  bottle.  Nothing  is  gained  by  heating  the  salt  to  decrepitation 
before  using  it.  Undiluted  oil  of  vitriol  is  not  well  adapted  for  the  pro- 
eess,  because  it  disengages  a  large  quantity  of  hydrochloric  acid  as  soon  as 
it  comes  in  contact  with  the  salt,  and  even  before  the  apparatus  is  connected; 
also  because  the  mass  is  more  liable  to  boil  over  when  heated.  With  1  atom 
of  oil  of  vitriol  to  1  atom  of  common  salt  (49  :  60  parts)  the  hydro- 
chloric fusid  is  far  from  being  entirely  evolved;  the  residue  in  this  case  is 
a  mixture  of  bisulphate  of  soda  and  undecomposed  common  salt;  with  1^ 
atoms  of  oil  of  vitriol,  about  i  only  of  the  hydrochloric  acid  is  obtained; 
but  with  2  atoms  of  oil  of  vitriol  to  1  atom  of  common  salt  (98  :  60 
parts)  the  decomposition  is  complete,  and  requires  only  a  moderate  tem- 
perature ;  moreover,  the  residue  of  bisulphate  of  soda  remains  semifluid 
even  after  cooling,  and  is  therefore  easily  poured  out.  (  Vid,  Geiger,  N. 
Tr.  3,  1,  462  and  4,  2,  462;  Wittstein,  Bepert.  63,  225;  Gregory,  Ann. 
Pharm.  41,  375.) 

Commereial  HydroMoric  Add  is  prepared  on  the  large  scale  by  heat- 
ing a  mixture  of  t  atom  of  common  salt  with  1  atom  of  oil  of  vitriol 
or  more  dilute  sulphuric  acid  in  horizontal  cast  iron  cylinders  (glass 
retorts  or  cast  iron  or  leaden  boilers  are  not  so  much  used).  The  gas 
evolved  is  generally  conducted  by  means  of  bent  tubes  into  a  series  of 
bottles  containing  water ;  or  into  a  long,  gradually  rising,  bricked  chan- 
nel, in  which  a  email  current  of  water  is  made  to  trickle  down  and  meet 
the  gas. 


HYDROCHLORIC  ACID.  389 

Impurities  in  aqneoiu  hydrochlorio  aoid,  espedallj  itx  the  oommeroitl 
aoid: 

StUphurotu  acid:  ehieflj  prodaced  bj  the  action  of  the  sulphuric  acid 
on  the  iron  at  a  high  temperature.  The  hydrochlorio  acid  becomes  turbid 
on  mixing  it  with  ^  pt.  of  tin  salt  and  2  parts  of  water^  often  after 
some  minutes  only;  the  liquid  appears  yellow  at  first,  then  brown,  and 
finally  deposits  brown  sulphide  of  tin.  mirardin, «/.  Pharm.  21,  161;  also 
«/.  pr.  Chem.  6,  81.)  Decolorizes  sulphate  of  manganic  oxide  (Gay- 
Lussac)  (an  effect,  howerer,  which  is  produced  when  nitrous  acid  is  pre* 
sent).  Uives  a  precipitate  of  sulphur  with  sulphuretted  hydrogen. 
Mixed  with  water  and  chloride  of  barium,  and  filtered  from  any  sulphate 
of  baryta  that  may  be  precipitated,  it  yields  a  fresh  precipitate  when 
boiled  with  nitric  acid. 

Sulphuric  acid:    Precipitates  chloride  of  barium,  after  dilution. 

Chlorine:  When  the  oil  of  vitriol  contains  nitric  acid  or  the  common 
salt  is  contaminated  with  a  nitrate.  Yellow  colour ;  odour ;  precipitation 
of  sulphur  from  hydrosulphuric  acid;  solution  of  gold  leaf;  bleaching 
of  solution  of  indigo. 

Nitrous  acid:  from  the  same  sources.  Test  with  oil  of  yitriol  and 
solution  of  ferrous  sulphate  (p.  181). 

Chloride  of  arsenic:  from  arsenic  contained  in  the  sulphuric  aoid 
employed. 

Wackenroder  (Eepert,  46,  225 ;  47,  337^  found  in  a  specimen  of  com- 
mercial hydrochloric  acid,  ■  ^ j^^  of  metallic  arsenic;  Dupasquier  (J. 
Pharm.  27,717)  YTJj'y  Wittstein  {ReperL  72,323),  yl^^;  andReinsch 
{J.  pr,  Chem,  24,  244),  as  much  even  as  ^j.  The  arsenic  is  doubtless 
present  in  the  acid  in  the  very  volatile  K>rm  of  chloride  of  arsenic. 
(Dupasquier.)  Hence  when  hyarochloric  acid  is  prepared  from  common 
salt  and  sulphuric  acid  containing  arsenic,  in  the  above-described  Woulfe's 
apparatus,  even  the  hydrochloric  acid  in  the  second  bottle  c  will  be  found 
to  contain  arsenic,  unless  the  first  bent  tube  is  made  to  dip  under  the 
water  in  the  first  bottle  h,  (Wackenroder.)  Even  when  commercial 
hydrochloric  acid  contaminated  with  arsenic  is  heated  in  a  retort  con- 
nected with  an  empty  tubulated  receiver,  from  which  a  bent  tube  conveys 
the  hydrochloric  acid  gas  into  water,  the  aqueous  acid  obtained  is  still 
found  to  contain  arsenic.  (Dupasquier.)  A rseniuietted  hydrochloric  acid 
yields  arsenical  spots  with  Marsh's  apparatus ;  covers  mercury  with  a 
brown  film  (Wittstein) ;  leaves  a  residue  of  arsenic  acid  when  evaporated 
to  dryness  with  nitric  acid,  though  when  evaporated  alone  it  leaves  no 
residue  (Dupasquier);  and  yields  yellow  fiakes  of  sulphide  of  arsenic,  when 
treated  with  hydrosulphuric  acid.  If  the  arsenic  be  precipitated  by  sul- 
phuretted hydrogen  and  the  acid  distilled  without  removing  the  precipitate, 
the  distillate  still  contains  arsenic,  because,  on  applying  heat,  tne  sulphide 
of  arsenic  is  again  decomposed  by  the  coucentrated  hydrochloric  acid. 
(Dupasquier.)  For  this  reason,  the  hydrochloric  acid  must  he  filtered  through 
asbestos,  after  the  arsenic  has  been  completely  precipitated  by  sulphuretted 
hydrogen  (Dupasquier)— or  diluted  with  an  equal  volume  of  water,  before 
being  treated  with  sulphuretted  hydrogen,  and  afterwards  filtered  through 
paper.  (Wackenroder,  Dupasquier.)  From  the  paper,  however,  the  acid 
takes  up  organic  matter,  which  imparts  a  yellow  colour  to  it  on  boiling, 
and  must  ^terwards  be  separated  by  distillation.  (Wittstein.)  It  is 
better,  therefore,  in  the  preparation  of  hydrochloric  acid,  to  employ  sul- 
phuric acid  free  from  arsenic. 

Bichloride  of  Tin :  passes  at  the  commencement  of  the  distillation  into 

Y  2 


324 


CHLORINE. 


the  first  Woulfe  8  bottle,  if  the  oil  of  vitriol  contaiiis  binoxide  of  tin. 
Hydrochloric  acid  which  contains  this  impurity  gives  with  hjdrosnl- 
phnric  acid,  after  several  days,  a  brown  precipitate  which  yields  a  globule 
of  tin  before  the  blowpipe.  (Berzelius,  Pogg,  83^  24.) 

Soda,  Lime,  and  other  faced  stibstances  remain  behind  when  the  hydro- 
chloric acid  is  evaporated  to  dryness. 

Aqueous  hydrochloric  acid  is  colourless,  when  perfectly  free  from  sea- 
quioxide  of  iron,  chlorine,  or  organic  matter ;  but  either  of  these  impuri- 
ties imparts  a  yellow  colour  to  it.  At  a  temperature  below  the  freezing 
point  of  mercury,  it  solidifies  to  a  mass  of  the  consistence  of  butter. 

Refractive  power  of  Aqueoiu  Hydrochloric  acid  of  different  densUiea; 
ihatof  Water  =  1. 

Sp.  gr.  Rcinct.  power.  Sp.  gr.         Refract,  power. 

1055  1-053  1-121  1121 

1-087  1-088  1146  M38 

1-177  1180 

Hence  the  refractive  power  of  the  acid  varies  directly  as  its  density. 
(Crighton,  Quart.  J.  of  Sc,  17,  182;  also  Schw.  32,  328.)  The  ooncen- 
trat^  acid  fumes  in  the  air ;  boils  at  a  temperature  which  is  lower  as 
the  strength  is  greater,  and  gives  off  a  portion  of  its  hydrochloric  acid 
gas;  a  more  dilate  acid,  on  the  contrary,  boils  at  a  higher  temperature 
than  water.  A  strong  acid  is  rendered  weaker  by  boiling,  a  weak  acid 
stronger,  so  that  the  ultimate  residue  is  of  the  same  strength  in  both 
cajses.  (Dalton.)  Hydrochloric  acid,  saturated  at  0*^  has  a  specific 
gravity  of  1-2109,  and  appears  to  contain  one  atom  of  hydrochloric 
acid  to  6  atoms  of  water  =  6H0,  HCl.  (Kane.)  The  acid  whose  boiling 
point  is  constant,  contains  20  per  cent,  of  hydrochloric  acid  gas,  and  con- 
sequently one  atom  of  acid  to  16  atoms  of  water.  The  specific  gravity 
of  its  vapour  is  0*691;  consequently  9  volumes  are  composed  of  one 
volume  of  hydrochloric  acid  gas  and  8  volumes  of  aqueous  vapour  united 
without  condensation.  (Bineau,  Ann.  Ckim,  Phys.  68,  422.)  Aqueous 
hydrochloric  acid  ha^  a  very  sour  taste,  and  a  slight  corrosive  action. 
It  has  a  pungent  and  purely  acid  odour,  but  when  contaminated  with 


iron,  it  smells  like  saffron 


Aqueous  hydrochloric  acid  is  miscible  with  peroxide  of  hydrogen,  and 
absorbs  carbonic  acid  gas  in  small  quantity. 

Percentage  of  Hydrochloric  Acid  Ooi  in  Aqueous  Hydrochloric  Acid, 


Davy,at25*'(77*»F.) 

According  to  Kirwan  &  Dalton. 

Sp.gr. 

Add 
percent. 

«     «.        Add 
^P-8'-    percent. 

Sp.gr. 

Add 
percent. 

Boiling 
point. 

1-21  . 

..  42-43 

Ill  ....  22.22 

1-199  ... 

3401  .... 

....     49**? 

1-20  . 

..  40-80 

110  ....  20-20 

1-181  ... 

31-09  .... 

....     65 

119  . 

..  38-38 

1-09  ....  18-18 

1-166  ... 

28-29  .... 

....     76 

118  . 

..  36-36 

108  ....  1616 

1-154  ... 

....  26-57  .... 

....     87 

117  . 

..  34-34 

107  ....  14-14        1 

1-144  ... 

....  24-84  .... 

....  100 

116  .. 

..  32-32 

106  ....  12-12        , 

1136  ... 

....  23-25  .... 

....  103 

1-15  .. 

..  30-30 

1-05  ....  1010 

1-127  ... 

....  21  06  .... 

....  105 

1-14  .. 

..  28-28 

1-04  ....     8-08 

1121  ... 

....  2074  . .. 

...  109 

1-13  .. 

..  26-26 

103  ....     606 

1-094  .... 

....  1608  .... 

...  Ill 

1-12  .. 

.  24-24 

102  ....     404 

1-075  .... 

....  13-16  .... 

...  109 

101  ....     202 

1-064  .... 

....  11-16  .... 

...  107 

1-047  .... 

....     8-62  .... 

...  105 

1-035  .... 

....     6-92  .... 

...  104 

1-018  .... 

....     3-52  

...  102 

1-009  .... 

....     1-86  

...  101 

fiYDROCULORIC  ACID. 


325 


Percentage  of  Hydrochloric  Acid  Gas  in  AqueouB  Eydrochloric  Acid. 


Aoooraing 

toA.  Ure 

{Dietumary  qf  Practical  ChemUtty,  99.) 

Sp.gr. 

Percent. 

Sp.gr. 

Percent. 

Sp.gr. 

Percent. 

Sp.gr. 

Percent. 

1.2000 

...  40-777 

11515  .. 

..  30*582 

1-1000  . 

...  20-288 

1-0497  ... 

.  10194 

M982 

...  40-369 

11494  . 

..  30-174 

1-0980  . 

...  19-980 

1-0477  ... 

9-768 

11964 

...  39-961 

1-1473  .. 

..  29-767 

1-0960  . 

...  19-572 

1-0457  ... 

9-379 

1-1946 

...  39-554 

1-1452  .. 

..  29-359 

1-0939  . 

...  19165 

1-0437  ... 

8-971 

11 928 

...  39-146 

11431  .. 

..  28-951 

1-0919  . 

...  18-757 

1-0417  ... 

8-563 

11910 

...  38-738 

1-1410  .. 

..  28-544 

1-0899  . 

...  18-349 

1  0397  ... 

8155 

11893 

...  38-330 

11389  .. 

..  28*136 

10879  . 

...  17-941 

1-0377  ... 

7-747 

11875 

...  37-923 

11369  .. 

..  27-728 

1-0859  . 

...  17-534 

1-0357  ... 

7-340 

11859 

...  37-516 

1-1349  .. 

..  27-321 

1-0838  . 

..  17126 

1-0337  ... 

6-932 

1-1846 

...  37-108 

1-1328  .. 

..  26-913 

1-0818  . 

...  16-718 

1-0318  ... 

6-524 

1-1822 

...  36-700 

1-1308  .. 

..  26-505 

1-0798  . 

..  16-310 

1-0298  ... 

6116 

1-1802 

...  36-292 

11287  .. 

..  26098 

1-0778  . 

..  15-902 

10279  ... 

6-709 

11782  , 

...  35-884 

1-1267  .. 

..  25-690 

10758  . 

..  15-494 

10259  ... 

5-301 

1-1762  . 

...  35-476 

11247  .. 

..  25-282 

1-0738  . 

..  15087 

10239  ... 

4*893 

1-1741  . 

...  35068 

1-1226  .. 

..  24-874 

10718  . 

..  14-679 

1-0220  .... 

4-486 

1-1721  . 

...  34-660 

1-1206  .. 

..  24-446 

10697  . 

..  14-271 

1-0200  .... 

4078 

11701  . 

...  34-252 

1-1185  .. 

..  24058 

10677  . 

..  13-363 

1-0180  ... 

3-670 

1-1681  . 

...  33-845 

1-1164  .. 

..  23-650 

1-0657  . 

..  13-456 

1-0160  ..., 

3-262 

1-1661  . 

...  33-437 

1-1143  .. 

..  23-242 

10637  . 

..  13-049 

1-0140  ... 

2-854 

1-1641  . 

...  33-029 

11123  .. 

..  22-834 

1-0617  . 

..  12-641 

10120  ... 

2-447 

1-1620  . 

...  32-621 

1-1102  .. 

..  22-426 

1-0597  . 

..  12-233 

1-0100  ... 

2039 

1-1599  . 

...  32-213 

1-1082  .. 

..  22-019 

1-0577  . 

..  11-825 

1-0080  ... 

1-631 

1-1578  . 

...  31-805 

11061  .. 

..  21-611 

10557  . 

...  11-418 

1-0060  ... 

1-224 

1-1557  . 

...  31-398 

11041  .. 

..  21-203 

10537  . 

...  11-010 

1-0040  ... 

0-816 

1-1536  . 

...  30-990 

11020  .. 

..  20-796 

10517  . 

...  10-602 

1-0020  ... 

0-408 

b.  With  Salifiable  bases.     EydrochlaraJtee.  (Vid.  Metallic  Chlorides,) 

c.  With  Organic  compounds^  as  with  alcohol,  volatile  oils,  &c. 

Bichloride  of  Htdrogek.  Concentrated  hydrochloric  acid  treated 
with  peroxide  of  lead  at  ordinary  temperatures,  yields  chloride  of  lead, 
water,  and  free  chlorine. 

PbO«  +  2HC1  «  PbCl  +  2H0  +  CI. 
But  if  the  peroxide  is  added  in  small  successire  portions  to  hydrochloric 
acid  contained  in  a  thin  tube,  and  surrounded  with  a  freezing  mixture, 
chloride  of  lead  is  precipitated  without  effervescence,  and  a  yellow  liquid 
obtained  which  probably  contains  bichloride  of  hydrogen. 

PbO*  +  3HC1  PbCl  +  2H0  +  HC1«. 
The  liquid  if  left  to  itself,  continues  to  evolve  chlorine  for  several  days ; 
with  zmc  or  mercury  it  jrields  chloride  of  the  metal  and  free  hydrochloric 
acid ;  it  exhibits  bleaching  jproperties,  and  disengages  carbonic  acid  gsus 
when  treated  with  oxalic  acid.  The  liquid  however  contains  lead  in 
solution,  which,  on  the  addition  of  water,  separates  in  the  form  of  peroxide; 
hence  it  probably  contains  PbCl*.  (Millon,  J.  Fharm.  28,  299.) — [May 
not  the  liquid  contain  hypochlorite  of  lead  1] 

2PbO«  +  2HC1«  Pba  +  2H0  +  PbO,C10.    (Gm.) 


326  CHLORINE. 


Chlorine  and  Cabbon. 


Cbareoal,  eyen  at  a  red  beat,  has  no  action  on  chlorine,  except  indeed 
that  a  email  qaantitj  of  hydrochloric  acid  it  at  first  produced  from  the 
hydrogen  contained  in  the  charcoal.  (Gay-Lnssac,  Th^nard,  H.  Davy.) 

CMoride  of  Carbon  and  Oil  ofOlefiant  Ocu  will  be  described  among 
Organic  Compoundi. 


Phosgene.    COCl. 

Chhrocarbonic  oxide,  Chlor-kohlenoxyd,  Adde  ehloroxyearhonique,'  Phoi- 
gene  gas,  Oas  c/Uoroxycarbonique. 

Formatum  and  Preparation,  —  1.  When  chlorine  gas  and  carbonic 
oxide,  both  perfectly  drjr,  are  mixed  in  an  exhausted  receiver,  no  action 
takes  place  in  the  dark;  but  in  diffused  daylight,  combination  ensnes 
in  the  course  of  24  hours,  and  in  sunshine  in  a  few  minutes,  a  new 
gas  being  formed  which  occupies  half  the  volume  of  the  original  mixture. 
(J.  Davy.) — 2.  Carbonic  oxide  gas  passed  over  ignited  chloride  of  lead  or 
chloride  of  silver,  reduces  the  metal  and  yields  phosgene  gas.  (Gobel, 
J,  pr.  Chem,  6,  388.) 

Froperties,  Colourless  gas  (for  the  specific  gravity  and  refractive 
power,  vid.  p.  279);  does  not  fume  in  the  air;  has  a  more  unpleasant 
and  suffocating  odour,  even  than  chlorine  gas;  excites  tears;  reddens 
moistened  litmus-paper.  (J.  Davy.) 

Calcolation,  iccording  to  J.  Davy.  Volume.        Sp.  gr. 

CO 14-0  28-34  Carbonic  oxide  gas 1  0*9706 

CI   35*4  71-66  Chlonnegas    1  2*4543 

CO,  CI....  49-4  10000  Phoigene  gas   1  3*4249 

(CO,  Cl«  =  176-44  +  2  .  221-33  =  61910.     BerzeUns.) 

This  compound  cannot  well  be  regarded  as  carbonic  acid  in  which 
1  At.  0  is  replaced  by  1  At.  CI,  inasmuch  as  1  volume  of  phosgene  gas 
condenses  2  volumes  of  ammouiacal  gas,  whereas  1  volume  of  carbonic  acid 
ffas  condenses  at  most  1  volume  of  ammoniacal  gas ;  it  is  probably  there- 
fore carbonate  of  bichloride  of  carbon  =  CO',CCP.  (H.  Hose,  Fogg,  52, 
77.)  On  the  other  hand,  however,  it  must  be  observed  that  the  com- 
pound CCP  is  not  known  to  exist.  [It  has  since  been  discovered  by 
Regnault  (W.)  ]. 

Decompositions, — 1.  Cannot  be  made  to  explode  by  the  electric  spark 
when  mixed  either  with  oxygen  or  with  hydrogen  gas  alone  ;  but  if  mixed 
at  the  same  time  with  half  its  volume  of  oxygen  and  an  equal  volume  of 
hydrogen,  it  explodes  violently  by  the  electric  spark,  yielding  hydro- 
chloric acid  and  carbonic  acid.  Water  rapidly  produces  the  same  decomo 
position  (slowly,  however,  according  to  Serullas,  Ann.  Chim,  Fhys.  28, 
187). — 2.  Potassium  causes  the  entire  disappearance  of  the  gas,  one 
portion  of  the  metal  absorbing  the  chlorine,  and  another  portion  the 
oxyffen  of  the  carbonic  oxide,  without  evolution  of  light  or  heat:  the 
products  are  chloride  of  potassium,  potash,  and  carbon. — 3.  Arsenic, 
antimony,  zinc,  and  tin,   when  introduced  into  the  gas  in   a  heated 


CHLORIDE  OF  BORON.  327 

state^  are  Gonverted,  without  incandescence^  into  chlorides^  and  a  quan- 
tity of  carbonic  oxide  gas  is  separated  equal  in  volume  to  the  decom- 
posed phosgene. — 4.  Oxide  of  zinc  heated  in  phosgene  gas,  removes  the 
chlorine  from  the  carbonic  oxide,  and  replaces  it  with  its  own  oxygen, 
forming  chloride  of  zinc  and  carbonic  acid  gas^  of  the  same  volume 
as  the  original  phosgene.  Oxide  of  antimony  produces  chloride  of  anti- 
mony and  antimonious  or  antimonic  acid,  and  leaves  carbonic  oxide  gas. 
Phosphorus  and  sulphur  sublimed  in  phosgene  gaa,  do  not  produce  any 
change.  (J.  Davy.) 

ComhincUions,     a.  With  chloride  of  sulphur.— 6.  With  ammonia.— » 
<;.  With  chloride  of  arsenic— (^.  With  alcohol. 


Ghlorinb  Atfv  Boron. 

Ghlobidb  of  Boron.    BCl*. 

Ohlorbaron,  CMorure  de  Bore;  in  the  gaseous  form:  Chloroborto 
gas. 

Formation, — 1.  Recently  prepared  boron^  not  previously  heated  in 
vacuo,  takes  fire  spontaneously  in  chlorine  eas^  and  bums  with  great 
splendour ;  after  being  heated,  however^  it  in&mes  at  high  temperatures 
only.  (Berzelius.) — 2.  Chlorine  gas  brought  in  contact  with  an  ignited 
mixture  of  charcoal  and  boracio  acid,  forms  chloride  of  boron  and  carbonio 
oxide.  (Dumas.) 

BO»  +  3C  +  3CT  »  Ba»  +  SCO. 

The  resulting  gaseous  mixture  contains  8  volumes  of  carbonio  oxide  to  2 
volumes  of  chloride  of  boron.  (Dumas.) 

Preparation, — 1.  Dry  chlorine  gas  is  passed  over  perfectly  dry  boron 
ignited  in  the  broad  part  of  a  tube;  the  gas  is  collected  over  mercury;  and 
the  free  chlorine  removed  by  agitation  with  the  mercury.  (Berzehu8.)«« 
2.  A  mixture  of  charcoal  and  boracic  acid  is  ignited  in  a  glass  or  porce- 
lain tube  for  an  hour,  in  order  to  expel  every  trace  of  moisture,  and  per- 
fectly dry  chlorine  afterwards  passed  over  the  ignited  mixture.  Even 
(he  stoppers  must  be  perfectly  dry;  if  any  moisture  is  present,  hydro- 
chloric acid  is  formed,  and  boracic  acid  deposited  in  the  tube.  (Dumas.) 
From  the  gaseous  mixture  collected  over  mercury,  the  oarbonio  oxide 
cannot  be  removed. 

Properties,  Colourless  gas,  having  a  sour,  pungent  odour  arising  from 
the  formation  of  hydrochloric  acid ;  emits  dense  white  fumes  in  the  air 
as  abundantly  as  gaseous  fluoride  of  boron.  (Berzelius.) 

CalcnlAtioii.  Vol.      Sp.gr.        Vol.        Sp.gr. 

B 10-8....     9-23      Vapour  of  Boron? 1  ....  0-7487    =     §    ....0-3743 

3C1    ....  106-2  ....  90-77      Chlorine  gaa 3  ....  73629    =     Ij  ....  3-6815 

BCP    ....  117.0  ....100-00       ChlopboMcicaddgaa.  2  ....  81116    =*     1     ....4-0558 
(BC1«  =  136-2  +  6  .  221-33  «  146418.    Berxdina.) 

The  gas  is  rapidly  but  not  instantaneously  absorbed  by  water,  which 
converts  it  into  hydmchlorio  and  boracic  acids ;  when  a  small  quantity  of 
water  is  used,  the  latter  is  deposited  on  the  sur&ee  in  the  8<Aid  form. 


328  CHLORINE. 

(BerzelioB.)  With  a  small  quantity  of  water,  chloride  of  boron  forms  a 
solid  hydrate,  which,  at  a  low  red  heat  is  decomposed  by  hydrogen  gas 
into  hydrochloric  acid  and  boron.  (Damas;  camp.  Liebig,  Schw,  47,  117.) 
Chloride  of  boron  combines  with  ammonia,  and  is  likewise  absorbed  by 
alcohol.  (Berzelius.) 


Chlorine  and  Phosphobus. 

A.    Terchloridb  of  Phosphorus.    PCI'. 

DreifacMdorphoiphor,  Chlorphotphor   im  Minimum,  Protocklorure    de 

Fhosphore, 

Formation.  1.  Phosphorus  takes  fire  in  chlorine  gas  at  ordinary  tem- 
peratures, burning  with  a  pale  green  light  and  emission  of  sparks,  and 
forming  terchloride  or  pentachloride  of  phosphorus,  according  to  the  pro- 
portions in  which  the  two  elements  are  brought  together. — 2.  Phosphorns 
withdraws  chlorine  from  mercurj. — 3.  Terchloride  of  phosphorus  appears 
also  to  be  formed  in  small  quantity,  when  glacial  phosphoric  acid  is  ignited 
with  common  salt.  (Gay-Lussac  8c  Th§nard.) 

Preparation.  Chlorine  gas  slowly  evolved  in  the  flask  a  (App.  52), 
is  made  to  pass,  first  into  an  empty  bottle  b,  artificially  cooled,  then 
through  a  tube  c  filled  with  chloride  of  calcium,  and  lastly,  into  the  tubu- 
lated retort  d,  from  which  the  terchloride,  as  it  forms,  distils  over  into  the 
iteceiVer  e. — 2.  Vapour  of  phosphorus  is  passed  over  heated  dichloride  or 
protochloride  of  mercury.  Phosphorus  is  placed  at  the  closed  end  of  a 
tube,  chloride  of  mercury  in  the  middle,  and  the  open  end  of  the  tube  is 
connected  with  a  receiver  kept  at  a  low  temperature.  (H.  Davy.)  Ac- 
cording to  Berzelius  and  Dulong,  the  compound,  as  obtained  by  either  of 
the  preceding  methods,  may  be  purified  from  excess  of  phosphorus  by  a 
second  distillation ;  according  to  Davy,  however,  the  purification  thus  at- 
tained is  not  complete. 

Properties.  Transparent  and  colourless ;  very  fluid ;  specific  gravity 
=  1-45.  (H.  Davy.)  Boils  at  78°  (172-4  F.)  when  the  barometer  stands 
at  30  inches  (Dumas);  at  78*34°  (173"*  F.)  when  the  barometer  stands  at 
29-83  inches.  (Pierre.)  Specific  gravity  of  the  vapour  {!.,  279).  Does 
not  conduct  electricity.  Forms  white  fumes  in  the  air ;  has  a  pungent 
odour,  like  that  of  hydrochloric  acid;  does  not  redden  dry  litmus  paper. 
(H.  Davy.) 

Calculation.  H.  Davjr.  Berzelina. 

earlier.  later. 

P  31-4  22-82     23  26-3  23 

301  106-2  77-18    77  73-7  77 


PC1».... 

....  137-6  

.100-00     . 

100  

..100-0 

...100 

Vapotir 
Chlorine 

of  phosphoruB 

'gM      

Vol. 

1  . 

6  . 

Sp.gr. 
...  4-3539 
...14-7258 

__ 

Vol. 

Sp.gr. 
..  10885 
..  3-6814 

Vaponr  of  terchloride  of  phosphorus    4  ....19-0797       =       1    ....  4*7699 
(PCP  =  196-14  +  3  .  221-33  «  86013.    BerxeUua.) 

Decompontions. — 1.  The  vapour  bums  in  the  fiame  of  a  candle.  (H. 


PENTACHLORIDE  OF  PHOSPHORUS.  329 

Davy.) — 2.  With  water,  it  gradually  forms  hydrochloric  and  phosphorous 
acid,  the  decomposition  being  attended  with  rise  of  temperature.  (H. 
Davy.) 

PCP  +  3H0  =  P03  +  3HC1. 

3.  Iron  filings  brought  in  contact  with  it  at  a  red  heat  produce  chloride  and 
phosphide  of  iron.  (Gay-Lussac  &  Thenard.)  Potassium  bums  in  its 
vapour  with  a  dazzling  light.  (H.  Davy.) — 4.  With  phosphuretted  hy- 
drogen gas,  it  forms  hydrochloric  acid  and  yellow  phosphorus,  which  soon 
turns  T&d  on  exposure  to  light.  (H.  Rose,  Pogg.  24,  307.) 

PCP  +  PH'  =  3HC1  +  2P. 
Similarly  with  hydrosulphuric  acid  gas,  it  forms  hydrochloric  acid  and 
tersulphide  of  phosphorus,  with  evolution  of  heat.  (Serullas,  Ann.  Ckim, 
Phys.  42,  32.) 

PCI  +  3HS  =  PS»  +  3HC1. 

Terchloride  of  phosphorus  when  heated  is  capable  of  dissolving  a 
small  additional  quantity  of  phosphorus.  The  solution,  when  exposed  to 
the  air,  deposits  a  film  of  phosphorus;  paper  moistened  with  it  takes  fire  as 
soon  as  the  liquid  has  evaporated  by  exposure  to  the  air.  (H.  Davy.) 
The  solution  remains  clear  in  the  dark,  but  deposits  hydrated  phosphoric 
oxide  when  exposed  to  daylight;  in  direct  sunshine  the  red  oxide  is 
cjuickly  deposited.  (Leverrier,  Afin.  Chim,  Phys.  65,  259.)  With  water 
it  forms  hydrochloric  and  phosphorous  acid,  and  deposits  colourless,  trans- 
parent phosphorus,  which  obstinately  retains  chlorine.  (Berzelius.) 

Terchloride  of  phosphorus  combines  with  ammonia. 

B.     Pentachlortde  of  Phosphorus.     PCP. 

Funfdch'chlorphosphor,   CJdorphosphor  im  maximum,  DetUochlorure  dc 

Phosphore. 

Formation  and  Preparation, — 1.  By  burning  phosphorus  in  excess  of 
dry  chlorine  gas — most  conveniently,  in  a  Woulfe*s  bottle  or  a  tubulated 
retort  {App,  52)  not  heated. — 2.  By  exposing  terchloride  of  phosphorus 
to  chlorine  gas. 

Properties,  Snow-white  powder,  which  volatilizes  much  below  100®; 
may  be  fused  under  increased  pressure ;  and  afterwards,  on  cooling,  crys- 
talfizes  in  transparent  prisms.  Does  not  conduct  electricity.  Fumes  in 
the  air ;  reddens  dry  litmus  paper.  (H.  Davy.^  Berzelius  attributes  this 
effect  to  the  formation  of  hydrochloric  and  pnosphoric  acid  by  the  com- 
bination of  the  phosphorus  with  the  hydrogen  and  oxygen  of  the  paper. 

Calculatioii.  H.  Davy,        Dnlong.  Berzelius. 

P   31-4  1507  13  15-4  1531 

5C1  177-0  84-93  87  84-6  84-69 

~~PCl*    208-4  10000  100  lOO'O  lOO'OO 

Vol.         8p.gr.  Vol.       Sp.gr. 

Vapour  of  phosphorus  1  ....     4*3539       =       i  ....  0'7256 

Chlorine  gas  10  ....  24*5430       =       ]  ....  4*0905 

Vapour  of  pentachloride  of  phosphorus      6  ....  28*8969       «       1  ....  4*8161 
(Pa»  =:  196-14  +  5  .  221*33  =  1302- 79.    Berzdius.) 

Decompoiitione, — 1 .  Begins  to  bum  when  put  into  the  flame  of  a  candle. 


^30  CHLORIKB. 

On  paasing  it0  vapour  mixed  witli  ozjen  gas  throngli  a  red-hot  por- 
eelain  tube,  phoaphoric  acid  and  chlorine  gas  are  obtained.  (H.  Davy.)-^ 
2.  With  water  it  forms  phosphoric  and  hydrochloric  acid^  great  heat  being 
evolved.  (H.  Davy.)  Sch.  40: 

PC1»  +  5HO  «  PO»  +  6HCL 

-r-Z,  Pentachloride  of  phosphorus  and  phospharetted  hydrogen  form  hydro- 
chloric acid  and  terchloride  of  phosphorus,  or  hydrochloric  acid  and  phoe- 
phorus,  according  as  the  quantity  of  the  latter  compound  is  smaller  or 
greater; 

3PC1»  +  PH»  =  4Pa»  +  3HCI 
and:       3PCl*+    5PH'  =»  8P  +  15HCL 

*->4.  With  dry  hydrosulphurio  acid  ras,  the  products  aie  hydroohlorio  aoid 
and  chloroeulphide  of  phosphorus.  (SeruUas.) 

PCl»  +  2HS  =  PS«a»  +  2HC1. 
—5.  Potassium  heated  in  its  vapour  bums  with  great  rapidity  and  bril- 
liancy. (H.  Davv.)— ^.  With  metallic  oxides,  it  forms  chloride  of  the 
metal  and  phosphate  of  the  oxide.  (H.  Davy.) 

Pentachloride  of  phosphorus  forms  a  definite  compound  with  am- 
monia. 

IT      C.      OXTCHLORIDE  OP  PHOSPHORUS.      PCPO*. 

Formation  and  Preparation.     When  pentachloride  of  phosphorus  is 
leffc  to  stand  in  an  imperfectly  stopped  bottle  or  a  long>necked  flask,  in 
which  is  also  placed  a  tube  filled  with  water,  it  fi:radnally  liquefies  and 
evolves  a  considerable  quantity  of  hydrochloric  acid : 
PC1»  +  2HO  =  PCI*  01  +  2HC1. 

On  distilling  tho  product  after  all  the  pentachloride  has  disappeared, 
the  hydrochloric  acia  passes  over  first,  and  afterwards,  when  the  tem- 
perature reaches  110''  (230*"  F.),  the  oxychloride. 

Properties.  Colourless  liquid,  of  high  refracting  power,  and  having  a 
pungent  odour  like  that  of  terchloride  of  phosphorus.  Specific  gravity 
=  1  *?,  at  the  temperature  of  12""  (53  6*'  F.).  Specific  gravity  of  the  vapour 
5-4. 

Calculation.  Warts. 

P 31'4  20*44  20-50 

3C1    ....  106-2  6914  68-95 

20  16-0  10-42  10-55 

PCPO«        153-6  100-00  10000 

Vol.  Sp.gr.  Vol.      Sp.gr. 

Vapour  of  phosphorns  1  ....  4*3539  «  \  ....  1*0885 

Chlorine  gas  6  ....  14-7258  «  \\  ....  3-6814 

Oxygen  gas   2  ....  22186  ^  \  ....  0*5546 

Vapour  of  oxychloride  of  phosphorus  ....  4  ....  21-2983      =     1     ....5-3245 
(PC1=»0  =  196-14  +  3  .  221-33  +  100  =  96013.    BeneUus.) 

Oxychloride  of  phosphorus  emits  white  fumes  when  exposed  to  the  air; 
it  is  decomposed  by  water,  the  products  being  phosphoric  and  hydro- 
chloric acid,  (reciprocal  affinity): 

PC1»0«  +  3HO  =  PO»  +  3Ha. 

Not  decomposed  by  hydrosulphuric  acid.  Forms  a  white  solid  compound 
with  ammonia.  (Wurtz.  N.  Ann.  Chim.  Phy$,  20,  472.)  IT 


CHLORIDE  OP  SULPHUR.  S31 

Hydrochlorate  of  Phosphttretted  Hydrogen.  Known  in  union 
with  the  compound  of  chloride  of  titanium  and  phosphnretted  hydrogen. 
Hydrochloric  acid  gaa  and  phosphu retted  hydrogen  gas  do  not  act  on  each 
other  perceptibly,  even  in  sunshine ;  moreover,  the  hydrochlorio  iu;id 
may  be  absorbed  from  the  mixture  by  water  and  even  by  borax.  But 
when  a  mixture  of  these  two  gases,  prepared  with  the  less  inflammable 
phosphuretted  hydrogen,  is  passed  through  aqueous  ammonia,  the  unab- 
sorbed  gas  is  found  to  be  spontaneously  inflammable  (H.  Rose).  This 
circumstance  is  in  favour  of  the  supposition  that  the  gases  are  really 
combined,  but  without  condensation,  just  as  hydriodic  and  hydrobromic 
acid  combine  with  phosphuretted  hydrogen  without  condensation.  The 
diflference  between  them  is  that  the  hydrochloric  acid  compound  is  much 
more  elastic,  not  undergoing  liquefaction  even  at— 12°.  (Bineau,  Ann^ 
Chim.  Fhyt.  68,  431.) 

Chlorine  and  Sulphur. 
A.  Chloride  of  Sulphur. 

Stdpho-muriatio  acid,  ChlorBchwefel,  SchwefeUdluaure  Sdlzsaurn 
Sckweftloxyd^  Chlorure  de  Soufre, — FormcUion.  Pounded  sulphur  absorbs 
chlorine  gas  even  at  ordinary  temperatures,  the  combination  being 
attended  with  development  of  heat:  the  absorption  is  accelerated  by 
subliming  the  sulphur  in  the  gas.  Berthollet's  statement,  that  burning 
sulphur  continues  to  burn  when  immersed  in  chlorine  gas,  appears  to  be 
unfounded. 

a.      DiCHLORIDB  OF  SuLPHUR.      S^Cl. 

IfaUhcIUorschwefel,  Ohlanchwefel  im  Minimum,  Frotochlorure  de  Soufre* 

Preparation.  Dry  chlorine  gas  is  passed  through  washed  and  dried 
flowers  of  sulphur,  till  the  sulphur  is  neally  all  dissolved.  The  liquid  is 
then  decanted,  and  freed  by  distillation  at  a  gentle  heat  from  the  excess 
of  sulphur  which  is  dissolved  in  it  (H.  Rose).  Dumas  rectifies  this  first 
distillate  a  second  time,  because  part  of  the  excess  of  sulphur  generally  passes 
over  with  it.  Marchand  repeats  the  rectification  till  the  boiling  point  of 
the  liquid  becomes  fixed  at  109''  (228*2''  F.).  For  passing  the  chlorine 
through  the  sulphur,  App.  52  may  be  used,  substituting  for  the  retort  d 
and  receiver  e,  two  Woulfe's  bottles  to  contain  the  sulphur,  these  bottles 
being  surrounded  with  cold  water  and  connected  by  a  bent  tube.—- 
^  2.  Chlorine  gas,  previously  washed  and  dried,  is  passed  into  a  tubu- 
lated retort  {App.  52)  in  which  sulphur  is  sublimed  by  the  application  of 
a  gentle  heat :  the  chloride  of  sulphur  distils  over  and  may  be  condensed 
in  a  receiver  surrounded  by  cold  water ;  it  must  afterwards  be  rectified  to 
free  it  from  excess  of  sulphur.  (Mitscherlich,  Lehrh,  I.,  67.)  IT— 3.  A  mix- 
ture of  ]  part  sulphur  with  9  parts  protochloride  of  tin,  or  8 '5  parts  proto- 
chloride  of  mercury  is  subjected  to  distillation.  (Berzelius.) 

Properties.  Brownish  yellow,  oily  liquid  of  specific  gravity  1'687 
(Dumas),  1*686  (Marchand).  Boils  at  138°  (280*4"  F.)  Dumas',  begins 
to  boil  at  134°,  but  the  boiling  point  soon  rises  to  139°,  and  then  remains 
constant.  (Marchand.)  Specific  gravity  of  the  vapour  (I.,  279).  Fumes 
strongly  in  the  air;  has  a  disagreeable,  sufibcating  odour,  something  like 
that  of  sea-weed;  its  vapour  excites  tears;  its  taste  is  sour,  hot,  and 
bitter.  Reddens  perfectly  dry  litmus  paper,  according  to  Davy;  accord- 
ing to  Martens,  it  does  not. 


332  CHLORINE. 

Damas^ 
Calculation.  Mardumd.     H.Rose.      Bacholz. 

2S  32-0  47-48  475  47-46  47*4 

CI   35-4  52-52  52-5  52*98  52-6 

S«C1 67-4  10000  100-0  10044  100*0 

Vol.       Sp.gr.  Vol.      Sp.gr. 

Vapour  of  sulphiir     1  ....  6-6556       =     )  ....  2'2185 

Chlorine  gaa  3  ....  7-3629      =      1  ....  24543 

Vapour  of  dichloride  of  sulphur    3  ....14*0185      «=      1  ....  4-6728 
rSCl  ==  20117  +  221-33  «=  422-50.    (B«rzelius.) 

Decamposiiions, — 1.  Dichloride  of  sulphar,  when  pat  into  water,  sinks 
to  the  bottom  in  the  form  of  oily  drops,  and  on  dotation,  is  rery  slowly 
decomposed,  yielding  hydrochloric  acid,  precipitated  sulphur,  and  hypo- 
sulphurous  acid — ^the  last  of  which  products  gradually  resolres  itself  into 
sulphurous  acid  and  sulphur  (Thomson)  : 

2S«C1  +  2H0  =  2HC1  +  SO«  +  38. 

A  small  quantity  of  sulphuric  acid  is  however  produced  at  the  same  time, 
even  if  the  chloride  still  contains  excess  of  sulphur.  (Bucholz,  H.  Rose.) 
Since  bichloride  of  sulphur  (as  obtained  in  combination  with  metallic 
chlorides)  is  resolved  by  water  into  hyposulphurous  and  sulphuric  acid,  it 
is  possible  that  the  dichloride  may  be  a  compound  of  the  bichloride  with  3 
atoms  of  sulphur,  S',  SCI*.  (H.  Rose.) — The  liquid  was  found  to  contain 
undecomposed  h3rposulphurou6  acid,  and  consequently  gave  a  black  pre- 
cipitate with  nitrate  of  silver,  even  ten  days  after  the  decomposition  by 
water.  The  separated  sulphur  amounts  to  27*74  parts  out  of  100  parts 
of  the  dichloride,  which  is  much  less  than  three-fourths  of  the  whole 
quantity  of  sulphur.  (H.Rose.) — 2.  Phosphorus  withdraws  chlorine  from 
sulphur,  producing  a  rise  of  temperature  of  40°,  so  that,  on  distilling  the 
liquid,  terchloride  of  phosphorus  passes  over,  while  sulphur  remains  be- 
hind. (Gaultierde  Claubry,  Ann.  Chim,  Phys,  7,  213.) — 3.  Hydrosulphuric 
acid  resolves  dichloride  of  sulphur  into  hydrochloric  acid  and  sulphur. 
(H.  Rose.) 

S*C1  +  HS  =  3S  +  HCl. 

— 4.  Vapour  of  oil  of  vitriol  and  vapour  of  dichloride  of  sulphur  passed 
through  a  red-hot  tube  yield  sulphur,  sulphurous  acid,  hydrosulphuric 
acid,  hydrochloric  acid,  and  chlorine.  (Brault  &  Poggiale,  J.  Pharm,  21, 
140.) — 5.  Dichloride  of  sulphur  dissolves  in  ether  when  first  mixed 
with  it,  but  is  afterwards  decomposed^  with  slight  evolution  of  heat. 
(Dumas.) 

Comhinaiiona, — a,  Dichloride  of  sulphur  dissolves  sulphur  in  larse 
quantity;  so  much  indeed  when  heated  as  to  form  a  syrup,  from  which, 
on  cooling,  sulphur  continues  to  separate  for  several  weeks.  When  satu- 
rated with  sulphur  at  ordinary  temperatures,  it  has  a  clear  yellow  colour, 
and  contains  altogether  66  74  p.  c.  sulphur  (H.  Rose);  consequently, 
about  4  At.  sulphur  to  1  At.  chlorine.  This  solution  has  a  specific  gra- 
vity of  1-7,  and  when  distilled,  leaves  the  excess  of  sulphur  behind;  when 
the  liquid  evaporates  gradually  in  the  air,  the  sulphur  which  separates 
has  a  ciystalline  character.  (Bucholz,  BerthoUet.) 

b.  Mixes  easily  with  bisulphide  of  carbon.  (A.  BerthoUet.) 

c.  Absorbs  phosgene  gas. 

d.  Combines  with  ammonia. 

t.  Combines  with  certain  metallic  chlorides.  (H.  Rose.) 


PROTOCHLORTDB  OP  SULPHUR,  835 

6.    Protochloride  op  Sulphur.    SCI. 

Einfach  Cklorschwefdy  DetUocMorure  de  Soufre. 

Preparation. — 1.  Dry  cblorine  gas  in  large  excess  is  passed  for  several 
days  through  flowers  of  sulphar;  the  liquid  distilled  between  60®  and  70^ 
(140°— 158®  F.);  and  the  distillate,  which  still  contains  a  little  dichloride 
of  snlphur,  again  distilled  several  times  in  a  stream  of  chlorine  gas,  at  a 
temperature  below  its  boiling  point.  (Damas;  Soubeiran,  Ann.  Chim. 
Phys.  67,  74.)  The  chlorine  is  admitted  during  the  distillation,  through 
the  tubulure  of  the  retort.  Even  when  chlorine  gas  is  passed  through 
sulphur  for  ten  hours,  the  proportion  of  sulphur  is  not  reduced  below  37*51 
per  cent. ;  if  a  small  portion  be  distilled  from  it,  the  distillate  is  found 
to  contain  dd'41  p.  c. ;  a  second  portion,  distilled  below  the  boiling  point, 
contains  32*55  p.  c.  of  sulphur,  and  therefore  approaches  nearly  to  SCI. 
(H.  Rose.)  Dichloride  of  sulphur  absorbs  chlorine  gas  slowly,  increasing 
considerably  in  volume  by  the  absorption  :  when  no  more  chlorine  is  abr 
sorbed,  even  after  the  passage  of  the  gas  has  been  continued  for  a  long  time, 
the  liquid  deposits  Millon*s  solid  protochloride  of  sulphur  {q.  v,)  and  at 
the  same  time  evolves  chlorine  continuously.  Its  specific  gravity  is  1  '625 ; 
it  boils  at  50®  at  first,  evolving  nearly  pure  chlorine ;  but  afterwards,  the 
boiling  point  rises  to  64®;  and  then  the  liquid  is  found  to  contain  31*73 
per  cent,  of  sulphur.  (Marchand.)  If  the  liquid  be  distilled,  after  thrice 
repeated  cohobation  (I.,  288)  till  it  no  longer  evolves  free  chlorine,  it  is 
found  to  boil  constantlv  at  78®  (140*4°  F.),  and  to  contain  37*78  per  cent, 
of  sulphur;  it  is  therefore  a  ^-Moride  of  sulphur,  S*C1'.  (Marchand.) 

Properties.  Dark,  brown- red,  thin  liquid,  of  specific  gravity  1*620; 
boils  at  64®  (147*2°  F.);  specific  gravity  of  the  vapour  =  3*7.  (Dumas.) 
Does  not  solidify  at  —  30°.  (H.  Rose.)  Fumes  and  smells  like  the  dichlo- 
ride, but  has  more  of  the  odour  of  chlorine  than  the  latter;  tastes  sour,  hot, 
and  bitter.  (Thomson.)  According  to  Martens  {J.  Chem.  Med,  13, 430),  it 
reddens  dry  litmus  paper  fully;  according  to  Davy,  it  does  not. 

H.  Davy.  Dumaa. 

Calculation.  earlier.  later. 

S  16  31*13       30  30-36  31*9 

CI  35*4  68*87       67  69*64  68-1 

S*C1  51*4  10000      100  100*00  100*0 

Vol.       Sp.gr.  Vol.      Sp.gr. 

Vaponr  of  sulphur 1  ....     6*6556      =      i  ....  1-1093 

Chlorine  gas        6  ....  14*7258      =      1  ....  24543 

Vapour  of  protochloride  of  rolpbur    6  ....  21*3814      =      1  ....  3-5656 
(SCI*  =  201*17  +  2*221-33  =  643*83.    Berzdius.) 

Decompositions. — According  to  Dumas,  protochloride  of  sulphur  evapo- 
rates as  a  whole  without  decomposition ;  but,  according  to  Marchand,  it 
begins  to  boil  at  50"^,  evolving  nearly  pure  chlorine  gas ;  afterwards  the 
boiling  point  rises  to  64®.  It  also  evolves  chlorine  when  exposed  to  sun- 
shine, and  with  sufficient  force  to  break  the  vessel  in  which  it  is  enclosed. 
— 2.  When  a  piece  of  potassium  is  dropt  into  about  half  a  gramme  of  this 
liquid,  a  red  li^ht  is  often  produced  after  about  40  seconds,  and  likewise 
an  explosion  which  bursts  the  vessel.  Vapour  of  protochloride  of  sul- 
phur passed  over  red-hot  iron  or  copper  filings  produces  a  chloride  and 


aS4  CHLORINR. 

Bnlphide  of  the  metal,  with  eyolution  of  light  and  hoit  (Damas.)— 3.  In 
contact  with  water,  protochloride  of  sulphur  is  slowly  decomposed,  the 
chief  products  heing  hydrochloric  and  hyposulphurons  acid,  which  latter 
is  further  resolved  into  sulphurous  acid  and  sulphur. 

2SC1  +  2HO  =  2HC1  +  S«0«; 
but,  according  to  Rose,  sulphuric  acid  is  produced  at  the  same  time. — 
4.  Nitric  acid  oonyerts  protochloride  of  sulphur,  with  violent  effervescence, 
into  hydrochloric  and  sulphuric  acid.  (Thomson.) — 5.  With  aqueous 
ammonia,  this  substance  forms  sulphur,  nitrogen  gas,  and  sal-ammoniac. 
n)umas.)  Its  relations  with  ammonia  will  be  given  under  the  heads  of 
Sulphide  of  Nitrogen  and  Nitrogen  and  Chlorine. — 6.  Froths  up  violently 
with  alcohol  (Thomson);  likewise  with  ether  (Dumas). 

Combinations. — a.  It  dissolves  phosphorus,  forming  an  amber-colonred 
solution.  (Thomson.) 

b.  Absorbs  phosgene  gas. 

e.  Dissolves  iodine,  forming  a  deep-red  liquid  which  does  not  conduct 
electricity.  TSolly,  Fogg.  37,  420.) 

d.  Combines  with  ammoniacal  gas.  (Soubeiran.) 

e.  Combines  with  chloride  of  arsenic.  (H.  Rose.) 

Solid  Protochloride  of  Sulphur.  When  chlorine  gas  is  passed  for  a 
long  time  through  liquid  protochloride  of  sulphur,  yellow  ciystals  are  pro- 
duced, having  the  odour  of  the  liquid  protochloride.  When  exposed  to 
the  air,  they  evaporate  quickly  and  completely  in  white  fumes ;  dissolve 
readily  in  dichloride  of  sulphur,  changing  its  yellow  colour  to  brownish 
red;  also  in  water,  with  loud  hissing  and  slight  deposition  of  sulphur. 
(Millon,  Compt.  Mend.  6,  207;  also  J.  pr.  Chem.  16,  57.)  The  same  crys- 
tals were  obtained  by  Marchand.  They  contain  30*93  per  cent,  of  sul- 
phur. When  they  dissolve  in  water,  hydrochloric,  sulphuric,  sulphurous 
and  hyposulphurons  acids  are  produced,  besides  precipitated  sulphur. 
Marchand  regards  them  as  pure  protochloride  of  sulphur,  and  the  liquid 
compound  ajs  containing  a  somewhat  larger  quantity  of  sulphur. 

c.  Bichloride  op  Sulphur. — Known  only  in  combination  with 
bichloride  of  titanium,  bichloride  of  tin,  or  pentachloride  of  antimony. 
Resolved  in  contact  with  water,  into  sulphuric  and  hyposulphurons  acid, 
the  latter  being  subsequently  converted  into  sulphurous  acid,  with  deposi- 
tion of  sulphur.  (H.  Rose,  Pogg.  42,  517.) 

d.  Terchloride  op  Sulphur. — May  be  obtained  in  combination 
with  sulphuric  acid. 

B.  Chlorgsulphibb  op  Phosphorus. 

a.  PS^oCl»,  or  PS*  -h  2S*C1.— When  phosphuretted  hydrogen  gas  is 
passed  into  dichloride  of  sulphur,  this  compound  is  formed  together  with 
nydrochlorio  acid. 

68*C1  +  PH3  ^  PS»»CP  +  3HC1. 

Yellowish,  very  tenacious  syrup. 

Calculation. 

P   31-4  11-98 

IDS  1600  6102 

2C1  70-8  2700 

PS'o,Cl« 262'2  100-00 


CHLOROSULPHIDE  OF  PHOSPHORUS.  335 

Does  not  ebange  under  water,  when  first  immersed,  but  afterwards 
becomes  white  on  the  surface  and  renders  the  water  milky,  from  separ 
ration  of  sulphur ;  likewise  imparts  to  it  a  powerful  odour  of  hvdrosul' 
phurio  acid,  in  consequence  of  the  phosphorus  absorbing  oxjgen  from  the 
water.  The  sulphur  separated  amounts  to  44*43  per  cent.  It  is  rapidly 
oxidised  by  f ummg  nitric  acid,  with  formation  of  sulphuric  and  phosphoric 
acids.  (H.  Rose.) 

b.  PS*C1*  or  PCI,  2SC1.     Formed  when  dry  hydrosulphuric  acid  gas  is 
brought  in  contact  with  pentachloride  of  phosphorus, 
PCI*  +  2HS  =  PS*  CP  +  2HC1. 

The  hydrosulphuric  acid  gas  is  either  slowly  passed  over  the  chloride 
of  phosphorus  contained  in  a  glass  bulb ;  or  the  latter  is  poured  into  a 
Teasel  full  of  the  gas.  The  same  compound  is  obtained  if  an  excess  of 
hydrosulphuric  acid  is  employed.  100  parts  of  pentachloride  of  phos- 
phorus yield  81*775  parts  of  the  new  compound.  It  is  purified  by  dis- 
tillation in  a  small  retort. 

Opalescent  at  first;  afterwards  becomes  colourless  and  transparent; 
heavier  than  water.  Boils  at  125"^;  and  fumes  slightly  in  the  air.  Has 
a  characteristic  odour,  somewhat  pungent  and  aromatic,  and  likewise 
smells  of  hydrosulphuric  acid  (formed  by  the  decomposing  action  of  the 
moisture  in  the  air). 

Calculation. 

P      31*4  18-51 

28      32-0  18-87 

3C1     106-2  62-62 

PS«C1« 169-6  100-00 

Water  decomposes  it,  in  the  course  of  a  few  days;  more  rapidly  when 
the  mixture  is  agitated ;  with  the  aid  of  heat,  the  decomposition  is  com- 
plete in  a  few  hours:  the  products  are  hydrochloric,  hydrosulphuric^ 
and  phosphoric  acids. 

PS«C1«  +  6HO  -  P0»  +  2HS  +  3HC1. 
The  water,  however,  is  rendered  milky,  from  separation  of  a  small  quantity 
of  free  sulphur.     Aqueous  ammonia  or  potash  causes  a  similar  decom^ 
position,  but  much  more  rapidly.  (SeruUas.) 

The  oil,  especially  when  warmed,  dissolves  a  small  excess  of  phosphorus 
or  sulphur,  which  a^in  separates  for  the  most  part  on  cooling,  and  remains 
behind  when  the  oil  is  distilled.  (SeruUas,  Ann,  Chim,  JHhps,  42,  25;  also 
Foga.  17,  165 ;  also  Schw.  57,  366;  also  iV^.  Tr.  21, 1,  214.) 

Burning  sulphide  of  carbon  is  extinguished  in  chlorine  gas ;  at  or- 
dinary temperatures,  that  liquid  absorbs  a  small  quantity  only  of  the  gas>, 
which  is  again  expelled  on  heating  the  liquid.  (Berzelius.) 

IT    C.  Chlorosulphidb  of  Carbon.    CSCl. 

Formation  and  Preparation, — 1 .  When  a  few  grammes  of  bisulphide 
of  carbon  are  introduced  into  a  fiask  filled  with  perfectly  dry  chlorine  gas, 
the  flask,  carefully  closed,  and  left  for  a  few  days  either  in  the  dark  or 
in  sun-light,  the  colour  of  the  chlorine  gradually  disappears,  and  the  sul- 
phide of  carbon  is  converted  into  a  liquid  of  a  deep  yellow  colour.  On 
opening  the  fiask,  the  gas  within  is  found  to  be  rarefied.  The  liquid  thus 
formed  is  a  mixture  of  protochloride  of  sulphur  with  the  compound  under 
consideration ; 

cs«  +  2a  »  SCI  +  csa. 


336  CHtORINE. 

Bj  digestion  in  water,  tbe  chloride  of  snlpbiir  is  decomposed  and  the 
chloTosalphide  of  carbon  separates  in  the  form  of  an  oilj  liquid.  To 
parify  it  from  the  acid  producta  formed  by  the  decomposition  of  the  chlo- 
ride of  sulphur,  it  must  be  several  times  distilled  with  water  and  a  small 
quantity  of  mngnesia. — In  preparing  this  compound,  it  is  essential  that 
the  materials  be  perfectly  free  from  moisture;  for  if  water  is  present, 
another  compound  of  chlorine,  sulphur,  and  carbon,  is  produced,  which 
will  be  dei^nbed  immediately.  (See  next  page.)— 2.  By  passing  a  mixture 
of  hydrosulpbnric  acid  gas  and  vapour  of  perchloride  of  carbon,  C*C1^ 
through  a  tube  kept  at  a  moderate  red-heat ;  hydrochloric  acid  is  formed 
at  the  same  time  (Kolbe) : 

ca*  +  Hs  =  Hci  +  csa. 

Properties,  Yellow  liquid,  notmiscible  with  water;  has  a  very  pecu- 
liar and  powerful  odour;  irritates  Ihe  eyes  very  strongly.  Specific  gravity 
=  1*46.  Boiling  point  70°  (158''  P.);  these  numbers  probably  require 
correction,  as  it  is  difficult  to  obtain  the  compound  quite  free  from  bisul- 
phide of  carbon.  (Kolbe). 

Calculation. 

a.  b,  Kolbe. 

C      6     10-45  9-62  10-72 

S       16     27-87  25-66  32-16 

CI    35-4  61-67  56-76  56*76 

CSCl 57-4  100-00  9204  9964 

It  will  be  observed  that  the  experimental  and  calculated  numbers  differ 
considerably.  Kolbe  attributes  this  difference  to  the  presence  of  unde- 
composed  bisulphide  of  carbon ;  indeed,  it  appears  from  calculation  b,  in 
which  the  quantity  of  chlorine  is  made  equal  to  that  determined  by  the 
analysis,  that  the  excess  of  carbon  (1*1),  and  that  of  sulphur  (6*5),  are 
very  nearly  in  the  proportion  in  which  those  elements  exist  in  bisulphide 
of  carbon.  Admitting  the  correctness  of  the  formula  CSCl — ^which  accords 
both  with  the  mode  of  formation  of  the  substance,  and  also  with  its 
reactions — it  will  be  seen  that  the  chlorosulphide  of  carbon  is  the  analogue 
of  phosgene,  COCl,  the  atom  of  oxygen  being  replaced  by  an  atom  of 
sulphur.  It  may  also  be  resfarded  as  CC1\  2CS'.  that  is  to  say,  as  a  com- 
pound of  2  atoms  of  bisulphide  of  carbon  with  1  atom  of  Regnault's 
perchloride  of  carbon,  just  as  phosgene  majr  be  regarded  as  C*C1*,  2C0* 
lyid.  p.  326).  This  view  of  its  constitution  is  also  rendered  probable  by 
its  mode  of  formation.  For,  when  vapour  of  bisulphide  of  carbon  and 
dry  chlorine  gas  are  brought  together  at  a  red  heat,  the  products  are 
perchloride  of  carbon  and  free  sulphur;  so  that,  if  the  second  view  of  the 
composition  of  the  chlorosulphide  be  admitted,  it  will  follow,  that  the 
action  of  chlorine  on  bisulphide  of  carbon  at  ordinary  temperatures,  differs 
from  that  which  takes  place  at  high  temperatures,  only  in  this  respect— 
that,  in  the  former  case,  the  perchloride  of  carbon  produced,  enters  into 
combination  with  a  portion  of  the  undecomposed  sulphide  of  carbon, 
while  in  the  latter,  it  does  not.  (Kolbe.) 

Decompositions.     Chlorosulphide   of  carbon    is   not   decomposed  by 
water  or  by  acids,  not  even  by  fuming  nitric   acid.      Caustic  potash 
decomposes  it  slowly,  the  products  being  carbonate  of  potash,  sulphide  of 
potassmm,  and  perchloride  of  carbon :  thus,  (halving  all  the  numbers), 
2CSCI  +  3K0  =  KO,  C0«  +  2KS  +  CC1« 
or:  CC1«,CS<  +  3KO  =  CC1«  +  KO,CO«  +  2KS. 
This  decomposition  is  in  favour  of  the  second  view  of  the  constitution  of 
the  substance.  (Kolbe,  Ann,  Fharm,  45,  53.)  If 


CARBONATE  OF  BICHLORIDS  OP  SULPHUR.  337 

D.    Carbonate  op  Bichloridb  op  Sulphur.    CSCl'O*. 

Chlor-hyposulphite  of  Chloro-carbonic  oxide,  ChXorunterachwefligsauret 
CMorkohUnoxyd  (Berzelins) ;  OxyMoride  of  Sulphide  of  Carbon, 
SauerUoff-^hlorschwefelkohleMtoff; — Sulphite  of  FerMoiide  of  Carbon, 
Schwejligsaures  Kohlensuperchlorid  (Kolbe). 

Formation  and  Preparation. — 1 .  One  part  of  bisalphide  of  carbon  is 
digested  for  a  long  time  with  16  parts  of  a  mixture  of  fuming  nitric  and 
concentrated  hydrochloric  acid,  the  materials  being  put  into  an  imper- 
fectly closed  vessel,  and  kept  at  a  temperature  of  21°.  CKf  F.)  The 
odour  of  chloride  of  sulphur  becomes  perceptible — the  sulpnide  of  carbon 
acquires  an  orange-yellow  colour — ^then  becomes  paler  and  more  tenacious 
-—nitrous  fumes  are  eyolred — and,  in  the  course  of  three  months,  the 
whole  becomes  converted  into  a  solid  mass,  which  may  be  freed  from 
adhering  acid  by  washing  with  cold  water.  (Berzelius  and  Marcet.) — 2. 
This  substance  is  more  quickly  formed  by  exposing  bisulphide  of  carbon 
to  the  action  of  moist  chlorine  gas.  (Berzelius.)  IT.  A  capacious  glass 
bottle,  holding  about  3  pints  and  fitted  with  a  ground  stopper,  is  half 
filled  with  a  mixture  of  peroxide  of  manganese  and  hydrochloric  acid; 
about  800  grains  of  bisulphide  of  carbon  are  then  added,  and  the  vessel 
quickly  closed.  The  mixture  is  first  placed  for  some  days  in  a  cool 
place,  and  afterwards  exposed,  for  several  days  longer,  to  a  temperature 
of  30^  ('86'^  F.),  and  frequently  shaken,  till  the  greater  part  of  the  bisul- 
phide ot  carbon  is  converted  into  the  new  compound ;  in  summer,  it  is 
best  to  expose  the  mixture  to  the  direct  rays  of  the  sun.  The  action  may 
be  greatly  accelerated  by  adding  from  6  to  10  oz.  of  ordinary  commer- 
cial nitric  acid  to  the  mixture.  There  is  no  danger  of  the  vessel  bursting 
from  internal  pressure,  provided  the  precaution  be  taken  of  raising  the 
stopper  from  time  to  time.  The  whole  contents  of  the  bottle  are  subse- 
quently turned  out  into  a  large  flask,  and  distilled  in  an  oil-bath,  the  vola« 
tile  products  being  condensed  by  means  of  a  Liebig's  condenser,  having  a 
wide  tube  not  turned  down  at  the  lower  end.  The  first  portions  of  the 
distillate  consist  of  undecoraposed  bisulphide  of  carbon,  mixed  with 
another  liquid  of  yellow  colour  and  offensive  odour:  little  or  no  free 
chlorine  escapes.  Afterwards,  the  carbonate  of  bichloride  of  sulphur 
distils  over,  and  solidifies  in  the  condensing  tube ;  when  the  distillation 
is  over,  it  may  be  easily  separated  by  a  gentle  thrust  The  weight  of 
the  product  is  more  than  double  that  of  the  bisulphide  of  carbon  employed. 
The  action  is  as  follows : 

CS«  +  CI*  +  2H0  =  SC1«,C0«  +  2HC1  +  S 
(Kolbe,  Ann.  Pharm,  54,  148.)ir. 

Properties.  Colourless,  transparent,  crystalline  mass,  (apparently 
cubical),  resembling  camphor.  IT.  It  closely  resembles  camphor  in  exter- 
nal appearance,  and,  like  that  substance,  sublimes  when  heated  in  close 
vessels,  condensing  on  the  side  in  small,  colourless,  transparent,  rhombic 
tables,  having  a  diamond  lustre.  The  smaller  angle  of  the  base  is  so  near 
60°,  that,  if  the  opposite  acute  lateral  edges  be  replaced  by  planes,  ai^ 
almost  regular  six-sided  prism  will  be  formed.  Both  forms  are  obtained, 
very  well  developed,  by  slowly  subliming  the  substance  by  the  warmth  of 
the  hand,  in  a  glass  tube  exhausted  of  air  and  hermetically  sealed.  The 
six-sided  prisms  collect  on  the  part  nearest  to  the  hand;  the  rhombic 
prisms  at  the  further  end.     The  crystals  when  moist,  are  white  and 

VOL.   II,  z 


338  CHLORINB, 

opaque,  and  fonn  arborescent  ramificationB  without  definite  crystalline 
form,  like  froet  on  windows.  (Kolbe.)  IT. 

This  substance  fuses  at  a  gentle  heat,  and  crystallizes  again  on  cooling ; 
at  a  somewhat  higher  temperature,  it  sublimes  without  residue.  (Bene- 
lius).  Begins  to  melt  at  185»  {275^  ¥,),  boils  at  170°  (338^  F.),  and 
may  be  distilled,  either  alone  or  with  water.  (Kolbe.)  Odour,  sharp  and 
disagreeable,  resembling  that  of  chloride  of  sulphur;  taste,  sharp,  burning, 
and' afterwards  acid.  (Berzelius.)  Its  odour  is  so  pungent  and  peculiar, 
that  it  may  always  be  detected  by  that  character,  even  in  the  smallest 
quantities ;  it  excites  a  rapid  flow  of  tears,  and  when  inhaled  in  rather 
large  quantities,  produces  an  intolerable  irritation  in  the  throat,  but 
without  otherwise  injuring  the  health.  (Kolbe.)  Does  not  redden  litmus 
paper  when  dry,  barely  when  moist.  (Berzelius.)  Moist  litmus  paper  is 
instantly  reddened  by  it,  in  consequence  of  partial  decomposition.  (Kolbe.) 
Specific  gravity  of  the  yapour  =  7'43.  (Kolbe.) 

CalciUatioii.                        Kolbe.  Benelias  and  Maroet. 

C  60  6-5  5-4  Carbonic  add   21-63 

S  16-0  ........  14-7  14-9  SulphnrouB  acid   29*63 

2C1 70*8  65*1  65*1  Anhydroas  mariatie  \  ao.ja 

20  16'0  14*7  14-6  acid  (hyp.) J  *** '* 


CSC1«0«  ...108*8  1000  100*0  100*00 

(Kolbe.)  Vol.      Sp.  gr. 

Vapour  of  perchloride  of  carbon  CCI*    ....  1  5*29 

Sulphorous  acid  gas,  SO«     1  2*22 


Vapour  of  solphite  of  perchloride  of  carbon....  1  7*51 

(COCI".  +S0  +  2a  =*  619*10  +  301*17  +  442*66  =  1362*93.    BerzcUua.) 

This  compound  may  be  regarded  as  carbonate  of  bichloride  of  sulphur, 
:=SCP,  CO';  or,  with  BerzeUus,  aa  a  compound  of  phosgene  and  hypo^ 
sulphurous  acid,  with  which  one  atom  of  chlorine  is  united,  =  COCl  + 
SOCl;  or,  with  Kolbe,  as  sulphite  of  bichloride  of  carbon,  =  CCP,  SO* 

Deeompontioni. — 1.  By  water,  especially  at  a  boiling  heat,  this  com- 
pound is  gradually  resolyed  into  carbonic,  sulphurous,  and  hydrochlorio 
a«id;  the  same  eneot  is  produced,  but  more  quickly,  by  caustic  potaah* 
CSCl'O"  +  2HO  «  CO«  +  SO«  +  2HC1. 

2.  By  red-hot  iron  filings,  into  chloride  of  iron,  sulphide  of  iron,  car- 
bonic acid,  and  carbonic  oxide. 

IT  3.  When  it  is  heated  with  a  large  excess  of  concentrated  oil  of 
vitriol,  the  products  are  sulphurous  acid,  hydrochloric  acid,  and  phosgene 
gases: 

2(CC1«,S0»)  +  2(H0,S0«)  =  CC1«,C0«  +  2HC1  +  4SO«. 
— L  It  bears  a  moderately  high  temperature  without  alteration ;  but  when 
pajBsed  through  a  glssB  tube  kept  a  dull  red  heat,  it  is  resolyed  into  proto- 
chloride  of  carbon,  sulphurous  acid,  and  free  chlorine,  the  former  distilling 
o^er  in  the  liquid  form,  the  two  latter  escaping  as  gas.  (Kolbe.)  IT.  [For 
other  modes  A  decomposition  see  the  next  page.] 

ComhinoUions, — a.  Soluble  in  bisulphide  of  carbon. — h.  With  ammo- 
nia.— c.  With  alcohol,  ether,  volatile  oils,  and  fixed  oils.  (Berzelius  & 
Marcet^  Schw.  9,  298;  also  Gilb,  48,  161.— Kolbe,  Ann.  Fkarm.  54, 
J4«.) 


CARBONATE  OP  PROTOCHLORIDE  OP  SULPHUR.  839 


IT.    E.    Cabbonatb  of  Protochlobidb  of  Sulphur.    CSGIO* 

Sulphite  of  Protochloride  of  Carbon^  Sckwe/iigsaures  KoMenckhrid, 

Formation,     By  the  action  of  sulphurous  acid  on  the  carbonate  of 
bichloride  of  sulphur,  in  contact  with  water  or  the  elements  of  water, 
sulphuric  and  hydrochloric  acid  being  formed  at  the  same  time. 
CSC1«0»  +  SO*  +  HO  =  CSClO«  +  SO»  +  HCl. 

3.  By  the  action  of  sulphuretted  hydrogen  on  an  alcoholic  solution  of 
CSOIK)^  hydrochloric  being  also  formed  and  sulphur  precipitated : 

csa«o«  +  HS  =  csao*  +  hci  +  s. 

3.  Protochloride  of  tin  dissolves  carbonate  of  bichloride  of  sulphur  in  large 
quantity,  with  great  evolution  of  heat,  the  products  being  bichloride  of  tin 
and  carbonate  of  protochloride  of  sulphur. 

CSC1«0«  +  SnCl  =  CSC10«  +  SnCl«. 

4.  By  the  action  of  nascent  hydrogen  on  the  carbonate  of  bichloride  of 
sulphur,  e.  g,  when  iron  or  zinc  is  digested  in  an  acidulated  solution  of 
that  compound  in  alcohol,  diluted  as  much  as  possible  without  causing  pre- 
cipitation; also  when  the  same  solution  is  decomposed  by  the  electric 
current. 

This  compound  has  not  been  obtained  in  the  separate  state,  and  it  does 
not  combine  with  salifiable  bases :  hence  its  composition  cannot  be  deter- 
mined by  actual  analysis,  but  its  mode  of  formation  and  its  reactions  with 
other  bodies  show  that  it  differs  from  the  preceding  compound,  only  in 
containing  one  atom  less  of  chlorine. 

Calculation. 

C    6     8-17 

S     16     21-80 

CI    85-4  48-23 

20    16     21-80 

cscio*       m       100-00 

It  may  be  regarded  either  as  carbonate  of  protochloride  of  sulphur, 
SCI,  C0^  (in  accordance  with  Gmelin's  view  of  tne  preceding  compound), 
t>r,  with  Kolbe,  as  a  sulphite  of  protochloride  of  carbon,  GC1,S0'. 

This  compound  is  soluble  in  water  and  in  alcohol;  it  is  obtained  in 
the  state  of  solution,  by  passing  a  stream  of  sulphurous  acid  gas  through 
an  alcoholic  solution  of  the  sulphite  of  perchloride  of  carbon.  After  a  oer- 
^in  quantity  of  the  gas  has  been  passed  through,  the  liquid  becomes 
miscible  with  water  without  decomposition :  it  then  contains,  besides  free 
sulphurous  acid,  which  is  easily  expelled  by  heat,  hydrochloric  acid,  sul- 
phuric acid,  and  the  sulphite  of  protochloride  of  carbon.  The  same  results 
are  obtained,  though  more  slowly,  by  digesting  the  sulphite  of  perchlo- 
ride of  carbon  in  aqueous  solution  of  sulphurous  acid. 

The  solution  in  water  or  alcohol  is  colourless  and  inodorous ;  cannot 
be  concentrated  by  evaporation  in  open  vessels;  has  an  acid  reaction 
{arising  from  the  presence  of  sulphuric  or  hydrochloric  acid  9],  but  shows 
no  tendency  to  combine  with  salifiable  bases.  It  has  a  strong;  attraction 
for  oxygen,  and  when  exposed  to  the  air,  is  partially  converted  into  phos- 
^ne  gas  and  sulphuric  acid : 

cscio«  +  20  =  coa  +  so». 

A  small  quantity  of  the  aqueous  solution  spread  out  upon  a  plane  surface 

z  2 


340  CHLORINE. 

80  as  to  expose  as  large  a  surface  as  possible  to  the  air,  will  fill  a  closed 
room  with  the  saffocating  fumes  of  phosgene  and  sulphurous  acid  to  such 
a  degree,  sjb  to  render  the  air  almost  irrespirable. 

Chlorine  gas  passed  through  the  aqueous  solution  produces  a  copious 
white  precipitate,  arising  from  the  reproduction  of  sulphite  of  perchloride 
of  carbon,  which  is  insoluble  in  water : 

CSCIO*  +  CI  =  CSC1«0«. 
Bromine  produces  a  similar  precipitate,  consisting  of  a  compound  contain- 
ing both  chlorine  and  bromine,  which  has  not  b^n  further  investigated. 
Iodine  causes  no  precipitation. 


By  the  action  of  various  reagents  on  the  two  compounds  just  described, 
Kolbe  has  formed  a  series  of  acids  containing  the  elements  of  h  jposulphuric 
acid,  and  of  certain  organic  radicals,  as  formyl,  elayl,  methyl,  &c.  As 
far  as  their  mode  of  formation  is  concerned,  these  compounds  are  strictly 
inorganic;  but  in  their  composition  and  reactions,  they  bear  so  close  a 
resemblance  to  certain  organic  compounds  that  the  consideration  of  them 
is  best  referred  to  the  department  of  Organic  Chemistry  (especially  as  all 
the  hydrocarbons  and  the  chloride  of  defiant  gas  are  referred  by  the 
author  to  that  part  of  the  work :  vid.  p.  326).  A  brief  sketch  of  them 
may  however  be  introduced  in  this  place. 

a.  Chlorocarh-hypomlpkuric  acid,  {ChlorkohlenuTUerschwefd^aure): 
HO,  C*CPS'0*.^-Formed  by  the  action  of  caustic  potash  at  a  gentle  heat 
on  sulphite  of  perchloride  of  carbon. 

2(CC1«,S0«)  +  2KO  =  KO,C«CPS«0*  +  KQ. 
The  hydrate  of  this  acid  crystallizes  in  small  deliquescent  prisms  ;  it  may 
be  partially  sublimed  without  decomposition.  It  is  not  oxidized  by  fuming 
nitric  acid  or  aqna-regia,  and  has  so  powerful  an  affinity  for  bases  that  it 
even  expels  hydrocmorio  acid  from  its  compounds.  Its  salts  are  all 
soluble  in  water  and  alcohol,  and  crystallize  with  facility.  When  heated, 
they  are  resolved  into  phosgene  gas,  sulphurous  acid,  and  metallic  chlo- 
ride. 

K0,C«C1»S«0»  =  CCl«,CO«  +  2S0«  +  KCl. 

h,  Chlorformyl-kypomlphuric  (tcid:  H0,C'HC1'S*0*. — Formed  by  the 
action  of  caustic  alkalis  on  sulphite  ofprotochloride  of  carbon,  the  elements 
of  water  taking  part  in  the  reaction, 

2(CC1,80«)  +  KG  +  HO  =  KO,  C«HC1«S«0»; 
also  by  the  action  of  metallic  zinc  on  the  compound  a,  chloride  of  zinc 
being  formed  at  the  same  time, 

H0,C«C1»S"0»  +  2Zn  «  ZnO,  C*HCI*S«0»  +  Znd. 
Resembles  the  preceding  compound  in  most  of  its  properties.     Its  saJts, 
when  heated,  give  off  phosgene  gas,  sulphurous  acid,  and  water,  and  leave 
a  residue  consisting  of  charcoal  and  metallic  chloride. 

c.  Chhrelaylrhypomlpluric  add:  HO, CH*C1S'0*.— Formed  by  the 
continued  action  of  nascent  hydrogen  on  chlorformyl-hyposulphnric 
acid: 

H0,C«HC1«S«0*  +  2H  =  HO,  C«H«C1S«0»  +  HCl. 

When  zinc  is  immersed  in  an  aqueous  solution  of  chlorformyl-hyposul- 
phuric  acid,  it  dissolves,  with  evolution  of  hydrogen;  and  the  hydrogen, 
as  it  is  set  free,  converts  a  portion  of  the  acid  into  chlorelayl-hyposot- 


CONJUGATE  ACIDS.  341 

phnrio  acid.  But  complete  transformation  can  only  be  attained  hj  Bub- 
jecting  an  acidulated  solution  of  a  salt  of  acid  a  or  6  to  the  action  of  the 
galvanic  current. — The  hydrate  of  this  acid  is  a  viscid^  strongly  acid 
liquid^  Trbich  bears  a  heat  of  140**  C.  without  decomposition;  at  —  16'6®C. 
it  assumes  a  syrupy  consistence  ;  in  other  respects^  it  resembles  the  com- 
pound a.  All  its  salts  are  soluble  in  water,  and  most  of  them  crystalli- 
zable. 

d.  MethyUhypowlphuric  acid :  HO,  CH^'O'.— This  acid,  which  differs 
from  the  rest  of  the  series  in  not  containing  chlorine,  is  formed  when  a 
neutral  solution  of  chlorocarb-hyposulphate  of  potash  is  decomposed  by 
the  electric  current,  the  electrodes  being  formed  of  amalgamated  zinc 
plates : 

KO,C«a*S«0*  +  6Zn  +  6H0=  KO,  C«H*S«0*  +  6ZnO  +  3HC1. 

Also  when  amalgam  of  potassium  is  immersed  in  the  same  solution : 

KO,  C«C1»S«0*  +  6K  +  3H0  =  KO,  C«H»S«0*  +  3KC1  +  3K0. 
In  both  oases,  the  immediate  agent  in  the  conrersion  is  nascent  hydrogen : 
no  hydrogen  is  evolyed  till  the  transformation  is  complete. — The  concen- 
trated solution  of  this  acid  is  a  sour,  inodorous,  viscid  liquid,  which  may 
be  heated  to  nearly  130^  C.  without  decomposition :  at  that  temperature, 
it  begins  to  turn  brown  from  commencing  decomposition.  Does  not  crys- 
taUize  when  pure.  In  stability  and  affinity  for  salifiable  bases,  it  is  not 
inferior  to  chlorocarb-h3rposufphuric  acid.  Its  salts  are  soluble  and 
crystallizable.  (Kolbe.  BeUrage  zur  Kenntniss  der  gepaarten  Verbindun" 
gen,  Ann.  Fharm.  49,  339;  54,  143.)  IT 


F.  SiTLPHATB  OF  HYDROCHLORIC  AciD. — Anhydrous  sulphuric  acid 
absorbs  a  very  large  quantity  of  hydrochloric  acid,  being  thereby  converted 
into  a  transparent  and  colourless  liquid. — Oil  of  vitriol  does  not  absorb 
hydrochloric  acid  gas.  (Aim6,  J,  Fharm,  21,  88;  also  J,  pr,  Chem, 
6,  79.) 

G.  Sulphate  of  Pentachloride  of  PHosPHORUtt*— Vapour  of  anhy- 
drous sulphuric  acid  is  passed  in  excess  over  terchloride  of  phosphorus 
contained  in  a  receiver  surrounded  with  ice,  the  liquid  decanted  from  the 
excess  of  acid  which  has  solidified  in  the  receiver,  and  then  distilled.  Sul- 
phurous acid  is  evolved  (inasmuch  as  part  of  the  phosphorus  is  converted 
into  phosphoric  acid,  and  the  terchloride  of  phosphorus  thereby  converted 
into  pentachloride).  Between  40^  and  50%  which  range  of  temperature 
is  maintained  for  a  da^,  another  portion  of  superabundant  acid  passes  over 
and  condenses  in  the  ice-cold  receiver;  afterwards,  at  a  somewhat  higher 
temperature,  a  mixture  of  sulphuric  acid  and  the  new  compound  distils 
over,  and  solidifies  after  some  time :  finally — the  receiver  having  been 
changed — there  passes  over  a  liquid  which  does  not  solidify  at  any  tem- 
perature. Nevertheless,  its  boiling  point  is  not  constant,  and  it  underfi;oes 
more  or  less  alteration  every  time  it  is  distilled.  It  begins  to  boU  at 
137**;  then  the  boiling  point  rises  to  160° — 165°;  and  in  the  retort  there 
remains  a  syrup  which  dissolves  in  water  with  great  evolution  of  heat, 
producing  sulphuric,  hydrochloric,  and  phosphoric  acid;  when  more 
strouffly  heated,  it  leaves  a  gummy  residue  of  metaphosphoric  acid. 

The  compound  when  purified  by  distiUation,  is  of  an  oily  consistence. 
When  poured  into  water,  it  sinks  to  the  bottom  in  drops,  which  slowlv 
dissolve;  yielding  hydrochloric,  sulphuriCi  and  ordinary  phosphoric  acid. 


I 


342  CHLORINE. 

The  oil  may  be  regarded  as  a  compound  of  sulphntic  acid  and  pentacblo- 
ride  of  phosphoros,  often  mixed  with  pentasulphate  of  terchloride  of  sul- 
phur ;  or  as  a  loose  and  variously  constituted  compound  of  pentasulphate 
of  chloride  of  sulphur  with  phosphate  of  pentachloride  of  phosphorus.  (H. 
Rose  prea  the  preference  to  the  latter  riew.)  Different  portions  of  the 
liquid  prepared  at  different  times,  or  collected  at  different  stages  of  the 
distillation,  were  found  to  contain,  in  100  parts,  the  following  quantities 
of  sulphur  and  chlorine : 

abode 

S  21-90  11'47  7-51  11-84  13-59 

a 38-41  49-51  58-91  5209  5136 

d  and  e  were  obtained  by  a  second  rectification ;  moreoyer,  d  was  the 
second,  and  e  was  the  tnird  part  of  the  distillate.  (H.  Rose^  Pogg-  44, 
304.) 

H.    Sulphate  of  Tbrohloridb  of  SirLPHm. 

a.      BiBULPHATB  OF  TeRCHLORIDB  OF  SULPHITB.      SCP,  2S0^ 

Chlarosidphuric  acid,  CMwschwefeUdure^  Acide  ehlorotu^rique. 

A  mixture  of  sulphurous  acid  and  chlorine  gases  in  equal  volumes, 
exposed  to  sunshine  in  the  month  of  June,  produces  fumes  in  the  course 
of  a  few  hours ;  and  after  some  days,  condenses,  for  the  most  part,  to  a 
liquid.  This  liquid  may  be  purified  by  distillation  over  mercury,  the 
receiver  being  cnanged  after  a  while,  because  the  first  portions  of  the 
distillate  contain  sulphurous  acid.  (Regnault.) 

Colourless  liquid,  of  specific  gravity  1659,  at  20*  (eS**  P.);  boils  at 
77,  (170-6'*  F.)  ;  specific  gravity  of  the  vapour,  4-665.  (Regnault.) 

Calculation,  according  to  Regnault  Or. 

8 1 16-0 23-74  SO« 320 47*48 

O 2 160 23-74  CI   35*4 52-52 

CI 1 35-4 52-52 

SC10«....1 67-4....  10000  80«,CL...67-4 1000 

Vol.  Sp.  gr. 

SulphurooB  add  gas  ....  1  2*2186 

Chlorine  gaa 1  2-4543 

Vqjour  1  4-6729 

May  be  regarded  ajB  sulphurous  acid,  in  which  1  At.  0  is  replaced  by 
1  At.  01,  or  as  a  comnound  of  sulphurous  acid  with  chlorine,  or  as  a 
compound  of  terchloride  of  sulphur  with  sulphuric  acid :  3  (SCIO*)  = 
8C1»  +  2S0». 

Water  converts  it,  with  great  evolution  of  heat,  into  hydrochloric) 
and  sulphuric  acid. 

80*C1+  HO==SO«+  HCl. 

It  does  not  combine  with  salifiable  bases,  and  therefore,  perhaps,  scarcely 
deserves  to  be  called  an  acid.   (Regnault.) 

The  following  process  yields  this  compound,  mixed  with  about  an 
equal  quantity  of  oil  of  olefiant  gas.  A  mixture  of  sulphurous  acid  and 
defiant  gases  evolved  by  heating  1  part  of  absolute  alcohol  with  6  parts 
of  oil  of  vitriol,  is  passed  through  two  bottles  filled  with  oil  of  vitriol/by 
which  ether  vapour  and  aqueous  vapour  are  absorbed,  and  then  mixed 
in  «  glass  globe  with  dry  chlotine  gas.      The   two  gaaes  condense 


SULPHATE  OF  T£RCHLORID£  OF  SULPHUE.        343 

into  a  liquid^  of  pungeni^  suffooating  odour.  It  may  be  freed  from 
adhering  snlphurous  acid  and  chlorine  by  distillation ;  but  the  receiver 
must  be  changed  after  a  while,  because  the  sulphurous  acid  and  chlorine 
pass  over  first.  From  oil  of  defiant  gas,  however,  it  cannot  be  entirely 
freed ;  because  the  boiling  points  of  that  liquid  and  of  chlorosulphurio 
acid  are  nearly  equal. 

The  compound  obtained  by  this  process  contains  from  29  to  51  per 
cent,  of  oil  of  defiant  gas,  and  71 — 49  of  chlorosulphuric  acid. 

In  water,  chlorosulphuric  acid  is  converted — ^with  separation  of  the 
oil  and  great  development  of  heat — into  sulphuric  and  hydrochloric  acid; 
the  same  effect  is  produced,  but  more  rapidly,  by  potash.  On  the  other 
hand,  the  liquid  may  be  distilled  over  burnt  lime  or  baryta  without  de- 
composition. In  contact  with  ammoniacal  gas,  the  chlorosulphuric  acid 
contained  in  it  is  converted  into  sal-ammoniac  and  sulphamide  (SO'CI 
-♦-2NH"  =  NH»,  HCl  +  NH'SO'.)  {Re^mnXt). 

b.    Pentabulphatb  of  Tbbchloiude  of  Sulphub,  SC1*,5S0^ 

Piyparatian.  Dichloride  of  sulphur  surrounded  with  a  freezing  mix- 
ture rapidly  absorbs  the  vapour  of  anhydrous  sulphuric  acid,  thereby 
acquiring  a  brown  colour;  but  if  afterwards  kept  for  24  hours  in  a  close 
vessel,  at  0^,  it  regains  its  yellow  colour,  provided  the  sulphuric  acid  is 
not  in  excess.  At  temperatures  below  0^,  no  sulphurous  acid  escapes;  but 
a  few  degrees  above  0^,  that  gas  is  rapidly  evolved,  sometimes  bursting 
the  containing  vessel.  When  heated  in  a  retort,  the  liquid  soon  boils, 
with  violent  evolution  of  sulphurous  acid;  and,  if  the  sulphuric  acid  is 
not  in  excess,  the  evolution  of  sulphurous  acid  continues  tor  a  while,  as 
the  temperature  gradually  rises ;  tnen,  between  30°  and  40°,  chloride  of 
sulphur  passes  over ;  then  a  mixture  of  the  latter  with  pentasulphate  of 
terchloride'of  sulphur;  and  lastly,  at  145°,  the  pentiuBulpnate  in  a  state  of 
purity.  The  firee  chloride  of  sulphur  mixed  with  the  pentasulphate  may 
be  removed  by  rectification. 

3S«a  +  15SO>  =  sa»,  5S0*  +  15S0«, 
When  anhydrous  sulphuric  acid  is  paased  in  large  excess  through 
dichloride  of  sulphur,  a  thin  blue  liquid  is  obtained-— or  a  solid  if  the 
acid  is  in  yery  great  excess — which,  when  heated,  becomes  colourless^ 
evolves  sulphurous  acid,  and  is  converted  into  a  mixture  of  pentasulphate 
of  terchloride  of  sulphur  and  excess  of  sulphuric  acid.  On  heating  this 
liquid  still  further,  sulphuric  acid  passes  over  first,  then  a  mixture  of  that 
acid  with  pentasulphate  of  terchloride  of  sulphur,  and  finally  the  latter 
alone.  The  blue  colour  is  due  to  the  combination  of  the  anhydrous  sul- 
phuric acid  with  a  portion  of  the  sulphur  contained  in  the  dichloride. 
— 2.  From  20  to  30  volumes  of  good  fuming  oil  of  vitriol  are  mixed  with 
one  volume  of  chloride  of  sulphur  saturated  as  much  as  possible  with 
chlorine ;  and  the  dark  brown  mixture,  on  the  durfaee  of  which  a  lighter 
coloured  liquid  generally  floats,  is  subjected  to  distillation.  The  excess 
of  chloride  of  sulphur  passes  over  first,  together  with  a  large  quantity  of 
sulphurous  acid ;  afterwards  the  sulphuric  acid  compound,  which  should 
be  collected  in  a  separate  receiver;  common  oil  of  vitriol  remains  in  the 
vetort.  The  liquid  is  distilled  till  the  residue  no  longer  precipitates  a 
silver  solution,  and  the  distillate  freed  by  rectification  from  oil  of  vitriol 
which  may  have  passed  over  with  it  in  the  previous  distillations.  (H. 
Rose.) 


344  CHLORINE. 

Colourless,  oily  liquid,  specific  gravity  =  I  •818,  at  16<*  (60-8°  F.), 
boils  at  145^  (293^  F.);  distils  without  residue.  Specific  gravity  of  the 
vapour,  4*481.  Fumes  strongly  in  the  air,  but  less  strongly  than  anhy- 
drous sulphuric  acid;  has  a  peculiar  odour,  quite  distinct  from  that  of 
sulphurous  acid.  (H.  Rose.)  ^ 

Calculation.  H.  Rose. 

6S      960  29-80  30-35 

150      120-0  37-24  3815 

3C1     106-2  32-96  31-50 


S«0»*C1»  322-2  100-00  100-00 

Vol.           Sp.  gr.  Vol.  Sp.  gr. 

Salphnric  add yapour      2  133112    =    i  1-3311 

Oxygen  gas   15  166395    =  IJ  1-6639 

Chlorine  gaa  6  14-7258    =    |  1.4726 

Vapour 10  44-6765    =    1  4-4676 

May  be  regarded  as  2  At.  sulphuric  acid  in  which  1  At.  0  is  replaced 
by  1  At.  01,  =  S»0*C1. 

Decompositions.  The  vapour  of  this  compound  withstands  a  tempera- 
ture of  217®  (423°  F.)  without  decomposition;  but  when  passed  through 
a  red-hot  tube,  it  is  partly  resolved  into  sulphurous  and  sulphuric  acid, 
the  quantity  decomposed  increasing  as  the  tube  is  more  strongly  ignited^ 
so  that,  as  the  process  goes  on,  the  portion  which  remains  undecomposed 
becomes  mixed  with  a  continually  increasing  quantity  of  free  sulphuric 
acid.  [The  decomposition  probably  takes  place  in  this  manner :  S'CCl* 
=  3S0*  +  3S0*  4-  3C1].  When  the  tube  is  at  a  dull  red  heat,  the  dis- 
tiUate  contains  about  SOP  +  7S0';  at  a  stronger  heat,  SOP  +  IISO';  at 
a  still  higher  temperature,  the  quantity  of  sulphuric  acid  becomes  so 
great,  that  a  portion  of  it  crystallizes  out. — 2.  Under  water,  the  com* 
pound  is  slowly  resolved  into  sulphuric  and  hydrochloric  acid. 
S«0*C1  +  HO  =  2SO»  +  HCl. 

When  put  into  water,  it  first  sinks  to  the  bottom  in  oily  drops,  and 
does  not  dissolve  for  several  hours,  even  when  stirred.  It  appears  to  be 
converted  into  a  hydrate  before  it  dissolves.  If  it  contains  free  chloride 
of  sulphur,  it  deposits  sulphur  when  decomposed  by  water,  and  emits  a 
faint  odour  of  sulphurous  acid. — 3.  When  this  compound  is  mixed  with 
common  salt,  great  heat  is  evolved,  and  a  solid,  translucent  mass  is 
formed,  which  no  longer  fumes  on  exposure  to  the  air.  When  this  mass 
is  subjected  to  distillation,  part  of  the  pentasulphate  passes  over  unde- 
composed, but  mixed  with  free  chlorine;  the  remaining  portion,  together 
with  the  salt,  is  converted  into  chlorine,  sulphurous  acid,  and  bisulphate 
of  soda.  (H.  Rose.)     Probably  in  this  manner : 

NaCl  +  8«0»»Cl*=  NaO,2SO»  +  4SO»  +  4CI. 

Combinations,  a,  Miscible  with  excess  of  anhydrous  sulphuric  acid, 
which,  however,  passes  over  first  when  the  mixture  is  distilled — ^and  is 
therefore  but  loosely  combined. 

6.  Absorbs  chlorine  gas  and  forms  a  yellowish  green  liquid,  which 
smells  strongly  of  chlorine — evolves  that  gas  with  efierrescence,  even  at 
25° — appears  to  boil  at  112° — and  becomes  colourless  again  after  the 
chlorine  nas  escaped. 

c.  With  ammonia :  vid.  Nitrogen  and  Chlorine, 


CHLORIDE  OF  SELENIUM.  345 

IT  L  Sulphate  of  Bichloride  op  Sulphur.  SCT,  SO*. 

Discovered  by  Mil  Ion:  formed  by  the  action  of  moist  chlorine  gas 
on  snlphnr^  or  chloride  of  sulphur. — Lar^e^  transparent^  colourless  crystals, 
which  are  decomposed  by  alcohol  or  water,  or  even  by  exposure  to  damp 
air.  "When  heated  in  a  tube,  they  fuse,  and  are  converted  into  a  very 
mobile  liquid,  which  is  isomeric  with  them.  This  liquid,  when  digested 
in  water,  undergoes  slow  decomposition,  the  products  being  sulphuric, 
sulphurous,  and  hydrochloric  acids : 

8C1«,  SO«  +  2HO  =  S0»  +  SO*  +  2HC1. 

(Millon.  J.  Pharm,  6,  413;  abstr.  Ann.  Fkarm.  52,  230.)  IT. 

Chlorine  and  Selenium. 
A.    Chloride  op  Selenium. 

Selenium,  when  chlorine  gas  is  passed  over  it,  melts  at  first,  with 
disengagement  of  heat,  to  a  brown  liquid,  which  is  afterwards  converted 
by  a  larger  quantity  of  chlorine  into  a  white  solid  mass ;  on  adding  sele« 
mum  to  this  substance  as  long  as  it  is  dissolved,  the  white  mass  is  again 
converted  into  a  brown  liquid. 

a.    Dicfdoride  of  Selenium. 

Transparent,  brownish  yellow  oil,  heavier  than  wafer;  volatile. 
— Slowly  decomposed  by  water  into  hydrochloric  acid,  selenious  acid,  and 
selenium,  which  long  retains  a  small  quantity  of  chlorine,  and  with  it  an 
oily  consistence.   (Berzelius.) 

2Se*Cl  +  2HO  —  SeO*  +  3Se  +  2HC1. 

Calcalation,  according  to  Benelius. 

286    80-0  69-3 

CI  35-4  30-7 

Se«a    115-4  100-0 

5.     Bichloride  of  Selenium, 

White  solid  mass,  which  volatilizes  in  yellow  vapours  more  readily  than 
a;  does  not  fuse  before  volatilizing,  but  merely  contracts,  and  deposits 
itself  on  colder  substances  in  small  white  crystals.  These,  when  again 
sublimed,  unite  into  a  dense  mass  which  cracks  on  cooling.  With  water 
it  forms,  with  rise  of  temperature  and  slight  effervescence,  a  colourless 
and  transparent  solution  of  hydrochloric  and  selenious  acids. 

Sea«  +  2HO  =  SeO«  +  2HC1. 
(Berzelius,  Ann,  Chim.  Fht/s.  9,  225.) — When  a  seleniate  is  heated  with 
common  salt  and  oil  of  vitriol,  no  terchloride  of  selenium  is  obtained ; 
but  bichloride  of  selenium  mixed  with  free  chlorine  passes  over  first,  and 
then  an  oily  mixture  of  selenious  acid  and  sulphuric  acid  in  green  vapours. 
(H.  Rose,  Fogg.  27,  575.) 

CalcnlattoDi  according  to  Berzeliu. 

Se    40-0  36-1 

2C1    70-8  63-9 

I     SeCl« 110-8  100-0 


&46  CHLORINE. 


B.    Sulphate  of  Chlobidb  of  Selenium? 

Bichloride  of  seleninm  absorbs  the  yapour  of  anbjdrons  salphnrie 
acid  but  slightly  at  ordinary  temperatures;  but  if  the  yessel  containing 
the  two  substances  is  closely  corked  and  placed  in  a  warm  room,  the  two 
bodies  slowly  unite,  without  disengagement  either  of  sulphurous  acid  or 
of  chlorine,  and  form  a  yery  dense,  greenish  yellow  syrup ;  the  excess  of 
sulphuric  acid  remains  in  a  crystalline  form.  On  distilling  the  syrup  at 
a  gentle  heat,  the  excess  of  sulphuric  acid  passes  oyer  first ;  the  residue 
in  the  retort  solidifies,  on  cooling,  to  a  white  crystalline  mass.  This, 
when  more  strongly  heated,  melts  to  a  light  brown  liquid  and  eyolyes — 
with  disengagement  of  chlorine,  but  not  of  sulphurous  acid — a  reddish 
yellow  yapour  resembling  hyponitric  acid,  which  condenses  to  a  colour- 
less syrup,  and  finally  to  a  white  mass  resembling  wax.  The  latter  sub- 
stance is  ^ed  from  adhering  chlorine  by  a  second  distillation.  After 
this  treatment,  it  boils  constantly  at  187^  and  may  be  redistilled 
without  leaving  any  residue  or  undergoing  further  decomposition. — It 
contains  on  the  ayerage  12' 895  per  cent,  of  sulphur  and  36*885  of  chlo- 
rine ;  and,  according  to  H.  Rose,  may  be  regarded  as :  2  (SeCP,  5S0') 
+  5  (SeCl^  SeO').  It  deliquesces  rapidly  in  the  air,  exhaling  the  odour 
of  hydrochloric  acid,  and  dissolves  readily  in  water,  without  first  sink- 
ing to  the  bottom  in  oily  drops ;  the  solution,  which  is  generally  coloured 
red,  from  the  presence  of  a  small  quantity  of  free  selenium,  contains 
hydrochloric,  sulphuric,  and  selenious  acid  (no  selenio  acid).  (H.  Rose, 
Fogg.  44,  315.  [If  the  compound  is  regarded  as:  2  (Se*CP)  -h  560', 
the  percentage  will  be  :  28*96  6e,  84*83  CI,  14*48  S,  and  21*72  O.] 


Ghlorimb  and  Iodimb. 

A.      CHLOBtDE  OF   lODIKE. 

Dry  iodine  rapidly  absorbs  chlorine  gas,  the  temperature  rising  to 
100^;  when  the  iodine  is  in  excess,  the  resulting  compound  is  reddush- 
brown  and  fluid;  but  when  the  chlorine  predominates,  it  is  yellow  and 
solid.  (Gay-Lussao.) 

a.    Protochloridb  of  Iodine. 

Preparation. — 1.  By  passing  dry  chlorine  gas  over  dry  iodine  till  the 
latter  is  converted  into  a  perfectly  fluid  compound,  but  no  longer.— 2.  By 
distilling  I  part  of  iodine  with  4  parts  of  chlorate  of  potash.  In  this 
case,  oxygen  gas  is  disengaged  and  a  mixture  of  iodate  and  perchlorate 
of  potash  remains  in  the  retort.  (Berzelius,  Lekrb.  1,  261.)  Since  this 
distillate,  according  to  Berzelius,  is  yellow  or  reddish  coloured,  and  is 
also  capable  of  taking  up  an  additional  quantity  of  iodine,  a  question 
arises  whether  it  may  not  contain  somewhat  more  than  one  atom  of 
chlorine. 

Properties.  Reddish-brown,  oily  liquid  (Gay-Lussac),  having  a  pene- 
trating odour  of  chlorine  and  iodine  (Gay-Lussac);  attacks  the  eyes 
strongly  (Kane);  tastes  slightly  acid,  powerfully  astringent,  and  biting. 
(Berzelius.)    Stains  the  skin  deep  yellow  and  produces  smarting.  (Kane.) 


PROTOCHLORIDB  OF  IODINE.  &47 

Decolorizes  solution  of  indigo  (Gay-Lussac) .  uid  litmus ;  does  not  give  a 

blue  colour  with  starch.   (D.  v  ogel.) 

Calcnlatioii.  Kane.  Vol. 

I    1260  78-07  76-94  Vapour  of  lodinfi  1 

CI  35-4  21-93  23-06  Chlorine  gaa     1 

ICl 16  W      ...100-00      ....100-00 

Decompositions. — 1.  This  compound,  when  heated,  gives  off  terchlo- 
ride  of  iodine,  whilst  pure  iodine  remains  behind.  A  concentrated 
aqueous  solution  inaj  likewise  be  resolved  by  repeated  distillation 
into  terchloride  of  iodine,  which  passes  over,  and  a  residue  of  iodine. 
(Kane.) — 2.  An  aqueous  solution  of  sulphurous  or  of  hydrosulphuric  acid 
blackens  protochloride  of  iodine  by  separating  iodine  from  it.  (A.  Vogel, 
Kastn,  Arch.  10,  119.) — 3.  A  concentrated  solution,  treated  with  red  or 
brown  peroxide  of  lead,  oxide  of  copper,  or  red  oxide  of  mercury,  yields 
a  metallic  chloride  and  iodide,  with  separation  of  a  small  quantity  of 
iodine  and  considerable  evolution  of  oxygen  gas.  (Kane.)— 4.  With 
aqueous  solutions  of  the  fixed  alkalis,  protochloride  of  iodine  yields 
metallic  chloride,  alkaline  iodate,  and  free  iodine ;  and  the  iodine  dis- 
solves in  excess  of  the  alkali,  yielding  iodide  and  iodate.  (Gay- 
Lussac.) 

6KO  +  5IC1  =  5Ka  +  KO,  10*  +  41. 

— 5.  With  aqueous  ammonia,  it  yields  hydrochlorate  of  ammonia  and  a 
precipitate  of  iodide  of  nitrogen.  (Mitscherlich.) 

3IC1  +  4NH>  =  3(NH»,HC1)  +  NI». 
—•6.  From  a  concentrated  solution  of  protochloride  of  iodine,  a  strong  solu- 
tion of  corrosive  sublimate  throws  down  iodide  of  mercury,  leaving  ter- 
chloride of  iodine  in  solution.  (Kane.) 

2ICI  +  HgCl  =  Hgl  +  ia». 

From  a  concentrated  aqueous  solution  of  this  compound,  a  small  quantity 
of  an  aqueous  solution  of  protochloride  of  tin  separates  iodine;  on  the 
addition  of  a  larger  quantity  of  the  chloride  of  tin,  however,  the  iodine 
disappears,  and  brilliant  orange-coloured  needles  of  prot-iodide  of  tin  make 
their  appearance.    First : 

la  +  Sna  «  I  +  SnCl«; 
Afterwards,  with  ^2  atoms  more  of  chloride  of  tin : 

la  +  3SnCl  =  SnI  -|-  2Sna^  (Kane). 

Combinations,  a.  Protochloride  of  iodine  deliquesces  in  the  air  and  is 
very  soluble  in  water.  (Gay-Lussac.)  A  solution  of  the  protochloride  is 
obtained  when  a  small  quantity  of  chlorine  is  passed  through  water  in 
which  an  excess  of  finely  divided  iodine  is  diffused.  The  concentrated 
solution  is  dark  brownish  red;  a  dilute  solution,  dark  reddish  yellow;  the 
former  resembles  the  dry  protochloride  in  its  odour  and  in  the  other  effects 
which  it  prodaces  on  the  body.  When  exposed  to  a  very  low  tempera- 
ture, it  deposits  a  large  quantity  of  a  reddish  yellow  substance  which  again 
dissolves  on  the  application  of  heat.  (Kane.) 

h.  Dissolves  in  alcohol,  forming  a  yellow  solution. 

c.  Ether  separates  protochloride  of  iodine  from  an  aqueous  solution, 
and  deposits  it  unchanged  on  evaporation.  (Dumas.) 


348  CHLORINE, 


b.    Terchlorids  of  Iodine. 

FomuUion* — 1.  B^  treating  iodine  with  excess  of  chlorine  gu.-— 
2.  Finely  diyided  iodine  introdaced  into  dry  hydrochloric  acid  gas,  forms 
liquid  chloride  of  iodine,  with  erolution  of  heat  and  ehullition:  on  coolings 
the  chloride  of  iodine  ciystallizes  in  long  needles.  (Serollas.)  The  reac- 
tion is  donhtless  attended  with  disengagement  of  chlorine  : 

I0»  +  5Ha  =  lOT  +  5HO  -h  2a. 
A  mixture  of  strong  hydrochloric  acid  and  crystallized  iodic  acid,  evolves 
chlorine  and  yields  terchloride  of  iodine.  (Sonheiran.)  When  dilate 
hydrochloric  acid  is  mixed  with  iodic  acid,  it  instantly  tarns  yellow,  and 
on  the  addition  of  oil  of  vitriol  deposits  terchloride  of  iodine.  (Serallas.) 
.  Chlorine  gas  is  likewise  disengaged.  (Soabeiran.) 

Preparation.  Dry  chlorine  gas  is  passed  over  dry  iodine  for  six 
hoars,  and  in  large  excess,  the  mass  being  gently  heated  and  frequently 
stirred.  (Soubeiran.)  SeruUas  recommends  that  the  mass  obtained  he 
treated  with  a  very  small  quantity  of  an  aqueous  solution  of  terchloride 
of  iodine,  to  remove  any  protochforide  of  iodine  which  may  be  present; 
though  he  himself  adds  that  the  residue,  after  this  treatment,  may  contain 
a  large  quantity  of  iodic  acid. 

Properties,  Orange-yellow.  Crystallizes  on  cooling  after  fusion  in  long 
needles.  (Serullas.)  Acts  on  other  substances  in  the  same  manner  as  the 
protochloride.  (Kane.)  Decolorizes  solution  of  indigo.  (Gay-Lussac.) 
Does  not  turn  starch  blue,  except  on  the  addition  of  an  aqueous  solution 
of  protochloride  of  tin. 

Calculation.  Kane.  Vol. 

I  126>0  64*26  54*34  Vapour  of  Iodine 1 

3C1    ....  106*2  45*74  45*66  Chlorine  gas 3 

IC1»  ....  232*2  100*00 100*00 

DecompontioTis. — 1.  Terchloride  of  iodine  melts  at  a  temperatare 
between  20°  and  25°,  evolving  chlorine  gas,  which  it  again  absorbs  on 
cooline.  (Serullas.) — 2.  In  contact  with  a  very  small  ouantity  of  water,  it 
is  resolved  into  an  insoluble  yellowish  portion  [probably  a  mixture  of  ter- 
chloride of  iodine  and  iodic  acidi,  and  a  solution  of  protochloride  and 
terchloride  of  iodine  [and  hydro<mloric  acid  1].  (Serullas.)  One  portion 
of  the  terchloride  probably  dissolves  undecomposed;  the  rest  is  resolved 
into  hydrochloric  acid,  iodic  acid,  and  protochloride  of  iodine : 
2IC1>  -f  5HO  =  5HC1  -f  10*  +  ICl. 

On  treating  anhydrous  terchloride  of  iodine  with  an  aqueous  solution  of 
terchloride  of  iodine,  a  small  Quantity  of  iodic  acid  separates,  the  quantity 
of  which  is  greatly  increased  by  the  addition  of  alcohol ;  the  same  oocuni 
when  terchloride  of  iodine  is  moistened  with  water  and  then  treated  with 
absolute  alcohol  or  ether,  (jp.  225.)  (Serullas.) 

Terchloride  of  iodine  is  less  readily  dissolved  by  water  than  the  pro* 
tochloride ;  the  saturated  solution  may  be  regarded  either  as  aqueous  ter- 
chloride of  iodine — which  is  the  more  probable  supposition— or  as  a  mix- 
ture of  hydrochloric  acid  and  iodic  acid  containing  free  iodine ;  or  as  a 
mixture  of  hydrochloric  acid  and  an  acid  of  iodine  which  contains  3  atoms 
of  oxygen. 


TEKCHLORIDB  OP  IODINE.  349 

51C1»  +  16HO  =  15Ha  +  3105  +  21; 
or :  ICP  +  3HO  =  3HC1  +  10*. 
A  similar  solution  is  obtained  on  passing  chlorine  gas  to  saturation,  through 
1  part  of  iodine  diffused  in  4  parts  of  water,  the  mixture  being  kept  cool, 
and  the  excess  of  chlorine  afterwards  removed  by  a  current  of  atmospheric 
air.  The  solution,  when  saturated  with  chlorine  as  completely  as  possible, 
has  a  bright  yellow  colour,  and  contains  rather  more  than  3  atoms  of  chlo- 
rine, to  1  atom  of  iodine,  because  the  water  giyes  rise  to  the  formation  of 
a  small  quantity  of  hydrochloric  acid  and  iodic  acid.  (Soubeiran.)  Solu- 
tion of  terchloride  of  iodine  may  also  be  prepared  by  precipitating  an 
aaneous  solution  of  the  protochloride  with  corrosive  sublimate,  and  dis- 
tilling the  liquid  after  decanting  it  from  the  precipitated  iodide  of  mercury. 
When  an  aqueous  solution  of  terchloride  of  iodine  is  gradually  mixed 
with  oil  of  vitriol,  and  the  vessel  kept  cool,  the  terchloride  separates  in 
the  form  of  a  white  curdy  mass,  which  afterwards  assumes  an  orange- 
yellow  colour ;  on  heating  the  mixture,  it  dissolves,  but  separates  again  as 
the  liquid  cools ;  on  distilling  the  mixture,  the  terchloride  passes  over. 
(Serullas.)  Ether  does  not  separate  terchloride  of  iodine  from  an  aqueous 
solution  (Dumas) ;  but  if  protochloride  of  iodine  is  also  present,  the  ether 
takes  up  terchloride  of  iodine  in  company  with  it,  provided  the  solution  is 
not  too  dilute.  (Serullas.)  An  aqueous  solution  of  terchloride  of  iodine 
neutralized  with  a  fixed  alkali,  yields  metallic  chloride,  alkaline  iodate, 
and  a  precipitate  of  iodine,  which  redissolves  in  an  excess  of  alkali  in  the 
form  of  iodide  and  iodate.  (Liebig.) 

5IC1"  +  18K0  =  15KC1  +  3(KO,  I0»)  +  2l. 

On  mixing  the  aqueous  solution  with  an  aqueous  solution  of  normal  iodate 
of  potash,  and  then  adding  alcohol,  biniodate  of  potash  is  precipitated. 
(Serullas.)  An  aqueous  solution  of  terchloride  of  iodide  agitated  with  a 
small  quantity  of  oxide  of  silver,  yields  chloride  of  silver  and  iodic  acid; 
when  a  larger  quantity  of  oxide  of  silver  is  used,  the  chloride  of  silver  is 
mixed  with  iodate  of  silver.  (Serullas.)  Iodide  of  silver  is  probably 
formed  at  the  same  time, 

3ICP  +  lOAgO  =  9AgCl  +  Agl  +  2I0». 
Silver  leaf  is  converted  by  aqueous  terchloride  of  iodine  into  chloride  and 
iodide  of  silver.  (Serullas.)  When  aqueous  terchloride  of  iodine  is  mixed 
with  a  small  quantity  of  a  solution  of  protochloride  of  tin,  a  precipitate  of 
iodine  is  obtained,  which  dissolves  on  adding  a  larger  quantity  of  chloride 
of  tin,  without  separation  of  needles  of  protiodide  of  tin.  (Kane.) 
Terchloride  of  iodine  unites  with  metallic  chlorides.  (Filhol.) 

Diy  iodine  cannot  be  made  to  combine  with  5  atoms  of  chlorine 
(Liebig)  ;  iodine  diffused  in  4  parts  of  water  does  not  absorb  much  more 
than  d  atoms  of  chlorine,  and  the  yellow  solution  obtained  yields  a  pre- 
cipitate of  iodine  when  saturated  with  alkalis.  (Soubeiran.])  The  same 
results  are  obtained  when  the  quantity  of  water  is  8  or  1 0  times  as  great 
as  that  of  the  iodine.  If,  however,  the  iodine  be  diffused  through  a  still 
larger  quantity  of  water,  20  parts  for  instance  (Soubeiran),  the  iodine 
combines  with  5  atoms  of  chlorine;  the  solution  in  this  case  is  colourless, 
or  merely  coloured  yellow  from  excess  of  chlorine  which  may  be  removed 
by  a  current  of  air ;  it  exhibits  all  the  properties  of  a  solution  of  hydro- 
chloric acid  and  iodic  acid.  (Liebig,  Soubeiran,  L.  Thompson.) 

I  +  6C1  +  5H0  =  IO»  +  5HC1. 
A  solution  of  the  same  kind  is  obtained  on  mixing  dilute  hydrochloric  and 


350  CHLORIKB. 

iodic  acid.  It  vs  rery  acid,  smellB  slightly  of  chlorine,  aad  slowly  decolor- 
izes solution  of  indigo.  (Gaj-Lussac.^  When  it  is  distilled,  hydrochlo- 
ric acid  passes  over  first ;  bat  as  the  liquid  becomes  more  concentrated,  it 
IS  again  converted  [with  disengagement  of  chlorine  ?]  into  a  yellow  sola- 
tion  of  terchloride  of  iodine  [and  iodic  acid  1].  (L.  Thompson.)  Oil  of 
vitriol  precipitates  terchloride  of  iodine  from  it  (Serullas)  and  liberates 
chlorine.  (Soubeiran.) 

B.  Svlpkate  of  Iodide  of  Sulphur  ^ — 1.  Formed  by  distilling  iodine 
with  sulphite  of  lead.  The  dark  red  distillate  contains  excess  of  iodine. — 
2.  By  dissolving  iodine  in  anhydrous  wood  spirit^  saturating  the  solution 
with  sulphurous  acid  cas^  and  distilling  off  the  wood  spirit  Very  acid  and 
highly  corrosive  liquid.  (Play fair,  Bend.  Jahresher,  20,  Q5,) 


CBLOBmB  AlTD   BrOMINE. 

Chlobidb  of  Bbomikb. 

Formed  when  chlorine  gas  is  passed  through  bromine,  and  the  vapours 
which  escape  condensed  by  a  fic^zinff  mixture.  Beddish-yellow,  veiy 
mobile  and  volatile  liquid ;  emits  dark  yellow  fumes,  having  the  colour 
of  chloric  oxide,  and  a  very  powerful  odour,  and  causing  a  flow  of 
tears.  The  liquid  has  a  hot,  unpleasant  taste.  Metals  bum  in  the  vapour, 
and  are  converted  into  chlorides  and  bromides.  (Balard.) 

Hydrate  of  Chloride  of  Bromine. — 1.  Chlorine  ^  is  passed  through 
bromine  covered  with  water,  whereby  the  bromine  is  first  dissolved  and 
the  liquid  afterwards  converted  into  a  crystalline  mass. — 2.  A  mixture  of 
chloride  of  bromine  and  water  is  cooled  to  a  temperature  below  0°.-^ 
8.  Vapour  of  chloride  of  bromine  is  passed  through  a  moistened  glass  tube 
at  a  temperature  between  0°  and-f-d^. — Light  yellow  coloured  needles  or 
scales,  having  the  same  odour  and  taste  as  chloride  of  bromine.  The 
compound  melts  above  70°  {\5%°  F.),  forming  a  pale  yellow  liquid.  It  is 
rapidly  decomposed  by  ammonia  into  nitrogen  gas,  chloride  of  nitrogen, 
and  hydrobromate  of  ammonia.  (Lowig.) 

Aqueous  9oliUion  of  Chloride  of  Bromine. — 1.  The  yellowish  solution 
has  the  odour  and  the  bleaching  properties  of  anhydrous  chloride  of  bro- 
mine, and  is  resolved  by  fixed  alKsIis  into  metallic  chloride  and  alkaline 
bromate.  (Balard.)     At  a  temperature  below  20°,  it  freezes  to  a  homo- 

feneous  mass ;  when  exposed  to  the  sun*s  rays,  it  is  resolved  into  aqueous 
ydrochloric  and  bromic  acids.  (Lowig.) 

Hydrochloraie  of  Bromine. — Strong  hydrochloric  acid  dissolves  a  large 
quantity  of  bromine,  and  forms  a  solution  having  the  colour,  smell,  and 
taste  of  hydrobromous  acid,  and  like  that  acid,  dissolving  gold.  (Lowig.) 

Bromine  yields  with  Chloride  ofmlphur  a  beautiful  red  coloured  liquid^ 
which  does  not  conduct  electricity  unless  a  small  quantity  of  ether  js 
added  to  it.  (Solly.) 


METALLIC  CHLORIDES.  351 


Other  Compottnds  of  Ghlorinb. 


A.  With  Nitrogen. 

B.  With  the  metals  chlorine  forms  the  Metallic  CfhJorides  (kypotheti- 
edlly  anhydrous  Afuriutes),  CMorures  metalliques  {Muriates  sees,)  Formation 
and  Preparation : — 1.  By  contact  of  a  metid  with  dry  chlorine  gas.  The 
union  of  many  metals  with  chlorine  is  attended  with  development  of  light 
and  heat.  The  following  metals  barn  in  chlorine  gas  at  ordinary  tempera- 
tures. Potassium,  in  mass ;  arsenic,  antimony,  or  bismuth,  in  a  state  of 
powder;  tin,  in  the  form  of  tin-foil,  after  some  time;  Dutch  metal  in  leaf; 
copper  or  nickel,  when  reduced  from  the  oxide  by  hydrogen  gas  to  the  state  of 
finely  divided  metallic  powders.  The  following  bum  when  heated:  sodium, 
tungsten,  manganese,  zinc,  tellurium,  iron,  cobalt,  German  silver,  and 
mercury  (the  latter  when  heated  to  the  boiling  point).  Lead,  silver,  gold, 
and  platinum  unite  indeed  with  chlorine,  but  the  combination  is  not,  at 
any  temperature,  attended  with  evolution  of  light  and  heat.  Bottger 
(Pogg.  43,  660)  passes  chlorine  gas  through  a  chloride  of  calcium  tube,  to 
the  bottom  of  a  pint  or  half-pint  bottle,  till  the  whole  of  the  atmospheric 
air  is  expelled,  and  then  introduces  the  metal  in  the  form  of  a  wire  or  bar, 
a  quarter  of  line  in  thickness,  and  wrapt  up  in  Dutch  foil,  so  that  the 
latter,  when  it  takes  fire  in  the  gas,  may  also  set  fire  to  the  other  metals. 
Treated  in  this  manner,  a  rod  of  antimony  or  bismuth  (obtained  by  running 
the  fused  metal  into  a  glass  tube)  becomes  red-hot,  runs  down  in  drops, 
and  bums  with  a  brilliant  white  light  and  emission  of  sparks.  A  well 
hardened  watch-spring  wound  in  a  spiral  form,  bums  with  incandescence, 
and  produces  a  dense  brownish  red  cloud :  a  finer  spring  emits  a  more 
brilliant  light  and  a  shower  of  sparks.  Very  fine  copper  wire  becomes 
red-hot,  but  bums  without  emission  of  sparks.  Brass  wire  bums  com- 
pletely, with  the  most  abundant  emission  of  sparks.  German  silver  wire 
becomes  white  hot,  and  throws  off  melted  drops  which  burst  with  a  splen- 
did light.  Wires  of  zinc,  cadmium,  lead,  fusible  metal,  nickel,  silver, 
gold,  platinum,  or  palladium,  cannot  be  inflamed  in  this  manner.  (Bottger.) 
A  feebly  ignited  copper  wire  bums  completely  in  chlorine  gas,  yielding 
dichloride  of  copper  m  fused  drops.  (Wbhler,  nerzeL  Jahresher.  19,  215.) 
— 2.  Chlorine  gas  decomposes  a  great  many  metallic  oxides,  sometimes 
even  at  ordinary  temperatures  {e.  g,  oxide  of  silver)  sometimes  with  the 
aid  of  heat  (as  the  fixed  alkalis),  the  products  being  metallic  chloride  and 
oxygen  gas.  In  these  cases,  one  volume  of  oxygen  is  usually  set  free  for 
every  two  volumes  of  chlorine  absorbed.  The  above  decomposition  takes 
place  when  the  affinity  of  the  chlorine  for  the  metal  -{-  that  of  the  oxygen 
for  heat  is  greater  than  the  affinity  of  the  oxygen  for  the  metal  +  that 
of  heat  for  chlorine.  {Sck.  8.)— 3.  Many  metals,  either  at  ordinary  tem- 
peratures, or  at  a  rea  heat,  or  when  aided  by  the  passage  of  electric 
sparks,  convert  hydrochloric  acid  gas  into  metallic  chloride  and  a  half- 
volume  of  hydrogen  gas  {p.  321). — 4.  Most  metallic  oxides  by  contact 
with  hydrochloric  acid,  yield  metallic  chlorides  and  water  (/>.  321). — 
5.  Many  metallic  oxides,  when  mixed  with  charcoal  and  heated  to  red- 
ness in  a  tube,  are  resolved,  by  a  current  of  chlorine,  into  metallic  chlo- 
rides and  carbonic  oxide  or  carbonic  acid.  (Gay-Lussac  &  Th^nard, 
Recherches,  2,  143;  Oerstedt,  Pogg.  5,  132.)  This  method  is  especially 
adapted  to  the  preparation  of  the  compounds  of  chlorine  with  the  earth- 
metals.  To  obtain  metallic  chlorides  in  large  quantity  by  this  process, 
Quesneyille  («/.  Pharm.  15,  328;  also  Sckw.  56,  873)  ignites  the  mixtare 


352  CHLORINE* 

of  metallic  oxide  and  charcoal  in  a  tubulated  earthen  retort  instead  of  a 
porcelain  tube,  and  paases  the  chlorine  into  the  mixture  through  a  tube 
which  fits  into  the  tubulure  of  the  retort.  When  the  chloride  is  liquid,  he 
receives  it  in  a  Woulfe's  bottle  connected  with  the  neck  of  the  retort  by 
means  of  a  bent  tube^funnel;  and  when  it  is  solid,  in  a  glass  globe  which 
runs  out  at  the  bottom  into  an  elongated  point,  and  has  an  opening  abore 
and  two  openings  at  the  sides;  through  one  of  the  side  openings  the  neck 
of  the  retort  enters;  the  opposite  opening  serves  for  the  passage  of  an  iron 
wire  to  clear  out  the  neck  of  the  retort  when  stopped  up  with  the  metallic 
chloride. — 6.  Metallic  chlorides  are  formed  in  the  various  decompositions 
of  hypochlorites,  chlorites,  chlorates,  and  perchlorates. — 7.  One  metallic 
chloride  may  be  converted  into  another  by  the  action  of  single  or  double 
affinity.  Chloride  of  mercury  yields  with  antimony :  chloride  of  antimony 
and  metallic  mercury;  and  with  sulphide  of  antimony :  chloride  of  anti- 
mony and  sulphide  of  mercury.  (Sch.  45.) 

Some  metallic  chlorides  are  liquid  at  ordinary  temperatures ;  and  these 
are  very  volatile:  MHcUlic  oils  (the  chlorides  of  tin,  arsenic,  antimony); 
some  are  solid,  though  at  the  same  time  very  fusible,  and  generally  vola- 
tile at  a  red  heat;  the  softer  of  these  are  called  Metallic  butters  (the  chlo- 
rides of  antimony,  bismuth,  zinc)  the  more  solid,  Uom-metals  {e.g.  horn- 
silver,  horn-lead.)  Those  metallic  chlorides  which  are  not  decomposed  by 
heat,  are,  almost  without  exception,  more  volatile  than  the  metals  from 
which  they  are  formed. 

A  few  metallic  chlorides,  when  ignited  out  of  contact  of  air,  are 
resolved  into  metal  and  chlorine  gas  (the  chlorides  of  gold  and  platinum). 
Some  give  up  only  a  portion  of  their  chlorine  (protochloride  of  copper). 
Others  again  are  not  decomposed  by  simple  ignition ;  but  when  ignited  in 
the  air,  are  resolved  into  metallic  oxides  and  chlorine  ffas  (such  is  the  case 
with  the  chlorides  of  manganese  and  iron ;  the  chlorides  of  barium,  stron- 
tium, and  calcium  are  also  to  a  very  small  extent  converted  into  oxides 
by  this  treatment.)  Most  chlorides  remain  undecomposed  in  either  case. 
Metallic  chlorides  which  are  not  decomposed  by  heat  alone,  likewise  resist 
the  action  of  charcoal  at  a  white  heat,  oecause  carbon  does  not  form  any 
inorganic  compound  with  chlorine.  (Inasmuch,  however,  as  the  charcoal 
usually  contains  a  small  quantity  of  hydrogen,  a  small  portion  of  the 
chloride  may  be  converted,  at  the  beginning  of  the  action,  into  metal  and 
hydrochloric  acid.)  But  as  soon  as  the  ignited  mixture  is  brought  in  contact 
with  aqueous  vapour,  the  oxygen  of  which  has  considerable  affinity  for  the 
charcoal,  and  the  hydrogen  lor  the  chlorine,  decomposition  takes  place, 
-^mz,,  with  the  chlorides  of  silver  and  mercury — into  carbonic  acid  or  car- 
bonic oxide,  hydrochloric  acid,  and  metal.   (Gay-Lussac  &  Th^nard.) 

{Sch.  mi 

AgCl  +  HO  +  C  =  Ag  +  HCl  +  CO. 
The  contrary  results  obtained  by  Lampadius,  which  do  not  accord  with 
any  theory  {Gilh,  73, 143),  maybe  attributed  to  the  porosity  of  the  earthen 
retorts  which  he  used,  and  indeed  arc  altogether  refuted  by  Dobereiner's 
experiments.  {Gilh,  73,  227.)  No  metallic  chloride  is  decomposed  by 
heating  with  sulphur;  phosphorus,  on  the  contrary,  separates  the  chlo- 
rine from  several  of  these  compounds.  (H.  Rose,  Pogg.  27,  116.) 

Those  metallic  chlorides  which  are  not  decomposed  by  heat  alone,  e,  g, 
the  chlorides  of  the  alkali-metals,  silver  and  mercury,  likewise  resist 
decompositiou  when  heated  to  whiteness  (in  the  absence  of  moisture)  with 
vitrefied  boracic  acid,  vitrefied  phosphoric  acid  containing  lime,  or  with 
silica,  glucina,  or  alumina — substances  which,  though  they  have  more  or 


METALLIC  CHLOftlDES.  353^ 

less  dffinitj  for  metallic  oxides,  have  no  affinity  for  the  luetals  themselves, 
or  for  chlorine.  As  soon,  hoTV  ever,  as  aqueous  vapour  comes  in  contact 
with  the  ignited  mixture,  its  oxygen  combines  with  the  metal,  forming  a 
metallic  oxide,  which  is  taken  up  by  the  above  mentioned  acids  or  earths, 
and  the  h^dro^en  of  the  water  escapes  in  union  with  the  chlorine,  as 
hydrochloric  acid  gas.  (Ghty-Lnssac  &  Thenard,  Davy.)  (Sch.  58.) 

Naa  +  HO  +  nSiO»  =  NaO,  nSiOt  +  HCL 
But  when  the  vapour  of  anhvdrous  sulphuric  acid — ^which  retains  its  oxy- 
gen less  forcibly  than  boracic  or  phosphoric  acid — is  passed  over  ignited 
common  salt,  sulphate  of  soda  is  formed,  and  a  mixture  of  equal  volumes 
of  chlorine  and  sulphurous  acid  gas  is  evolved.  (Sch.  74.) 

NaCl  +  2S0»  =  NaO,  S0»  +  S0«  +  CI. 
The  very  light  yellow-coloured  gaseous  mixture  which  escapes,  is  absorbed 
by  water  in  the  form  of  hydrochloric  and  sulphuric  acids,  one  atom  of 
chlorine  taking  one  atom  of  hydrogen  from  the  water,  and  the  atom  of 
oxygen  thus  set  free  being  taken  up  by  the  sulphurous  acid.  Hence 
Sertiimer  concluded  that  hydrochloric  acid  exists  already  formed  in  the 
gaseous  mixture.  (Fief.  Sertiimer,  Gilb^  72,  109;  73,213; — Dobereiner, 
Glib.  72,  33l;--C.  G.  Gmelin.  Schw.  37,  442;— L.  Gmelin,  GUb,  73, 
109.)  Nitric  acid  likewise  disengages  chlorine  from  many  metallic  chlo- 
rides, inasmuch  as  it  oxidizes  the  metals,  and  then  combines  with  the 
metallic  oxide  formed. 

Hydrated  boracic,  phosphoric,  sulphuric  and  arsenic  acid,  decompose 
most  metallic  chlorides,  sometimes  at  ordinal^  temperatures,  sometimes 
with  the  aid  of  heat,  the  products  being  hydrochloric  acid  and  a  com- 
pound of  the  metallic  oxide  with  the  oxygen  acid.  The  compounds  of  the 
light  metals, — manganese,  zinc,  tin,  iron,  and  cobalt — with  chlorine,  are 
decomposed  by  oil  of  vitriol,  even  at  ordinary  temperatures;  those  of 
antimony,  bismuth,  and  copper,  only  with  the  aid  of  heat.  (A.  Vogel.) 
Protochforide  of  meicnry  is  not  decomposed  at  any  temperature.  Metallic 
chlorides  when  mixed  with  peroxide  of  manganese  or  peroxide  of  lead, 
and  heated  with  oil  of  vitriol,  evolve  chlorine  gas  ;  and  when  mixed  with 
chromate  of  potash  and  distilled  with  oil  of  vitriol,  they  yield  a  dark 
bluisli  red  distillate  of  chromate  of  terchloride  of  chromium.  A  bead  of 
microcosmic  salt  nearly  saturated  with  oxide  of  copper,  imparts  a  blue 
colour  to  the  blow-pipe  flame  on  the  addition  of  a  metallic  chloride.  (Ber- 
zelius.) 

Hydrated  Metallic  Chloridet  or  HydroMoroUs  (jOhlorwauertiioffMure 
Salze,  Muriates,  Chlorkydrates). 

All  metallic  chlorides  are  soluble  in  water,  excepting  chloride  of  silver, 
dichloride  of  copper,  dichloride  of  mercury,  protochloride  of  gold,  and 
protochloride  of  platinum.  These  solutions  may  be  regarded  either  as 
aqueous  metallic  chlorides  or  as  aqueous  hydrochlorates  of  metallic  oxides. 
The  same  solutions  are  obtained  by  treating  metallic  oxides  with  aqueous 
hydrochloric  acid,  and,  in  many  cases,  by  treating  a  metal  with  aqueous 
hydrochloric  acid,  hydrogen  gas  being  evolved. 

Zn  +  HCl  =  ZnCl  +  H 
or:  Zn  +  HO  +  HCl  =  ZnO,  HCl  +  H. 

Further,  by  treating  many  metals  with  a  mixture  of  aqueous  hydrochloric 
and  nitric  acids. 

3Cu  +  3HC1  +  NO*  =  3CuCl  +  SHO  +  N0«; 
or:  3Cu  +  3HC1  +  NO*  =  3(CuO,  HCl)  +  NO*. 
VOL.  II.  2  a 


354  GHLORIKB. 

ffheee  soluiioiui  when  cooled  and  emporated,  depoait  either  uihydroiifl 
metallic  chlorides  (as  in  the  case  of  chloride  of  sodinm)  or  hjdrated  crys- 
tals, which  may  be  regarded  as  hjdrated  metallic  chlorides  or  as  salts  of 
hydrochloric  acid :  they  generally  also  contain  an  additional  quantity  of 
water.  Thus,  chloride  of  barium  crystallises  from  an  aqueons  solution  in 
the  form  of  BaCl  +  2HO=:BaO,  HCl  +  HO;  chloride  of  calcium  crys- 
tallizes with  six  atoms  of  water,  (CaCl  +  6HO=CaO,  HCl  +  «5H0.)  These 
hydrated  crystals,  when  stronely  heated,  either  give  off  water  and  are 
converted  into  metallic  chlorides,  or  they  evolve  hydrochloric  acid  and 
leave  metallic  oxides :  such  is  the  case  with  a  solution  of  magnesia  or 
alumina  in  hydrochloric  acid. — (On  the  question,  whether  the  metallic 
chlorides  are  converted  into  hydrochlorates  or  not,  in  contact  with  water, 
vid.  pp.  10 — 13.)  H.  Rose  {rogg.  55,  533,)  is  of  opinion  that  the  mode 
of  action  varies  with  the  nature  of  the  chloride.  According  to  Rose, 
a  metallic  chloride  dissolves  without  alteration,  when  the  metal  which  it 
contains  is  capable  of  forming  a  salifiable  base  with  oxygen  (the  alkali- 
metals,  mercury,  &c.);  on  the  contrary,  it  dissolves  in  the  form  of  hydro- 
chlorate  of  the  oxide,  when  the  latter  has  a  more  acid  character  (silicium, 
titanium,  tin,  arsenic,  antimony  and  bismuth).  The  solntion  of  the  former 
class  of  metallic  chlorides  is  generally  attended  with  production  of  cold, 
that  of  the  latter,  always  with  evolution  of  heat;  and  by  this  character 
the  two  classes  of  metallic  chlorides  may  be  distinguished  from  each  other, 
a  few  cases  only  excepted.  Against  this,  the  advocates  of  the  theory  of 
hydrogen  salts  of  metallic  oxides  may  allege: — 1.  That  the  metallic  chlo- 
rides of  the  former  class  are  precisely  those  which,  d  priori,  may  be  ex- 
pected to  be  most  easily  decomposed  by  water,  inasmuch  as  that  class 
includes  the  very  metals  whose  affinity  for  oxygen,  [but  at  the  same  time, 
also,  for  chlorinej  is  the  greatest:  moreover,  the  predisposing  affinity  of  the 
salifiable  oxide  for  hydrochloric  acid,  and  mce  wrsd,  may  oe  expected  to 
facilitate  the  formation  of  these  compounds. — 2.  That  when  the  affinity  of 
chlorine  for  the  metal  +  that  of  hydrogen  for  oxygen  is  nearly  equal  to  the 
affinity  of  the  metal  for  oxygen  +  that  of  chlorine  for  hydrogen  +  that  of 
the  metallic  oxide  for  hydrochloric  acid,  decomposition  takes  place  attended 
with  slight  evolution  of  heat;  but  the  rise  of  temperature  thus  produced 
is  more  than  counterbalanced  by  the  heat  which  is  rendered  latent  in  the 
passage  of  the  solid  substance  to  the  liquid  state  (as  with  common  salt). 
Ob  the  other  hand,  the  more  the  latter  sum  of  affinities  exceeds  the  former 
— the  more,  that  is  to  say,  the  affinity  of  a  metal  for  oxygen  exceeds  its 
affinity  for  chlorine— the  greater  will  be  the  rise  of  temperature  produced 
by  its  solution.  Rose  enumerates  chloride  of  calcium  among  the  metallic 
chlorides  which  are  not  decomposed  by  solution,  notwithstanding  that  it 
evolves  great  heat  by  contact  with  water  ;  and  explains  this  anomaly  by 
supposing  that  the  first  atoms  of  water  combine  more  intimately  with  the 
salt,  in  the  form  of  water  of  crystallization.  But  if  this  explanation  is 
to  be  admitted  as  satisfactory,  and  especially  if  it  is  to  extend  to  those 
cases  in  which,  by  the  use  of  a  larger  quantity  of  water,  the  mixture  is 
TCtained  in  the  liquid  state  and  prevented  from  crystallizing,  the  appli* 
cation  of  change  of  temperature  to  determine  whether  a  metallic  chloride 
is  or  is  not  decomposed  by  solution  in  water — even  supposing  the  theory 
to  be  well  founded — will  be  reduced  within  very  narrow  limits. 

Aqueous  solutions  of  metallic  chlorides  precipitate  chloride  of  lead 
from  lead-salts  moderately  concentrated,  dichloride  of  mercuiy  from 
mercurouB  salts,  and  chloride  of  silver  from  silver  salts,  even  when 
largely  diluted  :  the  precipitates  are  white.   Chloride  of  silver  and  dichlo- 


IIETAUIG  CHLOBIDBS.  855 

ride  of  meronry^  wben  precipitated  from  solutions  somewhat  concentrated, 
assume  a  curdy  form ;  when  the  liquid  is  much  diluted,  thej  produce  a  milky 
opalescence.  Chloride  of  silver  acquires  a  riolet  tint  when  exposed  to  light ; 
it  is  insoluble  in  dilute  nitric  acid,  but  ammonia,  even  when  dilute,  dissolves 
it  readily  (thereby  distinguished  from  iodide  or  bromide  of  silver).  If  com- 
mon salt  be  dissolved  in  such  quantities  of  water,  that  one  part  of  chlorine 
shall  be  contained  in  the  following  quantities  of  liquid,  the  different  solutions 
exhibit  the  annexed  reactions  with  nitrate  of  mercurous  oxide  and  nitrate  of 
silver :  50,000  parts  of  water :  with  mercury,  pulverulent  precipitate ;  with 
silver,  slight  milky  turbidity ;  100,000  parts  of  water:  mercury,  slight 
precipitate ;  silver,  slight  turbidity ; — 200,000  parts  of  water :  mercury, 
turbidity  after  a  few  minutes;  silver,  immediate  slight  cloud; — 400,000 
parts  of  water:  mercury,  very  slight  turbidity  after  some  minutes; 
silver,  very  slight  turbidity ;— 800,000  parts  of  water :  mercury,  opales- 
cence after  some  time ;  silver,  very  feint  opalescence ; — 1 ,600,000  parts 
of  water:  mercury,  scarcely  preceptible  opalescence  after  some  time; 
silver,  scarcely  perceptible  opalescence.  "With  solution  of  sal-ammoniac, 
the  silver  solution  behaves  in  a  similar  manner,  and  gives  a  barely  percep- 
tible cloud,  even  with  3,200,000  parts  of  water;  with  mercury,  however, 
the  reaction  ceases  with  400,000  parts  of  water  to  one  part  of  chlorine. 
(Lassaigne,  J.  Chim,  med.  8,  518.)  A  mixture  of  a  metallic  chloride  with 
sulphate  of  copper  dissolved  in  water,  gradually  blackens  a  polished 
plate  of  silver. 

Some  metallic  chlorides  (e.  g,  the  chlorides  of  ammonium,  potassium, 
and  sodium)  combine  with  terchloride  of  iodine.  (For  the  preparation  of 
these  compounds,  see  more  especially  the  chapter  on  Potassium.)  They 
may  be  regarded  as  chlorine  salts,  in  which  the  terchloride  of  iodine  plays 
the  part  of  an  acid,  e,  g.  KCl,  ICK 

Some  metallic  chlorides  combine  with  hydrochloric  acid.  Thus,  the 
dichloride  of  copper,  which  is  insoluble  in  water,  dissolves  in  strong  hydro- 
chloric acid  ;  and  corrosive  sublimate  is  much  more  soluble  in  hydrochloric 
acid  than  in  water.  These  compounds  may  be  considered  either  as 
chlorine-salts,  in  which  the  hydrocnluric  acid  is  the  acid  and  the  metallic 
chloride  the  base ;  or,  according  to  the  other  theory  (since  water  is  pre- 
sent), as  acid  hydrochlorates  of  metallic  oxides. 

Some  metallic  chlorides  are  capable  of  uniting  with  the  oxides  of  the 
same  metals:  Oxychlorides,  Oxychlorures,  e.  g,  CrCP,2CrO', — 3PbO, 
PbCl,  and  SSbO*,  SbCl'.  (or  as  more  recently  determined  by  Malaguti 
and  Johnston,  9SbO%2SbGR)  When  water  is  added  to  these  com- 
pounds, hydrated  oxychlorides — or,  according  to  the  other  view — basic 
hydrochlorates  of  the  oxides,  are  produced.     Thus,  atacamite  is : 

3CuO,  CuCl  +  4H0  or  4CuO,  HCl  +  3H0. 

Many  metallic  chlorides  combine  with  each  other :  Metallic  Chlorine 
salts. — For  instance,  the  chlorides  of  mercury,  platinum,  and  gold,  and 
other  electro-negative  chlorides,  combine  with  the  chlorine  compounds  of 
the  alkali-metals  and  other  positive  metals.  In  these  compounds,  Bons- 
dorff  regards  the  chloride  of  mercury,  &c.,  as  the  acid,  and  the  chloride 
of  potassium,  &c.,  as  the  base.  According  to  the  same  authority,  the 
aqueous  solutions  of  the  chlorides  of  calcium,  magnesium,  manganese  and 
zinc,  turn  logwood  blue  and  are  therefore  of  a  basic  nature;  the  chlorides 
of  barium  and  strontium  give  the  same  reaction  in  a  slight  degree; 
chloride  of  potassium  and  chloride  of  sodium,  not  at  all.  (Bonsdorff.) 
Compare  the  contrary  observations  of  H.  Rose  {Pogg  55,  552). 

2  A  2 


t^5G  CHLORINE. 

Many  metallic  chlorides  are  capable  of  uniting  witb  ammonia  in 
definite  proportions. 

Many  again  are  soluble  in  alcohol,  ether,  volatile  oils,  &c.  and  a  few 
are  capable  of  entering  into  organic  compounds. 

Anticbloristic  Theory. 

Lavoisier's  discovery,  that  most  acids  contain  oxygen,  led  to  the  sup- 
position, that  the  acids  which,  up  to  that  time,  had  not  been  decomposed 
—muriatic  acid,  for  example— derived  their  acid  properties  from  the  pre- 
sence of  the  same  element.  Muriatic  acid  was  therefore  regarded  as  a 
compound  of  oxygen  with  the  unknown  radical,  Muriatum,  or  Murium; 
and  chlorine,  or  oxygen ised  muriatic  acid,  was  supposed  to  contain  the 
same  radical  united  with  a  larger  quantity  of  oxygen.  This  so-called 
muriatum,  however,  could  not  be  isolated.  Moreover,  it  was  found  that 
the  dryest  muriatic  acid  gas,  when  brought  in  contact  with  red-hot  metals, 
evolves  a  large  quantity  of  hydrogen ;  and  that  1  volume  of  dry  chlo- 
rine gas  with  1  volume  of  dry  hydrogen  forms  two  volumes  of  perfectly 
dry  muriatic  acid  gas.  From  these  two  facts  it  was  concluded  that  1 
volume  of  chlorine  (or  oxymuriatic  acid)  gas  contains  a  half  volume  of 
oxygen,  which,  in  the  formation  of  muriatic  acid  gas,  combines  with  1  volume 
of  hydrogen ;  and  that  muriatic  acid  gas  is  an  intimate  compound,  in 
equal  numbers  of  atoms,  of  water  and  a  not  yet  isolated  anhydrous  muri- 
atic acidy  which  may  be  called  hypatheticaUy  anhydrous  muriatic  acid,  to 
distinguish  it  from  ordinary  dry  or  anhydrous  muriatic  acid  gas.  Berze- 
zelius  formerly  arranged  the  various  degrees  of  oxidation  in  the  series  as 
follows : 

1  At.  Murium 

=  1 1  *4,  talces  up  And  forms 

of  Oxygen:  therewith:  Antichlorigtic  Nam$9,         ChhrUHc  Nameg. 

At. 

2  =  16  27*4  Hyp.  Anhyd.  Muriatic  acid 

3  =  24  35'4  Oxymuriatic  acid Chlorine. 

4  =  32  43*4  Euchlorine    Chlorous  oxide. 

G  =  48  59-4  ?  Chloric  oxide. 

8  =  64  75*4  Hyperoxymuriatic  add Chloric  add. 

10  =  80  91-4  ?  Perchloric  add. 

Muriatic  acid  gas  is  a  compound  of  1  At.  hypothetically  anhydrous  mu- 
riatic acid  =  27-4,  with  1  At.  water  =  0,  making  together  36-4  (MuO*  + 
HO).  Charcoal  cannot  decompose  the  water  contained  in  muriatic  acid 
gas,  not  even  at  a  white  heat,  because  the  great  affinity  of  hyp.  anhy- 
drous muriatic  acid  for  the  water  protects  it  from  decomposition.  Nei- 
ther can  charcoal  withdraw  from  oxymuriatic  acid  (MuO^j  its  third  atom 
of  oxygen ;  because  the  oxygen  has  a  stronger  affinity  for  hyp.  anhy- 
drous muriatic  acid  than  for  carbon.  Phosgene  ^as  is  a  compound  of  hyp. 
anhydrous  muriatic  acid  with  carbonic  acid  (MuO,  CO^)j  in  this  case, 
carbonic  oxide  is  able  to  abstract  the  third  atom  of  oxygen  from  oxymu- 
riatic acid,  and  form  carbonic  acid,  because  the  affinity  of  hyp.  anhy- 
drous muriatic  acid  for  carbonic  acid  is  likewise  very  great.  Our  ter- 
cbloride  of  phosphorus  is  hypothetically  dry  muriate  of  phosphorous  acid 
(PO',  3MuO*);  pentachloride  of  phosphorus  is  hyp.  anhydrous  muiiate 
of  phosphoric  acid  (PO*,  5MuO').  The  phosphorus  burns  in  the  third 
atom  of  oxygen  of  the  oxymuriatic  acid  gas,  forming  phosphorous  or 
phosphoric  acid,  which  then  enters  into  intimate  comoination  with  the 
separated  anhydrous  muriatic  acid.      Similarly,    the  two  chlorides  of 


ANTICHLORISTIC  THEORY.  357 

sulphur  may  be  regarded  as  compounds  of  hyp.  anhydrous  muriatic  acid 
with  hyposulphnrous  acid  and  another  lower  oxide  of  sulphur,  not  yet 
isolated,  containing  2  At.  S  and  1  At.  0.  In  the  same  manner,  also,  the 
oxychloride  of  bisulphide  of  carbon  is  to  be  regarded  as  a  compound  of 
2  At.  hyp.  anhydrous  muriatic  acid  with  1  At.  carbonic  acid  and  1  At. 
sulphurous  acid  (CO*,  SO',  MuO*).  Water  decomposes  these  compounds 
by  converting  the  hyp.  anhydrous  muriatic  acid  into  muriatic  acid  gas, 

nvlvl^l.     Lm^    _.     1 —  11*  _  *X f ^1 V^A . - 1_     _~_l.^..^J 


a  compound  of  hjp.  anhydrous  muriatic  acid  with  nitrous  acid  (NO', 
8MuO*).  Metallic  chlorides  are  hyp.  anhydrous  muriates  of  metallic 
oxides ;  for  the  metal,  when  immersed  in  oxymuriatic  gas,  bums  in  its 
third  atom  of  oxygen  and  is  converted  into  an  oxide,  which  then  com- 
bines with  the  remaining  hyp.  anhydrous  muriatic  acid  and  forms  a 
hyp.  anhydrous  muriate  of  that  oxide.  The  same  compounds  are  formed 
when  various  metallic  oxides  are  brought  in  contact  with  oxymuriatic 
acid  gas,  the  third  atom  of  oxygen  then  escaping  in  the  form  of  gas  and 
the  remaining  hyp.  anhydrous  muriatic  acid  combining  with  the  oxide. 
A  hyp.  anhydrous  metallic  muriate  may  also  be  formed,  with  evolution  of 
hydrogen,  by  contact  of  a  metal  with  muriatic  acid  gas,  the  oxidation 
being  in  this  case  produced  by  the  water  contained  in  the  muriatic  acid 
gas.  Lastly,  when  muriatic  acid  gas  is  brought  in  contact  with  oxide  of 
lead,  the  water  contained  in  the  gas  is  set  at  liberty,  and  the  hyp.  anhy- 
drous muriatic  acid  combines  with  the  oxide  of  lead :  the  water  is  an 
educt,  according  to  the  antichloristic  theory;  whereas  according  to  the 
chloristic  theory  it  is  a  product.  No  other  acid  has  so  great  an  affinity 
for  metallic  oxides  as  muriatic  acid;  and  therefore  its  salts  resist  the 
decomposing  action  of  all  other  acids  (of  boracic  acid,  at  a  red  heat,  for 
example) ;  but  if  water  is  present,  decomposition  takes  place ;  because 
hyp.  anhydrous  muriatic  acid  has  likewise  a  great  affinity  for  that  sub- 
stance, so  that  the  affinity  of  the  foreign  acid  for  the  metallic  oxide,  toge- 
ther with  the  affinity  of  the  hyp.  anhydrous  muriatic  acid  for  the  water, 
overcomes  the  affinity  of  the  hyp.  anhydrous  muriatic  acid  for  the  metallic 
oxide.  Common  salt  is  decomposed  by  sulphuric  acid,  because  the 
affinity  of  the  hyp.  anhydrous  muriatic  acid  for  the  oxygen  of  a  por- 
tion of  the  sulphuric  acid,  together  with  the  affinity  of  the  soda  for 
the  remaining  portion  of  that  acid,  is  greater  than  the  affinity  of  the 
hyp.  anhydrous  muriatic  acid  for  the  soda»  together  with  that  of  the 
sulphurous  acid  for  the  third  atom  of  oxygen.  Charcoal  does  not  decom- 
pose the  hypothetically  anhydrous  muriates,  because  the  greater  affinity 
of  hyp.  anhydrous  muriatic  acid  for  the  metallic  oxide->oxide  of  silver, 
for  example — protects  the  oxide  from  the  decomposing  action  of  the  char- 
coal ;  but  if  vapour  of  water  is  also  present,  so  that  the  hyp.  anhydrous 
muriatic  acid  can  combine  with  it  and  form  muriatic  acid  gas,  the  char* 
coal  is  then  able  to  deprive  the  metallic  oxide  of  its  oxygen  and  form 
carbonic  acid. 

The  formation  of  a  muriate  and  hjrperoxymuriate  (chlorate)  of  an 
alkali,  when  oxymuriatic  acid  comes  in  contact  with  the  aqueous  solution 
of  an  alkali,  is  effected  by  5  atoms  of  oxymuriatic  acid  giving  up  their 
third  atom  of  oxygen  to  a  sixth  atom  of  oxymuriatic  acid,  which  is 
thereby  converted  into  hyperoxymuriatic  acid. 

This  system  is  more  uniform  than  the  modern  CMaristic  Theory,  inas- 
much as  it  supposes  that  all  acid  and  basic  substances  contain  oxygen — 


S58  CHLORINE^ 

which  howeyerifl  not  the  case  with  the  hjdrosulphario,  hydroteUiirii;, 
hydrocyanic,  and  other  undoubted  hydrogen-acids.  Moreover,  the  theory 
assumes  the  existence  of  two  substances  which  are  purely  hypothetical 
and  cannot  be  obtained  in  the  separate  state,  viz.,  muHum  and  hypo- 
thetically  anhydrouz  muriatic  acid.  Both  theories,  however,  admit  of 
being  consecutively  carried  out ;  and,  however  opposed  they  may  be  to 
each  other,  neither  of  them  is  contradicted  by  a  single  direct  experiment 
But  the  chloristic  theory  is  by  far  the  simpler  of  the  two,  and  more  sup- 
ported by  analogy  than  the  antichloristic.  (For  the  arguments  formerly 
adduced  by  Berzeiius  in  favour  of  the  antichloristic  theory,  vid,  GHh,  50, 
356;  9,160  Schw.  14,66.) 

Berzeiius  applied  the  same  views  to  iodine  as  to  chlorine,  regarding 
iodine  as  a  compound  of  an  acid-radical  with  3  atoms  of  oxygen.  He 
assumed  1 02  as  the  atomic  weight  of  the  iodine-radical ;  and  supposed 
that  this  radical,  in  combination  with  2  atoms  of  oxygen  =:  16^  formed 
hypothetically  anhydrou$  hydriodic  acid,  which,  by  taking  up  an  atom  of 
water  =  9,  is  converted  into  hydriodic  acid  gas;  102  iodine- radical  conibinei 
with  3*8  =  24  oxygen  to  /orm  iodine,  and  with  8*8  =  64  oxygen  to 
form  iodic  acid.  Iodide  of  phosphorus  and  iodide  of  sulphur  would, 
according  to  the  same  theory,  be  regarded  as  compounds  of  hypothetically 
anhydrous  hydriodic  acid  with  certain  oxides  of  phosphorus  and  sulphur; 
and  the  metallic  iodides,  as  compounds  of  hypothetically  anhydrous  hydri- 
odic aoid  with  metallic  oxides. 


Chapter  XI. 

FLUORINE. 


Scheele,  Opu9e.  2,  1  and  242;  CrdL  Chem.  J.  2,  192,  and  GreU.  Ann. 

1786,  1,  3. 
Wiegler,  Crell,  N.  EntdecL  1,  3. 
Biicholz.  Crell.  N.  Entdeck.  3,  50. 
Gay-Lussac  &  Th^nard,  Eeckerches,  2,  1 ;  also  Ann.  Ohim.  69,  204;  also 

K  Gehl,  8,  485;  also  Gilb.  32,  1. 
Sir  H.  Davy,  FhU.  Trans.  1809;  also  Schw.  2,  57;  also  Gilb,  35,  452,— 

Phil.  Tram.  1813,  263;  also  Ann.  Ckim.  88,  271. 
J.  Davy,  Fhil.  Trans.  1812,  352;  also  Ann.  Chim.  86,  178. 
Berzeiius,  Fogg,  1,  1  and  169;  2,  111;  4,  1  and  117. 
Otto  Unverdorben,  N.  Tr,  9,  1,  22. 


Hiitory.  The  process  of  etching  on  glass  with  fluor-spar  was  known 
to  Schwankhard,  of  Nuremberg,  as  early  as  1670.  Marggraf,  in  1764, 
observed  that  a  glass  retort  in  which  he  had  heated  fluorspar  with  sul- 
phuric aoid  was  corroded,  and  a  white  sublimate  formed.  Scheele,  in 
1771;  first  discovered  that  fluor-spar  is  a  compound  of  lime  with  a  pecu- 
liar acid ;  he  likewise  prepared  that  acid  from  it,  both  in  the  state  of 
aqueous  solution,  by  using  a  tin  retort  to  distil  it,  and  likewise  in  the 
-  form  of  gaseous  fluoride  oi  silicinm;  but  Priestley  was  the  first  who  ooi- 
leeted  that  £as  over  mercury.  Ga3r-Lus6ac  &  Thtoavd,  in  1808,  first 
prepared   anhydrous  hydrofluoric  aoid   and   discovered    fluoboric  gas. 


FLUORINE.  S59 

John  Dayy,  in  1812,  inyestigated  various  relations  of  flnoride  of  boron 
and  fluoride  of  siliciam.  Up  to  that  time,  hydroflnoric  acid  had  been 
regarded  as  a  compound  of  oxjgen  with  an  unknown  combustible  base. 
Fluoriunif  which  Gay-Lussao  &  Thenard  and  Sir  Humphry  Davy  in 
yaiu  endeavoured  to  separate  from  fluosilicic  acid  gas  by  means  of  potas- 
sium. Ampere,  in  1810,  first  applied  the  chloristic  theory  to  the  relations 
of  hydrofluoric  acid,  considering  that  acid  as  a  compound  of  hydrogen 
with  an  unknown  BuhBtsbuoe,.  fluorine,  and  fluor-spar  as  a  fluoride  of  cal- 
cium. This  theory  was  supported  by  Sir  Humphry  Davy  by  a  variety 
of  experiments,  and  adopted  by  him  and  by  many  other  chemists.  Finally, 
in  1824,  the  chemical  nistory  of  the  fluorine  compounds  was  greatly 
extended  by  the  comprehensive  researches  of  Berzelius. 

Sources.  Not  abundant:  found  chiefly  in  fluor-spar;  also  in  fluoride 
of  cerium,  basic  hydrofluate  of  cerium,  topaz,  ciy elite,  warwickite,  and 
yttrocerite ;  and  in  small  quantities  in  fluor-apatite,  wagnerite,  amblygo- 
nite,  wavellite,  leucophaue,  lepidolite,  many  kinds  of  mica  and  apophyl- 
lite,  in  carpholite,  chondrodite,  hornblende,  and  pyrochlor.  According 
to  Breithaupt  and  Harkort  {Pogg.  9,  179),  it  likewise  occurs  in  felspar 
and  the  allied  minerals.  Moreover,  in  bones,  teeth,  and  human  urine. 
The  late  remarkable  assertion  of  Bees  {Phil.  Mag.  J.  15,  459,)  that  human 
bones,  the  enamel  of  the  teeth,  and  ivory,  do  not  contain  fluorine  has  been 
refuted  by  Erdman.   {J.  pr.  Chem.  19,  446.) 

Of  fluorine  in  the  separate  state  we  know  but  little;  its  property  of 
corroding  vessels  of  almost  eveiy  description  renders  its  separation  a 
matter  of  great  difliculty.  The  following  are  the  attempts  which  have 
hitherto  been  made  to  eflect  the  preparation  of  pure  fluorine. 

The  fluorides  of  potassium,  sodium,  mercury,  and  silver,  may  be  de- 
composed by  chlorine;  but  if  the  decomposition  is  performed  in  glass 
vessels,  the  fluorine,  as  it  is  separated,  acts  upon  the  silica  contained  in 
the  glass,  so  that  fluoride  of  silicium  is  formed  and  oxygen  set  free.  If 
platinum  vessels  are  employed,  the  metal  becomes  covered  with  a  red- 
brown  powder  (fluoride  of  platinum  ?) ;  if  the  platinum  vessel  is  coated 
internally  with  fused  chloride  of  potassium,  the  decomposition  of  the 
fluoride  is  attended  with  the  production  of  a  gas  which  attacks  glass,  and 
has  a  peculiar  odour,  more  disagreeable  than  that  of  chlorine.  (H.  Davy.) 

Aim6  {Ann.  Ghim.  Phyi.  b&,  443;  also  Pogg.  32,  676;  also  J.  jyr, 
Chem.  2,  469),  passed  chlorine  gas,  in  the  cold,  over  fluoride  of  silver 
contained  in  glass  vessels  which  were  covered  with  a  coating  of  caout- 
chouc.    Hydrofluoric  acid  was  produced  and  the  caoutchouc  carbonized. 

Baudrimont  {J.  Chim.  Med.  12,  374 ;  also  J.  pr.  Chem.  7,  447),  passed 
ffaseous  fluoride  of  boron  over  ignited  red  lead,  and  conducted  the  gaseous 
fluorine  which  was  evolved  into  a  dry  glass  vessel.  He  also  heated  fluor- 
spar in  a  glass  vessel  with  manganese  and  oil  of  vitriol ;  whereupon  fluo- 
rine gas  was  evolved  mixed  with  gaseous  fluoride  of  silicium  and  vapour 
of  hydrofluoric  acid.  In  both  cases  he  obtained  a  yellowish  brown  gas, 
which  smelt  like  chlorine  and  also  like  burnt  sugar,  decolorized  solution 
of  indigo,  did  not  attack  glass,  but  combined  with  gold  and  platinum. 

G.  J.  Knox  and  Th.  Knox  {Phil.  Mag.  J.  9,  107;  also  J.  pr.  Chem. 
9,  118),  heated  fluoride  of  mercurv  in  a  vessel  of  fluor-spar,  till  a  glass 
plate  laid  on  the  top  no  longer  became  covered  with  drops  of  water; 
then  passed  dry  chlorine  gas  into  the  vessel  through  a  bent  glass  tube 
drawn  out  to  a  point  at  the  end;  closed  the  vessel  tightly,  when  full  of 
chlorine,  with  a  plate  of  fluor-spar;  and  applied  heat  to  the  bottom. 
Protochloride  of  meronry  sublimed^  and  the  vessel  was  filled  with  a  yel- 


3  GO  FLUORINE. 

lowish  green  gas,  ^hich  did  not  fume  in  contact  with  air,  and  therefore 
did  not  contain  hydrofluoric  acid,  but  rapidly  corroded  a  glass  plate  laid 
on  the  top  of  the  vessel.  Fluoride  of  leatd  was  found  not  to  be  decom- 
posed by  chlorine,  even  with  the  aid  of  heat 

G.  J.  Knox  (Phil.  Mag.  J.  16,  192,  also  J.  pr.  Chem.  20,  172),  fiUed 
a  vessel  of  fluor-spar  half  full  of  anhydrous  hydrofluoric  acid,  and  closed 
it  with  a  cover  of  fluor-spar  having  three  holes  in  it.  Through  the 
middle  aperture,  a  platinum  wire  forming  the  negative  electrode  of  a 
sixty-pair  battery,  was  passed  into  the  acid;  through  one  of  the  biteial 
apertures,  a  piece  of  charcoal^  freed  from  iron  and  silica  by  boiling  in 
nitric  and  in  hydrofluoric  acid  (as  otherwise,  fluoride  of  iron  ajid  fluoride 
of  silicium  would  have  been  formed),  was  introduced  to  form  the  positive 
electrode.  The  other  lateral  aperture  served  to  introduce  various  sub- 
stances, for  the  purpose  of  observing  the  effect  produced  upon  them  by 
the  fluorine  gas  which  might  be  evolved.  A  large  quantity  of  hydrogen 
gas  was  evolved  on  the  platinum  wire;  litmus  paper  introduced  through 
the  side  opening  was  bleached  in  two  hours  (hydrofluoric  acid  does  not 
bleach  litmus) ;  gold  was  attacked  and  turned  brown,  after  the  battery  had 
been  acting  for  fifteen  hours.  The  gas,  when  passed,  as  it  was  evolved, 
through  a  tube  of  transparent  fluor-spar,  was  found  to  be  colourless. 
Also,  when  melted  fluoride  of  lead  contained  in  a  bent  glass  tube  {App.  5), 
was  decomposed  by  means  of  a  cathode  of  platinum  and  an  anode  of 
charcoal,  a  considerable  number  of  gas-bubbles  were  evolved  at  the 
anode ;  the  gas  immediately  acted  on  the  glass,  and  consequently  did  not 
bleach  litmus  paper. 

IT.  Louyet  {Compt,  Rend.  22,  960),  decomposed  fluoride  of  silver,  in 
Knox's  appaQitus,  by  means  of  chlorine  or  iodine,  and  obtained  a  gas 
which  was  colourless  in  thin  strata;  did  not  bleach  vegetable  colours ; 
decomposed  water  rapidly;  acted  but  slowly  upon  glass,  but  attacked 
most  metals ;  gold  and  platinum,  however,  were  not  attacked  by  it.  %. 

Fluorine  mast,  at  all  events,  be  a  permanent  gas^  since  it  forms 
gaseous  compounds  with  boron  and  silicium.  (I,  86.) 

Atomic  weight  of  fluorine  =  19  (H  =  1),  or  237'50  (0  =  1.)  Louyet, 
{Ann,  Chim.  Phys,  2b,  291.) 


Compounds  ofFltiorine. 

Fluorine  and  Hydrogen. 

Hydrofluoric  Acid. 

Fluoric  acid,  FluuspathBdure,  Spathsdure,  Fluorwasserstoffsdure,  Acide 
Jtuoriqtie,  Acide  hydrofiuorique,  Acide flitorkydrique. 

Preparation,  One  part  of  pounded  fluor-spar,  free  from  silica,  is 
heated  in  a  leaden  or  platinum  retort  (the  former  must  not  be  soldered 
with  tin),  with  2  parts  of  oil  of  vitriol,  a  receiver  of  lead  or  platinum 
being  adapted  without  luting  to  the  retort,  and  surrounded  with  ice. 
(Gay-Lussac  &  Thenard.) 

CaP  +  HO,SO=»  =  CaCSC  +  HP. 
If  the  fluor-spar  contains  silica,  fluosilicic  acid  gas  passes  over,  being 
evolved  in  gas-bubbles,  even  before  the  mixture  is  heated ;  if  it  contains 
galena,  hydrosulphuric  acid  and  sulphurous  acid  pass  over,  and  the 
distillate  is  clouded  with  sulphur,  (oerzelius.)  The  product  must  be 
preserved  in  close  vessels  of  gold,  platinum,  or  lead  free  from  tin. 


HYDROFLUORIC   ACID.  361 

Properties.  Transparent  and  colourless  liquid,  of  specific  gravity 
1-0609.  (H.  Dayy.)  Does  not  solidify  at  -  20°.  (Gay-Lussac  &  The- 
nard.)  Refracts  light  verjr  feebly.  (WoUaston.)  Boils  at  comparatively 
low  temperatures — according  to  Berzelius,  not  much  above  IS"". — Has  a 
pungent  odour,  and  acts  very  iniuriously  on  the  respiratory  organs ;  even 
the  vapour  produces  pains  under  the  nails.  Small  drops  placed  upon 
the  skin  produce  white  spots,  which  rise  up  into  pustules  and  are 
attended  with  violent  pain,  often  exciting  vulnerary  fever.  The  applica- 
tion of  caustic  potash  solution,  followed  by  emollient  poultices,  is  useful 
in  these  cases ;  the  pustules  should  also  be  opened.  The  acid  reddens 
litmus  strongly.  (Gay-Lussac  &  Thenard.) 


F  

H 

..  18-7  .... 
..     1       .... 

....  94-92  .... 
....     5-08  .... 

....  94-95 
....     5-05 

HP.... 

...  197  .... 

....  1000  .... 

....  100-0 

IT.  According  to  Louyet,  the  acid  obtained  by  the  action  of  oil  of 
vitriol  on  fluor-spar  is  a  hydrate ;  and  the  true  anhydrous  acid  can  only 
be  obtained  by  distilling  this  hydrate  with  anhydrous  phosphoric  acid.  A 
gaseous  product  is  then  obtained  which  is  auite  free  from  water,  and  does 
not  liquefy  at  —  12**  (  -h  10*4®  F.)  under  the  ordinary  atmospheric 
pressure.  It  fumes  very  strongly  in  the  air,  but  has  scarcely  any  action 
upon  glass.  Louyet  is  of  opinion  that  it  might  be  collected  over  mer- 
cury in  perfectly  dry  glass  vessels.  IT. 

Decompositions. — 1 .  In  the  circuit  of  the  voltaic  battery,  hydrofluoric 
acid  yields  hydrogen  gas  at  the  negative  pole,  while  the  positive  platinum 
wire  becomes  corrodea  with  a  brown  mass  (of  fluoride  of  platinum  ?)  JET. 
Davy. — 2.  Potassium,  sodium,  unignited  silicium,  tantalum,  zinc,  iron,  and 
manganese,  brought  in  contact  with  this  acid,  produce  metallic  fluorides 
and  hydrogen  gas  :  in  the  case  of  potassium,  the  action  is  attended  with 
explosion  and  vivid  combustion.  (Gay-Lussac  &  Thenard ;  Berzelius.) — 
3.  With  lime,  the  acid  forms  fluoride  of  calcium  and  water,  great  rise  of 
temperature  attending  the  action.  In  contact  with  silica  (e.  g.  with 
glass),  it  becomes  hot,  boils  up,  and  is  converted  into  gaseous  fluoride  of 
silicium,  nothing  but  a  small  quantity  of  aqueous  hydrofluosilicic  acid 
remaining.  (Gay-Lussac  &  Thenard.)  With  most  other  metallic  oxides, 
also,  it  forms  water  and  a  fluoride  of  the  metal,  (or  a  hydrofluate  of  the 
oxide.) — Not  decomposed  by  chlorine,  oil  of  vitriol,  or  hydrochloric  acid, 

ComJbinaiiviM.  a,  AgueotLs  Hydrofluoric  Acid.  The  affinity  between 
water  and  hydrofluoric  acid  is  very  strong;  hence  the  acid  fumes  in  the 
air.  The  act  of  combination  is  attended  with  a  development  of  heat 
which  raises  the  liquid  to  the  boiling  point.  With  a  certain  proportion 
of  water,  the  specific  gravity  of  the  liquid  acid  is  as  hi^h  as  1*250.  (H. 
Davy.)  According  to  Berzelius,  the  hydrated  acid  is  best  prepared  by 
gradually  and  gently  heating  a  mixture  of  fluor-spar  and  oil  of  vitriol,  in 
a  leaden  bottle  to  the  mouth  of  which  a  bent  leaden  tube  is  adapted 
by  means  of  a  stopper  also  of  lead,  the  joints  being  made  air-tight 
with  oil  of  vitriol  or  melted  caoutchouc ;  the  other  end  of  the  bent  tube 
dips  just  below  the  surface  of  water  contained  in  a  leaden  bottle  or  pla- 
tinum crucible  surrounded  with  ice.  The  acid  obtained  by  this  process 
may  be  freed  from  silica,  which  is  almost  always  present  in  fluor-spar. 


aes  FLuoRim. 

hj  dropping  into  it  h  solution  o  flnotida  of  potasrinita,  as  long  as  a 
gelatinous  precipitate  of  fluoride  of  silicium  and  potassium  is  produced, 
for  by  adding  pounded  fluoride  of  hydrogen  and  potassium,  as  long  sa  it 
dissofyes) — then  pouring  ofi*  the  clear  liquid  and  distilling  in  platinum 
vessels.  The  acid  maj  be  preserved  in  bottles  of  gold,  platinum,  or  lead, 
having  a  leathern  collar  soaked  in  wax  laid  upon  the  neck,  and  then  a  cap 
screwed  on.  A  dilute  solution,  not  required  to  be  quite  free  from  silica;, 
maj  also  be  kept  in  glass  vessels  coated  inside  with  wax. 

Transparent,  colourless,  thin  liquid,  which  fumes  in  the  air  when 
concentrated;  when  heated,  it  gives  off  hydrofluoric  acid,  and  is  thereby 
rendered  weaker. 

b.  With  Peroxide  of  Hydrogen.     (II.  78.) 

e.  With  Salifiable  Bases,  forming  salts  called  Bydrofiuaie$,  (Vid. 
Metallic  Fluorides.) 

Fluorine  and  Boron. 
A.  Fluoride  of  Boron.  BF'. 

Fluohorio  gas,  Fltiorharongas,Jltissboraxsaures  Gas,  GasJluorhariqHe, 

Preparation. — 1.  One  part  of  vitrefied  boracic  acid  and  2  parts  of  fluor- 

rfree  from  silica  are  heated  to  whiteness  in  a  wrought  iron  gun-barrel 
od  in  an  inclined  position  (Gay-Lussac  &  Th^nardJ  {Sck.  107). 
3C»F  +  7B0»  =  3{CaO,2BO'')  +  BF». 

— 2.  One  part  of  vitrefied  boracic  acid,  2  of  fluor-spar,  and  12  of  oil  of 
vitriol,  are  gently  heated  in  a  glass  vessel.  (J.  Davy).  Ferrari  {J.  Fharm. 
19,  48)  uses  1  part  of  vitrefied  boracic  acid,  1  of  fluor-spar,  and  20  of  oil  of 
vitriol.  The  residue  in  the  second  process  consists  of  sulphate  instead  of 
borate  of  lime.  According  to  Berzelius,  the  gas  prepared  by  method  2, 
contains  a  large  quantity  of  fluoride  of  silicium  (proceeding  from  the 
silica  mixed  with  the  flaor  spar,  and  from  the  glass  vessel),  which  can 
only  be  imperfectly  separated  by  contact  with  crystallized  boracic  acid. 
The  gas  is  collected  over  mercury. 

Properties.  Colourless  gas.  Specific  gravity  (I.  280).  Incombustible, 
does  not  support  combustion ;  has  a  pungent  odour  like  that  of  fluoride 
of  silicium;  very  suffocating.  Reddens  litmus  paper  strongly.  Chars 
organic  substances  rapidly.  In  contact  with  moist  air  it  forms  a  very 
thick,  white  cloud.  When  subjected  to  the  action  of  the  carbonic  acid 
bath  in  vacuo,  it  condenses  to  a  clear,  colourless  liquid,  which,  even  at 
that  temperature,  is  as  mobile  as  warm  ether.  (Faraday.) 

Calculation. 

B  10-8  16-14  16-24 

3F  661  83-86  83*76 

BF»    ....  66-9  100-00  10000 

Vol.  Sp.gT.  Vol.  Sp.gr. 

Vapour  of  Boron? 1  0-7487      =        * 0*3744 

Pluorlnega«.> 3  3-8892      =      H 1*9446 

Fluoboiicgas 2  4-6379      =      1  2-3190 

(BP  =  136-20  +  6  .  116-90  =  837-60.    BeracUus.) 


FLUOBOBIC  ACID.  ^  S6|i 

DeeomposiUwns. — 1.  By  water  into  hjdroflaoric  and  boracic  acid, 
3  At.  hydrogen  from  the  water  combining  with  3  atoms  of  flaorine,  and 
8  atoms  of  oxygen  with  1  atom  of  boron. — 2.  Potassium  heated  in  fluo- 
borio  gas  bums  (as  soon  as  the  black  crust  which  first  forms  has  burst) 
with  a  bright,  reddish  flame  j  absorbs  a  quantity  of  the  gas,  the  volume 
of  which  is  three  times  as  great  as  that  of  the  hydrogen  which  the 
potassium  would  liberate  from  water;  and  is  converted  into  a  brown 
fusible  mass,  which  appears  to  be  a  mixture  of  boron  and  fluoride  of 
potassium,  and  is  separated  by  water — with  evolution  of  a  small  quantity 
of  hydrogen  gas — ^into  fluoride  of  potassium  or  hydrofluate  of  potassa 
which  dissolves,  and  boron  which  remains  behind.  Sodium  behaves  in 
the  same  manner,  excepting  that  the  combustion  is  more  vivid  and  a 
larger  quantity  of  gas  is  absorbed.  ^ay-Lussac  &  Thenard.)  Red-ho{ 
iron  has  no  action  on  this  gas. — 3.  jBurnt  lime  absorbs  fluoborio  acid 
quickly,  especially  when  heated;  the  resulting  mass  is  fusible,  and  when 
treated  with  oil  of  vitriol,  evolves  fluoborio  gas.  (J.  Davy,  N.  Ed,  FhU.  J. 
17,  246.)  [In  this  case,  a  mixture  of  fluoride  of  calcium,  and  borate  of 
lime  is  probably  formed.     4CaO  +  BP»  =  3CaF  +  CaO,  B0».] 

CoTnhinations.  a.  With  ammonia,  h.  With  metallic  flnorides,  form- 
ing compounds  called  Metallic  Fliiohorides,     (Vid.  MetcUlio  Fluorides,) 

B.    Htdrofluates  op  Boraoio  Aoid. 

a.    Fluoborio  Acid.     BO*,  3HF. 

Formation.  By  saturating  water  with  fluoborio  acid  gas.  Water,  at 
ordinary  temperatures  absorbs  about  700^  measures  of  fluoboric  gas  (J. 
Davy);  according  to  Gay-Lussao  &  Thenard,  about  the  same  volume 
as  of  hydrochloric  acid  gas.  The  absorption  is  rapid,  and  attended  with 
great  nse  of  temperature  (BF»  +  3H0  =  B0»  +  3HF). 

Freparaiion, — 1.  The  fluoborio  gas  as  it  is  evolved,  is  passed  through  a 
bent  tube  dipping  under  mercury  which  is  covered  with  a  small  quantity 
of  water.  (Thenard.)  If  the  end  of  the  tube  were  to  dip  into  the  water, 
the  rapid  absorption  of  the  gas  would  cause  the  liquid  to  pass  back  into 
the  generating  vessel. — 2.  Boracic  acid  is  dissolved  in  aqueous  hydro- 
fluoric acid,  and  the  solution  concentrated  by  evaporation  till  the  com-f 
pound  begins  to  evaporate  unchanged.  (Berzefius.) 

Properties,  The  solution  formed  by  the  absorption  of  700  measures  of 
the  gas  has  a  specific  gravity  of  1  '770;  it  is  colourless,  fuming,  and  oily, 
very  corrosive,  and  chars  organic  substances.  The  liquid  saturated  with 
fluoboric  gas,  gives  off  when  boiled,  only  one-flfth  of  the  gas  undecom- 
posed:  after  that,  its  boiling  point  rises  &r  above  100°,  and  it  may  then 
DO  distilled  without  decomposition. 

Decomposition.  By  dilution  with  water,  into  hydrofluoboric  acid  and 
boracic  acid,  the  latter  separating  in  the  solid  form. 

ComHnations. — a.  With  sulphuric  acid.— 'j?.  With  hydroflnates  qf 
metallic  oxides.     (Yid.  Metallic  Fluorides,) 


364  FLUORINE. 

h.  Hydropluobobic  Acid.    B0',4HF. 

1.  Wben  fluoboric  gas  or  aqneoas  eolation  of  fluoboric  acid  comes 
in  contact  with  a  considerable  quantity  of  water,  one-fourth  of  the  boracic 
acid  is  set  at  liberty,  and  separates,  sometimes  in  gelatinous  flakes,  some- 
times as  a  crystalline  powder,  while  hjdrofluoboric  acid  remains  in  the 
liquid. 

4  (BO',  3HF)  =  3(B0»,  4HF)  +  B0»; 
or,  if  it  be  supposed  that  1  atom  of  boracic  acid  is  replaced  in  the  liqnid 
by  3  atoms  of  water : 

4(BO',3HF)  +  3HO=^3(BO>,3HF  +  HO,  HF)  +  BO»; 
according  to  the  latter  view,  hydrofluoboric  acid  ha  a  compound  of  fluobo- 
ric acid,  with  a  hydrate  of  hydrofluoric  acid,  =  B0',3HF  +  HO,  HF ;  and 
corresponds  to  those  salts  of  fluoboric  acid  in  which  an  atom  of  water  is 
replaced  by  an  atom  of  a  metallic  oxide. — 2.  The  same  liquid  is  obtained 
by  dissolving  crystallized  boracic  acid  in  dilute  hydrofluoric  acid,  adding 
the  boracic  acid  in  small  quantities  at  a  time,  till  the  liquid  is  saturated, 
and  decanting  the  solution  from  the  excess  of  boracic  acid.  (Beraelius.) 

If  the  liquid  is  left  to  evaporate  spontaneously,  hydrofluoric  acid 
escapes  and  fluoboric  acid  remains;  if  it  be  left  to  evaporate  in  contact 
with  boracic  acid,  the  hydrofluoric  acid  t^ikes  np  more  boracic  acid,  as  the 
Quantity  of  water  diminishes,  and  at  length  the  whole  is  converted  into 
fluoboric  acid.  (Berzelius.) 

H  Berzelius  supposes  that  when  fluoboric  gas  is  passed  through  water, 
in  quantity  sufficient  to  render  it  strongly  acid,  but  not  to  saturate  it,  an 
interchange  of  elements  takes  place  between  the  water  and  a  portion  of 
the  fluoride  of  boron,  whereby  hydrofluoric  acid  and  boracic  acid  are 
formed,  and  the  hydrofluoric  acid  combines  with  the  undecomposed  fluo- 
ride of  boron  :  thus, 

4BF»  +  3H0  =  B0»  +  3(BF^  HF). 

The  compound  BF',HF  is  not  known  in  the  separate  state,  but  is  obtained 
in  the  form  of  aqueous  solution,  by  either  of  the  processes  above  men- 
tioned (BO',  4HF  =  BF',  HF  -h  3H0).  When  it  comes  in  contact  with 
a  salifiable  base,  its  hydrogen  is  oxidated  at  the  expense  of  that  base,  and 
the  radical  of  the  base  combines  with  the  fluorine:  the  result  is  a  com- 
pound of  a  metallic  fluoride  with  fluoride  of  boron :  thus,  with  potasaa : 
BF»,HF  -h  KO  =  BF»,KF  ^  HO.  (Berzelius,  TraUS,  I.,  765.)  T 

Fluorine  and  Phosphorus. 

Fluoride  op  Phosphorus. — First  obtained  by  Sir  H.  Davy,  by  dis- 
tilling phosphorus  with  fluoride  of  lead  or  fluoride  of  mercury,  a  phosphide 
of  the  metal  being  left  behind.  Prepared  by  distilling  fluoride  of  lead 
with  phosphorus.  Colourless,  strongly  fuming  liqnid,  corresponding  to 
terchloride  of  phosphorus.  (Dumas,  Ann.  Chim.  Fkps.  31,  435.) 

Fluorine  and  Sulphur. 

A.  Fluoride  op  Sulphur. — By  distilling  fluoride  of  lead  or  fluoride 
of  mercury  with  sulphur.  (H.  Davy,  Dumas.) 

B.  Sulphate  op  Fluoride  op  Boron. — Oil  of  vitriol  of  specific 
gravity  1-850  absorbs  50  times  its  volume  of  fluoboric  gas.      The  same 


METALLIC  FLUORIDES.  3f5S 

compound  is  also  obtained  as  a  distillate  towards  the  end  of  tbe  operation 
for  preparing  flaoride  of  boron.  Very  viscid,  faming  mixture,  more  vola- 
tile than  pure  oil  of  vitriol.  When  it  is  mixed  with  water,  a  very  dense, 
white  precipitate  is  formed.  (J.  Davy.) 


Fluorine  and  Selenium. 

Fluoride  of  Selenium. — Vapour  of  selenium  passed  over  fluoride  of 
lead  kept  in  a  state  of  fusion  iu  a  platinum  crucible,  produces  fluoride  of 
selenium,  which  condenses  in  crystals  in  the  receiver.  These  crystals  may 
be  volatilized  without  decomposition  at  a  high  temperature ;  thev  dissolve 
in  concentrated  hydrofluoric  acid,  but  are  instantly  decomposed  by  contact 
with  water.  (G.  J.  Knox.) 

Other  Compounds  op  Fluorine. 

With  the  metals,  fluorine  forms  the  Metallic  Fluorides  or  Hypotheti' 
tally  anhydrous  Fluates  {Fluorures,  FluaUs  sees).     These  compounds  are 
formed — 1.  When  hydrofluoric  acid  is  brought  in  contact  with  various 
metallic  oxides,  hydrogen  gas  being  also  disengaged. — 2.  By  bringing 
hydrofluoric  acid  in  contact  with  metallic  oxides — ^^rhereby,  either  a  solid 
metallic  fluoride  is  formed  directly,  or  a  hydrated  metallic  fluoride  or 
hydroflnate  is  produced,  and  subsequently  decomposed  by  heat  into  water 
and  a  solid  metallic  fluoride. — 3.  By  heating  electro-negative  metals  with 
fluoride  of  lead  or  fluoride  of  mercury. — 4.  When  the  metallic  fluoride  to 
be  formed  is  volatile,  it  may  be  formed  by  heating  fluor-spar  with  the 
metallic  oxide  and  oil  of  vitriol.     The  metallic  oxide  gives  up  its  oxygen 
to  the  calcium,  which  remains  in  the  form  of  sulphate  of  lime,  and  the 
fluorine  combines  with  the  metal,  forming  a  metallic  fluoride  which  distils 
over.     The  fluorides  have  no  metallic  lustre ;  one  of  them,  the  fluoride  of 
silicinm,  is  gaseous ;  most  of  them  are  easibly  fusible,  and  for  the  roost  part 
resemble  the  metallic  chlorides.     They  are  not  decomposed  by  ignition, 
either  alone  or  mixed  with  charcoal.    When  ignited  in  the  air,  in  a  flame 
which  contains  aqueous  vapour,  many  of  them,  as  fluoride  of  calcium  and 
cryolite,  take  up  oxygen  and  are  converted  into  metallic  oxides,  while 
the  fluorine  is  given  off  in  the  form  of  hydrofluoric  acid.  (Smithson,  Ann. 
Phil.  23,  100.)     Chlorine  decomposes  the  fluorides  of  potassium,  sodium, 
mercury,  and  silver,   converting  them  into  chlorides,  (Sir  H.  Davy.) 
Metallic  fluorides  are  not  decomposed  by  ignition  with  glacial  phosphoric 
acid,  unless  silica  is  also  present  (the  latter  then  gives  up  its  oxygen  to 
the  metal,  while  the  silicmm  escapes  in  combination  with  the  fluorine) 
(Gray-Lussao  &  Th^uard.)     Vapour  of  anhvdrous  sulphuric  acid  passed 
over  fluoride  of  calcium  or  any  other  metallic  fluoride  ignited  in  a  plati- 
num tube,  does  not  effect  the  slightest  decomposition. '  Hydrochloric  acid 
gas,  under  these  circumstances,  liberates  hydrofluoric  acid.  (Kuhlmann, 
Pogg.    10,  618.)     Aaueous  sulphuric  and  nitric  acid  decompose  most 
metallic  fluorides,  yielding  a  sulphate  or  a  nitrate  and  hydrofluoric  acid. 
Oil  of  vitriol  dissolves  many  metallic  fluorides  at  ordinary  temperatures, 
forming  a  thick,  tenacious  liquid  which  evolves  hydrofluoric  acid  when 
heated.     When  a  metallic  fluoride  is  gently  heated  with  oil  of  vitriol 
in  a  platinum  crucible — ^the  crucible  covered  with   a   glass  plate   ou 
which  a  difficultly  fusible  etching  ground  has  been  laid — lines  tra<;cd 
out  upon  it— the  plate  removed  after  a  while-*and  tbe  etching  ground 


866  FLUORINB. 

oleaned  off, — ^the  lines  are  fonnd  to  be  bitten  in,  and  appear  particnlarly 
distinct  when  breatbed  npon.  If  tbe  aqueons  solution  of  a  metallio 
fluoride  be  mixed  with  sulphuric  acid,  and  the  mixture  left  to  dry  on 
a  glass  plate  similarly  waxed  and  etched,  the  lines  on  the  plate  are 
likewise  rendered  opaque.  If  the  metallic  fluoride  is  very  small  in 
quantity  or  contaminated  with  silica,  the  mixture  with  sulphuric  acid 
should  be  left  to  evaporate  on  a  watch-glass — which  would  not  be  attacked 
by  sulphuric  acid  sdone — and  the  residue  washed  off  with  water;  the 
spot  on  which  the  mixture  has  evaporated  appears  dull,  (fierzelius.) 

Hydrated  MetcUlic  Fluorides,  Scdts  of  Hydrofiuorie  acid,  or  ffydrojlu- 
ates  {Hydrojluor-Salze,  fiuorwasseritofftdure  Salte,  Hydrojlnatea,  PUtorhy^ 
<ira/e«).~— These  compounds  are  obtained; — 1.  By  dissolving  metallic  fluo- 
rides in  water.  Some  metallic  fluorides  dissolve  readily  in  water  (the 
fluorides  of  tin  and  silver);  others  sparingly  (potassium,  sodium,  and 
iron) ;  many  are  but  very  slightly  soluble  (the  fluorides  of  strontium  and 
cadmium) ;  and  many  not  at  all  (barium,  calcium,  magnesium,  cerium, 
and  yttrium). — 2.  By  dissolving  a  metallic  oxide  in  aqueous  hydrofluoric 
acid  (oxide  of  titanium,  oxide  of  tantalum,  and  tungstic  acid). — 3.  By 
dissolving  various  metals  in  aqueous  hydrofluoric  acid,  the  solution  beinff 
attended  with  evolution  of  hydrogen  gas  (zirconium,  tantalum,  unignited 
silicium) ;  or  in  a  mixture  of  hydrofluoric  acid  and  nitric  acid  (titanium, 
tantalum,  ignited  silicium).  The  solutions  of  the  simple  hydrofluates  of 
ammonia,  potash,  and  soda,  have  an  alkaline  reaction.  The  evaporation 
and  cooling  of  the  solution  of  a  metallic  fluoride  yields  hydra  ted  crystals 
in  some  few  cases;  but  more  generally,  an  anhydrous  fluoride.  Solutions  of 
metallic  fluorides  attack  glass  vessels  in  which  they  are  evaporated  or  merely 
preserved.  The  aqueous  solutions  mixed  with  lime-salts  give  a  precipi- 
tate of  fluoride  of  calcium  in  the  form  of  a  transparent  g^atinous  mass, 
which  is  scarcely  visible,  because  its  refractive  power  is  nearly  the  same  as 
that  of  the  liquid :  the  addition  of  ammonia  makes  it  plainer.  This  pre- 
cipitate, if  it  does  not  contain  silica,  dissolves  with  difficulty  in  hydro- 
chloric or  nitric  acid,  and  is  again  precipitated  by  ammonia.  From  ace- 
tate of  lead,  the  aqueous  metallio  fluorides  generally  precipitate  fluoride 
of  lead  in  a  pulverulent  form.  They  do  not  precipitate  nitrate  of 
silver. 

Hydrofiuaies  of  Metallic  Fluorides,  Add  Metallic  Fluorides  of  Ber- 
telius.—lAvjij  metallic  fluorides  combine  with  one  atom  of  hydrofluoric 
acid,  forming  compounds  which  are  frequently  crystalline.  These  com- 
pounds dissolve  in  water,  forming  solutions  which  redden  litmus  and  may 
be  regarded  as  solutions  of  bi-hydrofluates  of  metallic  oxides. 

KF,  HF  +  HO  =  KO,  2HF. 

Many  metallic  fluopdes  which  are  insoluble  in  water,  such  as  the  fluorides 
of  barium  and  calcium,  dissolve  in  aqueous  hydrofluoric  acid ;  and  many 
which  are  sparingly  soluble  in  water  dissolve  with  greater  facility  in 
aqueous  hydrofluoric  acid.  (Berzelius.) 

Metallic  Fluohorides.  Many  metallic  fluorides  combine  with  one 
atom  of  fluoride  of  boron.  Thus,  the  double  fluoride  of  boron  and  po- 
tassium is  KF,  BF'.  These  compounds  are  obtained  in  solution : — 1.  By 
mixing  an  aqueous  solution  of  fluoboric  acid  with  a  metallic  fluoride.'^— 
2.  By  dissolving  a  metallic  oxide  in  hydroflnoborio  acid. 

KO  +  B0»,  4HP  =  KP  +  BP»  +  4H0; 


METALLIC  RiUORIDES.  86{^ 

or,  if  we  suppose  that  tlie  solation  contains  a  hjdroflnate  of  tbe  metalUe 
oxide  combined  with  hydroflnoboric  acid,  the  mode  of  formation  will  be : 

KO  +  BO>,4HP  =  KO.HF  +  BO»,3HP. 
— 3.  Bj  mixing  the  aqneons  solution  of  the  hydrofluate  of  a  metallic  oxide 
with  boracic  acid;  under  these  circumstances,  howerer,  half  the  metal  is 
set  free  in  the  form  of  oxide. 

2(KF,HF)  +B0»  =  KF,BF»  +  KO  +  2H0; 
or,  on  the  assumption  that  the  solution  contains  fluoborate  of  potassa : 
2(KO,2HF)  +  BO»  =  (KO,HF  +  B0»,3HF)  +  KO. 

This  liberation  of  the  metallic  oxide  explains  the  phenomenon  first  ob- 
served by  Zeise,  {Schw»  82,  306,)  viz.  that  the  solution  of  bihydrofluate  of 
ammonia,  potassa,  or  soda,  which  has  an  acid  reaction,  becomes  alkaline 
on  the  addition  of  boracic  acid.  When  the  solutions  obtained  by  either 
of  these  methods  are  evaporated  to  the  crystallizing  point  or  to  dryness, 
the  anhydrous  metallic  nuoborides  remain  behind. 

These  compounds,  when  heated  to  redness,  evolye  fluoboric  gas  and 
are  converted  into  metallic  fluorides.  When  distilled  with  oil  of  vitriol, 
they  yield  gaseous  fluoride  of  boron,  together  with  liquid  fluoboric  acid, 
and  excess  of  hydrofluoric  acid,  (which  corrodes  glass,)  and  leave  a  sul- 
phate of  the  metallic  oxide.  (Berzelius.)  Most  of  the  metallic  fluoborides 
dissolve  in  water  either  without  alteration  as  fluoborides,  or  as  flnoborates 
of  metallic  oxides — that  is  to  say,  as  double  salts,  composed  of  1  At.  of 
mono-hydrofluate  of  a  metallic  oxide  and  1  At.  of  terhydrofluate  of  boracic 
acid,  (fluoboric  acid,)  the  boracic  acid,  in  &ct,  playing  the  part  of  one 
of  the  bases  of  the  double  salt.  The  solutions  yield  by  evaporation  either 
crystals  of  anhydrous  metallic  fluoboride  or  of  the  hydrated  compound. 
(Berzelius.) 

Fluoride  of  phosphorus  and  fluoride  of  sulphur  likewise  enter  into 
combination  with  metallic  fluorides,  as  with  fluoride  of  sodium,  <fec. 
(Berzelius.) 

Compeunds  of  metallic  Fluorides,  one  with  the  the  other,  MetaUxc 
Fliu>rine  salts.  The  compounds  of  electro -negative  metals  with  fluorine, 
such  as  bifluoride  of  silicium,  bifluoride  of  platinum,  sesquifluoride  of 
-aluminum,  chromium,  uranium  or  iron,  &c.,  combine  with  the  electro- 
positive metallic  fluorides  (as  the  fluorides  of  potassium,  sodium,  &c.) 
generally  in  equal  numbers  of  atoms.  The  metallic  fluorine-salts  are 
sometimes  obtamed  by  directly  mixing  the  two  metallic  fluorides  dissolved 
in  water,  sometimes  by  bringing  an  electro-positive  compound  of  hydro- 
fluoric acid  and  a  metallic  fluoride  (an  alkaline  bihydrofluate  for 
example,)  in  contact  with  an  electro-negative  metallic  oxide.  Most  me- 
tallic fluorine-salts  dissolve  in  water  less  easily  than  the  metallic  fluorides 
which  they  contain.  (Berzelius.)  The  aqueous  solution  may  be  supposed 
to  contain  a  double  hydrofluate : 

NaF,SiF*  +  3H0  =  NaO,HF  +  SiO*^2HF. 

The  reactions  of  hydrofluoric  acid  may  also  be  explained  npon  the 
older  theory— corresponding  to  that  already  given  with  regard  to  hydro- 
chloric acid — according  to  which,  the  acid  obtained  from  fluor-spar  is 
regarded  as  a  compound  of  water  with  an  acid  not  yet  obtained  in  the 
free  state,  and  this  again  as  a  compound  of  oxygen  with  an  unknown 
radical,  Fltioritim  or  Fluoricum,  The  atomic  weight  of  fluorium  may 
either  be  estimated  at  2*7;  in  which  case,  1  At.  fluorium  with  1  At. 
oxygen  will  form  1  At.  (=10-7)  hypothetically  anhydrous  fluoric  acid 


368  NITROGEN. 

this  ID  combinatioD  with  1  At.  water,  will  form  1  At.  (=19'6)  hjdroflaorie 
acid  in  the  state  described  on  p.  360;  and  the  hypothetical  substance,  fluo- 
rine, which  the  chlorine  theory  supposes  to  exist,  must  be  regarded  as  a 
compound  of  one  atom  of  fluorium  with  two  atoms  of  oxygen  (=18*7). 
Or :  we  may,  according  to  Berzelius*s  earlier  theory,  double  the  atomic 
weight  of  fluorium  (=5'4);  in  which  case  it  will  require  2  atoms  of  oxy- 
gen to  form  1  atom  of  the  h3rpothetically  anhydrous  fluoric  acid,  which 
in  combination  with  2  atoms  of  water,  produces  1  atom  (=39  4)  of  hydro- 
fluoric acid  (p.  360).  Gaseous  fluoride  of  boron  is  a  compound  of  hypo- 
thetically  anhydrous  fluoric  acid  with  boracic  acid;  and  the  metallic 
fluorides,  namely  gaseous  fluoride  of  silicium,  fluor-spar,  &c.,  are  com- 
pounds of  hypothetically  anhydrous  fluoric  acid  with  metallic  oxides. 
The  reason  why  the  anhydrous  hydrofluates  are  not  decomposed  by  anhy- 
drous acids, — with  the  exception  of  boracic  acid,  which  is  capable  of 
acting  as  a  base  to  anhydrous  fluoric  acid, — as  well  as  all  other  explana- 
tions connected  with  the  subject,  correspond  exactly  with  those  already 
giyen  under  Chlorine. 


Chapter  XII. 

NITROGEN. 


Compounds  of  Nitrogen  and  Oxygen, 

Lavoisier.     Crell,  Neueste  Endeck,  2,  1 25. 

Cavendish.     CreU.  Ann,  1786,  1,  99. 

Demian,  Troostwyk,  Lauwerenburg  k  Vrolik,  NUrotLS  Acid,  Schw.  J.  7 , 

243, 
Sir  H.  Davy.     Chemical  and  Philosophical  Researches  chiejly  concerning 

Nitrous  Oxid^,     London  1800. 
Berzelius.     Gilb.  40,  162.     GUb,  46,  131. 
Gay-Lussac.     Ann,  Chim.  Phys,  1,  394;  also  GUh,  58,  29;  also  Schw. 

17,  236. 
Dulong.     Ann.  Chim.  Phys.  2,  317;  also  Schw.  18,  177;  also  Gilb.  58,  53. 
Dalton.     Ann,  Phil.  9,  186.     Ann.  Phil.  10,  38  &  83;  also  GUI),  58,  79. 
W.  Henry,  on  Nilroibs  Oxide,  Nitric  Acid  and  Ammonia,  Manchester  Mem, 

New  Ser,  Vol.  4;  also  Ann.  Phil.  24,  299  &  334;  also  Kastn.  Arch. 

3,  223. 
Pleischl.     Nitrom  Oxide,  Schw,  38,  461. 
Hess.     Nitrous  Acid.     Pogg.  12,  2.57. 
Peligot.   Binoxide  of  Nitrogen  or  Nitric  Oxide,   Ann.  Chim.  Phys.  54, 17; 

also  J.  Pharm.  19,  644;  also  Schw.  69,  341;  also  Ann.  Pharm. 

9,  259.     Nitrous  and  Hyponiiric  Acid.     Ann.  Chim,  Phys.  77,  58 

&  87;  the  latter  also  J.  pr.  Chem.  23,  124  &  504;  also  Ann.  PItarm, 

39,  327. 
Fritzsche.     Nitrous  and  Hyponitrous  Acid,  J.  pr.  Chem.  19,  179;  22, 14. 
Kuhlmann.     Ann.  Pharm.'29,  272;  39,  319. 


NITROGEN.  369 

Millon.     Nitric  Acid,     J.  Pliarm,  29,  179;  also  Cow.'pL  rend,  14,  904.   - 
Sulphite  of  Nitric  Oxide.     H.    Davy,   Researches,  317.— Pelouze.  Ann. 

Chim.  Fhys.   60,    151;    also   Pogg,   39,    181;   also  Ann.   Fharm. 

18,  240;  also  J.pr,  Chem.  11,  92. 
Sulphate  of  Nitric  Oxide:  Clement  &  Desormes.     Ann.  Chim.  59,  329; 

also  N.  Gehl  4,  457.— Dalton.     New  Sy^em,  2,  200.— Sir  H.  Davy. 

Elements.  1,  249. — Dbbereiner.     Schw.    8,  239. — Berzelius.     GUb. 

50,   388. — Gay-Lussac.     Ann.  Chim.  Phys.    1,  394. — W.   Hemy. 

Ann.  Phil.  27,  368;  also  J.  Pharm.   13,  113;  aho  Kastn.  Arch. 

8, 463;  abstr.  Pogg.  7,  135. — Gaaltier  de  Claubry.  Ann.  Chim.  Phys. 

45,  284;  also  Sc^iw.  63,  284;  also  Pogg.  20,  467.— Dana.    Phil.  Mag. 

J.  3,  115.— Bussy.     J.  Pharm.  16,  491;  also  N.  Tr.  23,  2,   118; 

abstr.  Pogg.    20,   174. — Thomson.     J.   Pharm.  22,   655. — De  la 

Prevostaye.     Ann.  Chim.  Phys.  73,  362;  also  J.  pr.  Chem.  21,  401; 

hhoN.  Br.  Arch.  24,  163.— H.  Rose.    Pogg.  47,  605.— A.  Rose. 

Pogg.  50,  161. 
Damas.     Solid  and  Liquid  Nitrous  Oxide.     J.  Pharm.  14,  411;  abst. 

Ann.  Pharm.  68,  224. 
Kolbe.     Formation  of  Nitric  Acid  in  Eudiometrical  experiments.    Ann. 

Pluzrm.  59,  208. 
Deville.     Anhydrous  Nitric  Acid.      Compt,  rend,  Feb.   17,  1849;  also 

Chem.  Gaz.  April  2,  1849. 

Atmospheric  Air: 

Lavoisier.  Crell.  Ann.  1788,  2,  426. — Berthollet.  Scher.  J.  1,  518. — 
Von  Humboldt.  Scher.  J.  5,  88  &  146.— De  Marty.  Scher.  J.  8,  57; 
abstr.  Gilb.  19,  389.— De  Marty.  N.  Gehl.  4, 146;  also  Gilb.  28,  422. 
— Humboldt  &  Gay-Lussac.  A.  Gehl.  5,  45;  also  Gilb.  20,  38. — 
Dalton.  Gilb.  27,  369.— Phil.  Mag.  J.  12,  397.— Hildebrandt. 
Schw.  14,  265. — Saussure.  Ann.  Chim.  Phys.  2,  199;  also  Cfilb. 
54,  217.— Ann.  Chim.  Phys.  3,  170.— Pibl.  Univ.  44,  23  &c  138; 
also  Pogg.  19,  391;  also  Schw.  60,  17  and  129. — Pibl.  Univ.  56, 130; 
also  J.  pr.  Chem.  3,  136.— iV.  Bibl.  Univ.  2,  170;  also  Fogg. 
28,  171;  slao  Ann.  Pharm.  19,  51. — Brunner.  Fogg.  20,  274;  24, 
569;  31,  1. — Ann.  Chim.  Phys.  78,  305. — Boussingault.  Ann. 
Chim.  Phys.  57,  148;  also  Pogg.  36,  456;  also  J.  pr.  Chem.  3,  151. 
—Dumas  &  Boussingault.  Compt.  rend.  12,  1005;  also  ^nn.  Chim. 
Phys.  78,  257;  abstr.  Pogg.  53, 391. — Dumas.  Compt.  rend.  14,  379. 
— Leblanc.  Compt.  rend.  14,  862;  also  N.  Ann.  Chim.  Phys.  5,  223. 
Regnault  &  Reiset.     Compt.  rend.  26,  4  and  155. 

Ammonia : 

C.  L.  Berthollet.     Crell.  Ann.  1791,  2,  169. 

Am.  Berthollet.     N.  Gehl.  7,  184;  also  Gilb.  30,  378. 

Th6nard.     Schw.  7,  299;  also  Gilb.  46.  267. 

Sir  H.  Davy.     N.  Geld.  7,  632;  also  Gilb.  31,  UV—Schw.  1,  302  8c  324; 

3,  334;  also  Gilb.  35,  151;  36,  180;  37,  S5.—N.  Gehl.  9,  507;  also 

Gilb.  33,  2^6.— Schw.  4,  209;  also  Gilb.  37,  155. 
W.  Henry.     Phil.  Transact.  1809,  2,  429;  also  Gilb.  36,  291. 
Berzelius.     Gilb.  36,  198;  37,  210;  38, 176;  46,  131. 
Bischof.     Schw.  42,  257;  45,  204. 
Faraday.     QuaH.  J.  ofSc.  19,  16;  also  Pogg.  3,  455;  also  Schw.  44,  341; 

also  Kastn.  Arch.  5,  442;  also  N.  Tr.  11,  1,  64. 

VOL.   II.  2  b 


370  NITROOEN« 

Bineau.    Ann.  Ckm.  Fhys.  67,  325;  75,  251;  also  J.  pr.  Chem.  15,  257; 

19,6. 
Kane.     Ammonia  and  Amidogen  Componnds:  Fogg.  42,  367. — Further: 

Ann.  Chim.  Phys.  72,  225  8c  337.— Alao  J.  Pr.  Chem.  15,  276.— 

Further:  PMl.  Mag.  J.  17,  20. 
J.  Davj.     Carbonate  of  Ammonia,    j^.  JEd,  Phil.  J.  16.  245. 
H.  Rose.     Carbonate  of  Ammonia.     Fogg,  46,  352. 
H.  Rose.     Anhydrous  Sulphite  of  Ammon.    Fogg.  33,  235;  42,  415. 
H.  Rose.     Anhydrous  Sulphate  of  Ammon.  Fogg.  32,81;  47,  471;  49,183. 
Ammonuhchloride  of  Phosphorus.     Sir  H.  Davy.     Gilb.  39,  6. — H.  Rose. 

Fogg.  24,  308;  28,  530. — ^Wohler  &  Liebig.  Ann.  Pharm.  11,  139. 
Ammonio-chloride  of  Sulphur.     Dumas.     Ann.  Chim.  Fhys.  49,  206. — 

Gregory.    J.  Pharm.  21,  315;  22,  301.— H.  Rose.     Fogg.  24,  307; 

52,  60. — Soubeiran.     Ann.  Chim.  Fhys.  67,  71;  also  J.  Pharm.  24, 

49. — Bineau.    Ann.  Chim.  Fhys,  70,  267. — Martens.  J.  Chim.  Med. 

13,  430.  . 

Compounds  of  Ammonium  vjith  Metallic  Iodides,  Bromides,  and  Chloride. 

Faraday.  QwiH.  J.  ofSc.  5,  74.— H.  Rose.  Fogg.  20,  154;  52,  57.— 

Pereox.  Ann.  Chim.  Fhys.  44,  315;  also  N.  Tr.  23,  3,  105.— Ram- 

melsberg.  Fogg.  58,  151;  55,  237. 
Compounds  of  Ammonia  wUh  Anhydrotts  Cxygen-saUs.     H.  Rose.  Fogg. 

20,  147. 
Phosphide  of  Nitrogen.    H.  Rose.  Fogg.  28,  529. — ^Wohler  &  Liebig. 

Ann.  Pharm.  11,  139. 
Compounds  containing  Fhospho7*us  and  Nitrogen.     Oerhardt.  N.  Ann. 

Chim.  Fhys.  18,  188.     Gladstone.  Qu.  J.  ofChem.  Soc.  2,  121. 
Sulphide  of  Nitrogen.     Gregory.  J.  Pharm.  21,  315. — ^Soubeiran.  Ann. 

Chim.  Fhys.  67,  71;  a&o  J.  Pharm.  24,  71;  also  Ann.  Pharm.  28, 

59  ;  also  J.  pr.  Chem.  13,  449. 
Iodide  of  Nitrogen.     Serullas.     Ann.  Chim.  Fhys.  42,  200;  also  Schw.  58, 

228;  also  Fogg.  17,  304. — Millon.  Ann.  Chim.  Fhys.  69,  78;  also,/. 

pr.  Chem.  17, 1. — Marchand.  J.  pr.  CJum.  19,  1. 
Bromide  of  NUrogen.     Millon.  Ann.  Chim.  Fhys.  69,  75. 
Chloride  qf  Nitrogen.     Dulong.    Schw.  8,  302;  also  GUb.  47, 43. — Porret, 

Wilson  &  Kirk.  Gilb.  47,  5^  and  69.— Sir  H.  Davy.  Phil.  Transact. 

3813, 1  and  242;  also  GUb.  A!7,  51.— Serullas.     Ann.  Chim.  Fhys.  69, 

75;  also  Schw.  58,  224;  also  Fogg.  17,  304.— Millon.    Ann.  Chim. 

Fhys.  69,  75. 
Metallic:  Nitrides.     Thenard.     Ann.  Chim.  85,61;  also  Gilb.  46,  267.— 

Savart.     Ann.  Chim.  Fhys.  37,  326;  also  Fogg.  13,  172;  also  N.  Tr. 

18,  1,  295. — Despretz.  Ann.  Chim.  Fhys.  42,  122;  bIbo  Schw.  58, 

218;  also  Fogg.  17,  296;  also  N.  Tr.  21,  1,  138.— Pfaff.   Fogg.  42, 

164.— Grove.  FhU.  Mag.  J.  18,  548;  19,  97;  alsoPo^^.  53,  363; 

54,  107. — Schrotter.    Ann.  Pharm.  37, 1 28.— Plautamour.   N.  Bill. 

Univ.  32,  339;  also  Ann.  Pharm.  40,  115;  also  J.  pr.  Chan.  24, 

220.  

Stiekstof,  Salpeterstqf,  Azote,  Nitrogene,  Alcaligene,  Septone,  Azotum, 
Nitrogenium. — Nitrogen  gas,  Stickgas,  Stickstoffgas,  Salpeterstofgas, 
Stichluft,  phlogistisirte,  verdoriene  luft,  Gas  astote,  Mofette  atmospherique, 
Air  vici^. 

History.  It  has  been  known  from  very  early  times  that  the  air  is 
vitiated  by  the  processes  of  combustion  and  respiration,  and  rendered 


NITROGEN.  371 

unfit  for  their  further  continnanoe.  As  long  as  the  air  was  considered  a 
simple  substance,  this  fact  was  explained  on  the  supposition  that 
phlogiston  was  imparted  to  it  by  the  burning  body.  Rutherford,  in 
1772,  showed  that  in  the  process  of  respiration  the  air  is  by  no  means 
simply  converted  into  carbonic  acid,  but  that  at  the  same  time,  an  irres- 
pirable  air  of  a  peculiar  nature  is  left  behind.  Before  1777,  Scheele 
separated  the  oxygen  of  the  air  from  the  nitrogen ;  he  likewise  disco- 
vered, almost  simultaneously  with  Lavoisier,  that  the  atmosphere  is  a 
mixture  of  these  two  gases. 

From  the  nitrates,  a  class  of  substances  known  from  very  early  time&— 
and  more  particularly  from  saltpetre — the  Arabians  first,  and  afterwards 
the  alchemists  appear  to  have  obtained  aqueous  Citric  acid  (chiefly  by 
heating  a  mixture  of  saltpetre  with  clay,  till  Glauber  replaced  the  latter 
by  sulphuric  acid).  Priestley  very  early  remarked  that  a  mixture  of 
oxygen  and  nitrogen  gases  contracts  and  yields  an  acid  when  electrified ; 
Cavendish,  however,  in  1-785,  first  proved  that  the  two  gases  unite  com- 
pletely and  produce  nitric  acid.  HyponUric  add  was  first  noticed  by 
Scheele  in  1774,  and  afterwards  examined  more  particularly  by  Priestley, 
BerthoUet,  Davy,  Thomson,  Daltou,  Berzelius,  Gay-Lussac,  and  Dulong, 
the  three  latter  chemists  distinguishing  from  this  acid  the  Nitrous  aetd 
hitherto  confounded  with  it.  Nitrous  gas  was  first  obtained  by  Hales^ 
and  afterwards  more  particularly  examined  by  Priestley,  Fontana, 
Humboldt,  Davy,  Dalton,  Gay-Lussac,  and  others.  Priestley,  in  1776, 
discovered  Nitrotts  oxide  gas,  which  was  examinedi  n  1 785  by  BerthoUet, 
in  1793  by  the  Dutch  chemists,  who  investigated  its  composition,  in  1800 
by  Sir  H.  Davy,  and  in  1 823  by  W.  Henry  and  Pleischl. 

The  preparation  of  Sal-ammoniac  was  known  even  to  the  ancient 
Egyptians.  Carbonate  of  ammonia,  which  is  evolved  either  on  heatinc^ 
sal-ammoniac  with  carbonate  of  lime,  or  from  animal  substances  exposed 
to  heat,  appears  to  have  been  known  to  the  Arabians.  The  alchemists 
were  acquainted  with  Solution  of  Caustic  Ammonia.  Priestley  disco- 
vered Ammaniacal  gas,  and  observed  its  decomposition  by  electricity  and 
by  metallic  oxides;  Scheele  showed  that  it  is  composed  of  nitrogen  and 
phlogiston,  by  which  name  hydrogen  is  to  be  understood — as  was  subse- 
quently proved  by  C.  L.  BerthoUet,  who,  in  concert  with  Am.  BerthoUet 
and  W.  Henry,  determined  more  particularly  the  proportions  in  which 
the  elements  of  this  substance  are  combined.  The  compound  of  ammonia 
with  phosphorus  was  examined  in  1800  by  Bockmann  and  A.  Vogel;  its 
compounds  with  phosgene  and  with  chloride  of  boron,  by  J.  Davy :  with 
chloride  of  phosphorus,  by  Sir  H.  Davy  and  H.  Rose ;  with  chloride  of 
sulphur,  by  Thomson,  Dumas,  Gregory,  Soubeiran,  Bineau ;  with  oxy- 
chlorosulphide  of  carbon,  by  Berzelius;  with  metallic  chlorides,  by 
Faraday,  Persoz,  and  H.  Rose;  and  with  anhydrous  oxygen  salts,  by 
H.  Rose. 

Phosphide  of  Nitrogen  was  discovered  and  examined  in  1833  by  H. 
Rose;  Sulphide  of  nitrogen,  in  1835,  by  Gregory,  and  more  accurately, 
in  1838,  by  Soubeiran;  Iodide  of  nitrogen,  in  1811,  by  Coortois;  Bro- 
mide  of  nitrogen,  in  1838,  by  Millon;  Chloride  of  nitrogen,  in  1812,  by 
Dulong,  who  lost  an  eye  in  the  investigation.  The  existence  of  Metallic 
Nitrides  was  proved  especially  by  Savart,  Despretz,  Pfafi*,  Schr5tter,  and 
Plantamour. 

Sources.  As  nitrogen  gas,  constituting  0*79  of  the  volume  of  the 
atmosphere ;  also  in  the  air-bladders  of  fish;  and  in  other  cavities  in  the 

2  B  2 


372  NITROGEN. 

bodies  of  animals  and  vegetables ;  in  the  salts  of  nitric  acid,  and  of  am- 
monia; in  a  vast  namber  of  organic  compounds^  especially  in  those 
belonging  to  the  animal  kingdom. 

Preparation, — 1.  A  portion  of  the  oxygen  contained  in  a  confined  portion 
of  atmospheric  air  is  removed  by  the  slow  or  rapid  combustion  of  phospho* 
rusj  by  moistened  alkaline  sulphides  or  their  aqueous  solutions;  by  a 
mixture  of  iron  filings  and  sulphur  moistened  with  water;  by  prolonged 
agitation  with  a  liquid  amalgam  of  lead ;  by  moistened  charcoal ;  by  excess 
of  nitric  oxide  gas,  the  remaining  portion  of  which  is  afterwards  removed 
by  agitation  with  solution  of  green  vitriol;  or  by  some  other  substance,  which 
forms  a  liquid  or  solid  gaseous  compound  with  oxygen, — the  carbonic  acid 
gas  being  lastly  absorbed  by  a  caustic  alkali.  I)umas  &  Boussingault 
{Compt  rend,  12,  1005)  pass  atmospheric  air,  freed  from  carbonic  acid 
Dy  caustic  potash  and  from  aqueous  vapour  by  oil  of  vitriol,  over  red- 
hot  finely  divided  copper  obtained  by  reducing  oxide  of  copper  with 
hydrogen  gas.  Brunner  {Pogg.  27,  4)  passes  air  thoroughly  dried  by 
means  of  chloride  of  calcium  over  red-hot  finely  divided  iron  (re- 
duced from  the  ses({ui-oxidc  by  a  current  of  hydrogen  gas);  a  trace  of 
moisture  may  in  this  case  cause  the  nitrogen  to  be  contaminated  with 
hydrogen  gas. — 2.  B^r  decomposing  ammonia  with  chlorine  {Sch,  22); 
either  by  passing  chlorine  gas  into  solution  of  ammonia,  or  by  introducing 
fragments  of  sal-ammoniac  into  a  solution  of  chloride  of  lime. — 3.  By 
decomposing  ammonia  with  an  oxygen-compound  of  nitrogen.  Pelouze 
{Ann,  Chim.  Phys,  77,  49)  saturates  oil  of  vitriol  with  nitric  oxide  gas,  then 
adds  sulphate  of  ammonia,  and  heats  to  a  temperature  of  IGO""  (230"  F.)  : 
in  this  manner,  very  pure  nitrogen  gaa  is  obtained  Emmet  {LiU,  A  nn.  J. 
18,  259  ;  also  Ann,  Pharm,  18,  168)  heats  nitrate  of  ammonia  in  a  retort 
till  it  fuses;  then,  having  attached  a  piece  of  zinc  to  a  wire,  introduces  it 
into  the  fused  salt  to  such  a  depth  as  to  cause  a  moderately  rapid  disen- 
gagement of  nitrogen.  If  the  zinc  were  completely  immersed,  the  action 
would  be  too  violent.  IT  Carenwinder  (N,  Ann.  Chim,  Phys.  26,  296) 
heats  a  solution  of  nitrite  of  potash  mixea  with  sal-ammoniac: 

KO,NO>  +  NH^  HCl  =  KCl  +  4H0  +  2N. 
The  solution  of  nitrite  of  potash  is  prepared  by  passing  the  nitrous  gas 
evolved  by  heating  1  part  of  starch  with  10  parts  of  nitric  acid  into  a 
solution  of  caustic  jpotash  of  specific  gravity  1-38,  till  the  liquid  becomes 
decidedly  acid,  and  then  adding  a  suflicient  quantity  of  caustic  potash  to 
restore  the  alkaline  reaction.  The  solution  of  nitrite  of  potash  thus 
obtained  may  be  preserved  without  alteration.  On  mixing  this  liquid 
with  3  times  its  bulk  of  concentrated  solution  of  sal-ammoniac,  and  gently 
heating  the  mixture  in  a  small  flask,  nitrogen  gas  is  evolved  in  abundance 
and  with  ffreat  regularity.  The  gas  thus  obtained  is  perfecUy  pure.  The 
same  result  naay  be  obtained  by  heating  a  solution  of  nitrite  of  ammonia: 
but  that  salt  is  diflacult  to  prepare.  IT— 4.  By  heating  animal  substanoesj 
such  as  muscle,  in  dilute  nitric  acid  to  a  temperature  of  30**  (86**  P.)  and 
removing  the  nitric  oxide  disingaged  at  the  same  time,  by  means  of  a 
solution  of  green  vitriol. 

PropeHies.  Colourless  gas.  (For  the  specific  gravity  and  refractive 
power,  vid,  I.,  280  and  95).  Incombustible,  and  incapable  of  sustaining 
the  combustion  of  other  bodies ;  destitute  of  odour,  taste,  or  action  on  veg^ 
table  colours.  It  may  be  breathed  for  a  time,  but  does  not  support  rewi- 
ration;  it  is  only  negatively  hurtful. 


NITROUS  OXIDE.  373 

Comhinatums.  Nitrogen  manifests  but  few  and  very  feeble  affi- 
nities, whether  towards  highly  electro-positive  elements  as  hydrogen,  or 
towards  highly  electro-noffative  elements  as  oxygen  and  chlorine.  On 
the  contrary,  it  has  probably  the  greatest  affinity  of  all  ponderable  bodies, 
for  heat,  with  which  it  constantly  tends  to  form  a  gas.  Consequently 
many  of  its  compounds  are  decomposed  by  slight  causes,  with  extreme 
suddenness,  the  nitrogen  being  disengaged  m  the  gaseous  form,  and  often 
producing  the  most  violent  explosions. 

Atomic  weight  of  nitrogen,  according  to  Berzelius  =  7*09  (or  14*18), 
according  to  Dumas.  (Campt  rend.  14,  546)  =  7  (or  14.) 


Nitrogen  and  Water. 

Water  at  a  temperature  of  18°  (64*4°  F.)  absorbs,  according  to  Th. 
Saussnre  -^j  according  to  Dal  ton,  ^  of  its  volume  of  nitrogen  gas. 


Nitrogen  and  Oxygen. 

Combination  takes  place  very  slowly,  under  peculiar  circumstances 
only,  and  without  perceptible  disengagement  of  light  or  heat. 


A.     Nitrous  Oxide.    NO. 

Protoxide  of  Nitrogen^  Stickstoffoxydvl,  Protoxyde  ^ Azote,  Oxyde  nitreux, 
Oxydirtes  Stickgas^  Oxyduliries  Salpeterstqffgas,  Dephlogistisirtes  Sal- 
peiergas,  Laughing  gas,  Wonnegas,  Gas  oxyde  d* azote,  Gas  protoxyde 
(Tazote. 

Formatiofi.  This  compound  cannot  be  formed  by  the  direct  mixture  of 
nitrogen  and  oxygen,  but  is  produced  by  the  decomposition  of  the  higher  oxy- 
gen compounds  of  nitrogen :  for  instance,  on  mixing  nitric  oxide  gas  with 
hydro-sulphuric  acid,  dry  or  moist  liver  of  sulphur,  moistened  iron  or  zinc 
filings,  hydrated  protosulphide  of  iron  (or  hydrosulphate  of  ferrous  oxide) 
salts  of  sulphurous  acid  in  solution,  or  protochloride  of  tin;  by  heating  ni- 
trate of  ammonia,  (Scheme  12);  and  by  dissolving  zinc,  tin,  or  iron  in  dilute 
nitric  acid.  (Scheme  25.)  Copper  treated  with  nitric  acid  of  specific  gravity 
1*217,  also  yields  nitrous  oxide  gas  mixed  with  a  small  quantity  of  nitric 
oxide,  provided  the  temperature  be  kept  below  —10°.  (Millon.) 

Preparation, — 1.  In  the  gaseous  form:  a.  Neutral  nitrate  of  ammonia 
free  from  hydrochloric  acid,  is  heated  in  a  glass  retort  (App,  34)  to  a 
temperature  between  170**  and  260=»  (338'' — 500®  F.)  One  pound  of 
nitrate  of  ammonia  yields  4  cubic  feet  of  gas.  If  too  strong  a  heat  be 
applied,  a  violent  explosion  may  take  place.  At  a  higher  temperature 
than  the  above,  nitric  oxide  gas  is  also  eiven  ofi*,  and  must  then  be  sepa- 
rated by  a  solution  of  green  vitriol.  If  chloride  of  ammonium  is  present 
in  the  nitrate,  chlorine  gas  is  disengaged,  and  must  be  removed  by  caustic 
potash.  Grouvelle's  method  (Ann,  Chim,  Phys,  17,  351 ;  also  §chw,  33, 
236),  which  consists  in  heating  a  mixture  of  3  partei  of  nitrate  of  jMtash 
with  1  part  of  chloride  of  ammonium,  instead  of  nitrate  of  ammonia,  yields 
a  gaseous  mixture  of  chlorine,  nitrogen,  and  nitric  oxide,  which,  according 


874  NITROGEN. 

to  Pleischl,  contains  a  small  quantity  of  nitrons  oxide,  bnt  according  to 
Soabeiran  (j.  Pkarm,  13,  321 ;  also  Fogg.  13,  282),  not  even  a  trace. 

6.  Bj  dissolving  zinc  in  very  dilute  nitric  acid.  According  to 
Grotthuss  {Schw.  32,  271)  andPleischl,  a  perfectly  pare  gas  is  obtained  in 
this  manner;  according  to  the  latter,  the  best  mixture  for  the  purpose  ia 
1  part  of  acid  of  specific  gravity  1  *2,  with  an  equal  weight  or  more  of 
water;  with  a  stronger  acid,  greater  heat  is  evolved  during  the  solution, 
and  the  nitrous  oxide  gas  becomes  contaminated  with  nitric  oxide. 

The  gas  is  received  over  water,  or  brine  (which  absorbs  less  of  it),  or 
over  mercury. 

2.  In  the  liquid  stale,  cr.  Perfectly  dry  nitrate  of  ammonia  placed  at 
one  end  of  a  bent  glass  tube  hermetically  sealed,  is  heated  till  the  whole 
has  distilled  over  into  the  cold  end;  then  this  end  is  heated;  and  so 
on  two  or  three  times,  till  the  greater  portion  of  the  salt  is  decomposed. 
In  the  cooler  end,  two  strata  of  liquid  condense,  the  lower  of  which 
is  water  containing  nitrous  acid  and  nitrous  oxide  in  solution;  the 
upper,  liquid  nitrous  oxide.  The  apparatus  is  very  liable  to  burst  with 
extreme  violence,  so  that  the  greatest  caution  is  required  iu  using  it. 
(Faraday.)  Niemann  (Pr.  Arch.  36,  177)  did  not  succeed  in  this  experi- 
ment. If  the  heat  is  applied  till  the  manometer  indicates  a  pressure  of 
75  atmospheres,  water  alone  passes  over;  at  a  temperature  above  the 
melting  point  of  lead,  the  pressure  increases  to  90  atmospheres,  or  water 
alone  pajases  over,  the  greater  part  of  the  nitrate  of  ammonia,  which,  under 
this  powerful  pressure,  is  less  readily  decomposed  by  heat,  remaining  in 
the  heated  branch  of  the  tube;  on  still  further  increasing  the  heat,  explo- 
sion ensues. — 6.  By  mechanical  compression  of  the  gas.  (Natterer,  Pogg, 
12,  132.) 

IT  3.  In  the  solid  state,  a.  By  exposing  liquid  nitrous  oxide  to  the 
cold  produced  by  the  carbonic  acid  bath  in  vacuo  (I.,  287),  the  freezing 
point  being  about  —100°  C.  or  —150°  F.  (Faraday.) — b.  When  liquid 
nitrous  oxide  is  allowed  to  escape  into  the  air  by  opening  the  stop-cock 
of  the  vessel  in  which  it  has  been  condensed,  the  first  portion  which 
escapes  is  reduced  to  the  solid  state.  (Dumas.) 

Properties, — 1.  In  the  solid  state.  White,  snow-like  mass,  which  when 

E laced  on  the  hand,  melts,  evaporates  suddenly,  and  produces  a  blister 
ke  a  burn.  (Dumas,  J.  Pharm,  14,  411.)  Mixed  with  bisulphide  of  car- 
bon in  vacuo,  it  depresses  the  thermometer  to  —140°  C.  or  —240°  F. 
(Natterer.  Ann.  Pharm.  54,  254.) 

2.  In  the  liquid  state.  Colourless,  very  mobile;  a  single  drop  of  it 
placed  on  the  hand,  produces  a  wound  like  a  bum.  Metals  dipped  into 
this  liquid  produce  a  hissing  noise,  just  as  when  red-hot  iron  is  plunged 
in  water.  Potassium  swims  on  its  surface  without  alteration :  so  likewise 
do  charcoal,  sulphur,  phosphorus,  and  iodine.  Ignited  charcoal  swims  on 
the  surfifice  and  burns  with  vivid  light.  The  liquid  is  miscible  with  ether 
and  alcohol.  Sulphuric  and  nitric  acid  are  immediately  frozen  by  con- 
tact with  it.  Water  also  freezes,  but  at  the  same  time  causes  the  liquid 
nitrous  oxide  to  evaporate  with  a  degree  of  rapidity  almost  amounting  to 
explosion.  (Dumas.)  IT  Refracting  power,  less  than  that  of  any  other 
liquid.  (Faraday.) 

3.  In  the  gaseous  state.  Colourless  gas.  [Tension,  specific  gravity 
and  refractive  power,  I.,  261,  280,  and  95.]  It  has  a  slight,  agreeable 
odour,  and  a  sweet,  pleasant  taste.  It  may  oe  respired  for  a  short  time, 
not  exceeding  four  minutes,  and  then  produces  very  remarkable  efiects. 


NITROUS  OXIDE.  375 

mostly  of  an  intoxicating  character.  Wedgewood^  Sir  H.  Davy,  and 
others,  were  agreeably  affected  by  it,  experiencing  great  hilarity  and 
intoxication,  and  ultimately  loss  of  consciousness :  these  symptoms  were 
foUowed  by  exhaustion.  With  Thenard,  paleness  and  loss  of  strength 
ensued,  even  to  fainting.  Vauquelin  experienced  very  disagreeable,  suffo- 
cating sensations;  Proust,  confusion  of  sight,  double  vision,  anxiety,  faint* 
ing,  and  unpleasant  sensations;  Cardone  {J,  Chim.  Med,  2.  132),  violent 
pain  in  the  temples,  which  lasted  for  an  hour;  confused  sight  with  double 
vision;  indistinct  hearing,  amounting  at  intervals  to  deafness;  violent 
perspiration  over  the  whole  body;  a  soapy  taste  in  the  mouth  at  first, 
afterwards  sweet,  and  lastly  acid,  with  drvness  in  the  throat,  great  incli- 
nation to  talk  and  laugh,  and  finally,  melancholy  and  drowsiness;  after 
which  the  effects  ceased.  In  the  case  of  one  person,  it  even  produced 
delirium,  with  violent  movements  similar  to  the  St.  Vitus'  dance,  which 
continued  for  several  days  (Schw.  36,  244).  Animals,  when  immersed 
in  the  gas,  becomes  restless  after  a  while,  and  die  after  a  longer  interval. 

The  gas  is  not  combustible :  a  candle  introduced  into  it,  bums  with 
greater  brilliancy  than  in  the  air :  a  flowing  match  introduced  into  a  jar 
of  the  gas  bursts  into  flame.  When  mixed  with  nitric  oxide  gas,  it  neither 
produces  red  vapours,  nor  suffers  diminution  of  volume.  It  has  no  effect 
on  vegetable  colours. 

Calculation.  H.Davy.      Deiman.  Vol.  Sp.  gr. 

N  14  63-6  63-3  62-5  Nitrogen  ga« 1  0*9706 

O  8  36-4  36-3  77*5  Oxygen  gas i  0*5546 

NO    ....  22  1000  100*0  100*0  Nitrons  oxide  gas  1  1*5252 

(N«0  =  2  .  88-52  +  100  =  277*04.     BerzeUns.) 

Decompositions. — 1.  By  long  continued  electrization,  or  when  passed 
through  an  ignited  porcelain  tube,  nitrous  oxide  gas  is  resolved — ^with 
diminution  of  volume  amounting  to  about  0*1,  and  production  of  a  small 
quantity  of  hyponitric  acid — into  a  mixture  of  oxygen  and  nitrogen  gases. 
(Priestley.) 

2.  When  mixed  with  one  volume  of  hydrogen  gas  and  exploded  by 
the  electric  spark,  or  when  passed  through  a  red  hot  tube,  one  volume  of 
nitrous  oxide  is  converted  into  water  and  one  volume  of  nitrogen  gas ; 
with  a  smaller  quantity  of  hydrogen,  nitric  acid  is  also  produced. 
(Priestley,  Sir  H.  Davy,  W.  Henry.)  Spongy  platinum  becomes  ignited 
in  the  above  mixture,  and  converts  it  into  water  and  nitrogen  gas. 
(Dbbereiner,  Dulong  <jb  Thenard.)  When  excess  of  hydrogen  is  present, 
ammonia  is  also  formed.  (Kuhlmann.)  (Vid.  Ammonia.)  Nitrous  oxide 
gas  likewise  explodes  by  the  electric  spark,  or  at  a  red  heat,  when  mixed 
with  ammoniacal  gas  or  with  carburetted,  phosnhuretted,  or  sulphuretted 
hydrogen,  yielding  nitrogen  gas,  water,  and  carbonic,  phosphorous,  or  sul- 
phurous acid.  Spontaneously  inflammable  phosphuretted  hydrogen  gas  ex- 
plodes with  nitrous  oxide,  even  at  ordinary  temperatures  (Th6nard);  ac- 
cording to  Berzelius,  however,  the  mixture  does  not  explode  tiUit  is  exposed^ 
to  the  air,  whereby  the  phosphuretted  hydrogen  is  set  on  fire,  or  till  an 
electric  spark  is  passed  through  it.  A  mixture  of  1  volume  of  phosphuretted 
hydrogen  gas  with  3  volumes  of  nitrous  oxide  yields  water,  phosphoric 
acid,  and  3  volumes  of  nitrogen  gas.  (Thomson.)  The  mixture  explodes 
with  great  violence  when  the  electric  spark  is  passed  through  it;  and  if 
the  nitrous  oxide  is  in  excess,  4  volumes  of  phosphuretted  hydrogen  gas 
are  decomposed  with  21  volumes  of  nitrous  oxide  gajs,  3  volumes  of  oxygen 
combining  with  the  hydrogen,  and  7'5  volumes  with  the  phosphorus  in 


/ 


376  NITROGEN. 

the  pliospliareited  hydrogen  gas.  (Dumas.)  If  wo  assume  with  H.  Rose 
that  4  Tolumes  of  phosphuretted  hydrogen  gas  contain  1  volume  of  vapour 
of  phosphorus  and  6  volumes  of  hydrogen  gas,  then  5  volumes  of  oxygen 
will  combine  with  the  phosphorus,  and  3  volumes  with  the  hydrogen,  so 
that  4  volumes  of  phosphuretted  hydrogen  gas  will  require  8  volumes  of 
oxygen  gas,  contained  in  16  volumes  of  nitrous  oxide  gas. — 3.  A  mixture 
of  1  volume  of  carbonic  oxide  gas  with  rather  more  than  1  volume  of 
nitrous  oxide,  yields,  when  exploded  by  the  electric  spark,  1  volume  of 
carbonic  acid,  rather  more  than  1  volume  of  nitrogen,  and  a  small  quan- 
tity of  free  oxygen,  because  the  excess  of  nitrous  oxide  is  resolved  by 
the  heat  into  its  gaseous  elements.  (W.  Henry.) 

4.  Ignited  charcoal  bums  in  nitrous  oxide  more  vividly  than  in  com- 
mon air,  1  volume  of  the  gas  being  converted  into  I  volume  of  nitrogen 
gas  and  a  half  volume  of  carbonic  acid  gas.  (Sir  H.  Davy.)  Heated  boron 
bums  in  the  gas,  forming  boracic  acid  and  separating  the  nitrogen.  Phos- 
phoras  may  be  volatilized  in  an  atmosphere  of  the  gas,  or  even  touched 
with  a  red  hot  iron,  without  being  inflamed ;  but  if  touched  with  a  white 
hot  iron  or  first  set  on  fire  in  the  air  and  then  introduced  into  the  gas,  it 
bums  almost  as  vividly  as  in  oxygen  gas,  though  for  a  shorter  time,  and 
produces  phosphoric  acid,  with  separation  of  nitrogen  gas  and  formation 
of  a  small  quantity  of  hyponitric  acid.  (H.  Davy.)  Sulphur  brought 
into  a  state  of  feeble  combustion  in  the  air,  is  extinguished  by  immer- 
sion in  nitrous  oxide;  when  in  full  combustion,  however,  it  continues 
to  burn  with  a  rose-coloured  flame,  and  is  converted  into  sulphurous  acid. 
(Davy.)  Boron,  phosphorus,  and  sulphur,  under  these  circumstances, 
liberate  1  measure  of  nitrogen  for  each  measure  of  nitrous  oxide. 

5.  Potassium  and  sodium,  gently  heated  in  nitrous  oxide,  bum  at 
first  with  violent  incandescence,  and  form  peroxides^  which,  when  further 
heated,  decompose  the  gas,  and  are  converted  into  salts  of  nitrous  acid^ 
while  nitrogen  and  nitric  oxide  gases  remain  behind.  (Gay-Lussac 
&  Th^nard.)— 6.  An  intensely  heated  steel  spring  bums  in  this  gas 
almost  as  brilliantly  as  in  oxygen  (Priestley);  similarly,  manganese,  zinc 
and  tin,  in  a  state  of  ignition  are  oxidized  in  the  gas,  a  volume  of  nitrogen 
being  separated,  equal  to  that  of  the  nitrous  oxide  (H.  Davy.) 

Fuming  nitric  acid  introduced  into  the  gas  diminishes  its  volume, 
in  a  manner  not  yet  explained.  (Demian,  Sdter.  J,  7,  260.) 

Hypochlorous  acid  gas  does  not  afiect  it  at  ordinary  temperatures. 
(Balard.)  Salts  of  ferrous  or  stannous  oxide,  salts  of  hydrosulphuric 
and  sulphurous  acid,  and  nitric  oxide  gas,  do  not  separate  oxygen  from 
nitrous  oxide. 

Combinations,^^.  One  volume  of  water  at  ordinary  temperatures 
absorbs,  according  to  W.  Henry,  from  0'78  to  0-16;  according  to  Dalton, 
O'SO;  according  to  Th.  Saussure,  0*76;  according  to  Sir  H.  Davy,  0*54; 
and  according  to  Pleischl,  at  a  temperature  of  18%  0  708  vol.  of  nitrous 
oxide  gas ;  the  solution  has  a  sweetish  taste.  At  a  boiling  heat,  the  gas 
is  evolved  unchanged.  (Priestley.) 

It  is  not  absorbed  by  aqueous  solutions  of  ferrous  salts. 

h.  Nitrous  oxide  is  absorbed  by  alcohol  or  ether,  and  by  oils  either 
fixed  or  volatile. 


NITRIC  OXIDE.  377 


B.    Nitric  Oxide.     N0^ 

Bioxide  of  Nitrogen^  Binoxide  of  Nitrogen,  DetUoxide  of  Nitrogen,  Stick' 
stoffoxyd,  Oxyde  nitric,  Oxyde  d! Azote,  Deutoxyde  ^ Azote,  Bi-oxyde 
(TAzote^ — Nitric  oxide  gas,  Stichoxyd-gas,  Salpetergas,  Oxydirtes,  Sal- 
peterstofgas.  Nitrous  air,  Nitrose  Luft,  Gas  nitreux,  Gas  deutoxyde 
cT Azote,  Gas  nitrosum. 

Formation. — 1.  When  ammoniacal  gas  is  passed  over  peroxide  of 
manganese  or  calcined  green  vitriol  heated  to  redness  in  a  ^n-barrel. 
(Milner,  CrelL  Ann,  1,7951,  554.) — 2.  When  nitrons,  hyponitric,  or  nitric 
acid,  is  brought  in  contact  at  a  temperatnre  below  redness  with  charcoal, 
phosphorus,  sulphur,  organic  substances,  and  with  various  metals. 

Preparation.  By  dissolving  copper  {Sch,  24),  bismuth,  lead,  silver, 
or  mercury  in  nitric  acid  of  specific  gravity  from  1-2  to  1*3.  The  more 
dilute  the  acid,  and  the  lower  the  temperature  at  which  it  acts,  the  less 
is  the  gas  contaminated  with  free  nitrogen.  Copper  treated  with  dilute 
acid, — if  the  rise  of  temperature  be  prevented  by  a  freezing  mixture — 
yields  the  purest  gas,  perfectly  absorbed  by  a  solution  of  green  vitriol. 
(Millon,  Compt,  rend,  1 4,  908.)     The  gas  is  received  over  water. 

When  concentrated  nitric  acid  is  heated  with  copper  in  a  sealed  bent 
tube, — a  blackish  green  stratum  of  liquid,  of  specific  gravity  about  1*0  or 
1*2  appears  above  the  copper  solution,  as  soon  as  the  pressure  amounts 
to  20  atmospheres.  This  liquid,  when  shaken,  separates  not  into  drops 
but  into  flakes,  which  however  soon  reunite;  when  gently  heated  it 
distils  over  into  the  cold  empty  branch  of  the  tube  and  appears  of  a 
bluish  green  colour.  If  the  pressure  in  the  tube  increases  to  more 
than  50  atmospheres,  the  liquid  entirely  disappears.  Mercury  cannot 
be  used  instead  of  copper  in  this  cajse,  because  the  mercurial  solution 
absorbs  the  nitric  oxide  gas,  so  that  the  pressure  never  rises  above  two 
atmospheres.  (Niemann,  N,  Br,  Arch,  4,  26.) 

Properties,  Colourless  gaa.  (For  its  specific  gravity  and  refractive 
power  see  I.,  280  and  95.)— Inhaled  in  a  pure  state  it  destroys  life.  Does 
not  redden  litmus.  Is  not  combustible.  Supports  the  combustion  of 
but  few  substances,  not  that  of  a  candle,  for  instance.  Forms  yellow- 
ish red  vapours  in  the  air.  It  is  copiously  absorbed  by  a  solution  of 
ferrous  sulphate,  forming  a  dark-brown  coloured  liquid.  It  imparts 
a  red  colour  to  oil  of  vitriol  containing  a  small  quantity  of  ferrous  sul- 
phate, and  a  violet  colour  to  oil  of  vitriol  containmg  sulphate  of  copper. 
(Desbassins  de  Richemont.  J.  Chim,  Med,  11,  504.) 

Calculation.  H.  Davy.       Lavoisier.      Dalton.  Berzelius. 

N      14 46-67  42-3  32 42 46*754 

20      16 53-33  57-7  68 58 53-246 

NO* 30 10000  lOO-p  100 100 100-000 

Vol.         Sp.gr.      Vol.  Sp.gr. 

Nitrogen  gas      1  0*9706  =  i  0-4853 

Oxygen  gas 1  11093  =  i  0*5546 

Nitric  oxide  gas  2  20799  =  1  10399 

(NO  =s  88*52  +  100  ===  188*52.    BeneUas.) 


378  NITROGBN. 

Decompositions.  1.  By  a  prolonged  succession  of  electric  sparks 
(Priestley),  or  by  transmission  throagh  an  ignited  tube  containing  pla- 
tinum wire,  (Gay-Lussac),  nitric  oxide  gas  is  resolved  into  nitrogen  gas 
and  hyponitrio — or,  if  water  be  present — nitric,  acid. — 2.  When  kept 
for  3  months  in  contact  with  a  concentrated  solution  of  caustic  potash^ 
it  is  resolved  into  ^  vol.  of  nitrous  oxide  gas,  and  nitrous  acid,  which 
latter  combines  with  the  potash.  (Gay-Lussac.) 

3.  A  mixture  of  2  volumes  of  nitric  oxide  gas  and  1  volume  of 
sulphurous  acid  gas,  placed  over  water  for  a  few  hours,  condenses  to 
aqueous  sulphuric  acid  and  1  volume  of  nitrous  oxide  gas.  (Pelonze, 
Ann.  Chim.  Pkys.  60, 162.) 

SO«  +  N0«  =  S0>  +  NO. 

Moistened  alkaline  sulphites,  protochloride  of  tin,  and  anhydrous  sul- 
phide of  potassium  reduce  2  volumes  of  nitric  oxide  gas,  at  ordinary 
temperatures,  to  1  volume  of  gaseous  nitrous  oxide,  by  absorbing 
1  atom  of  oxygen. — 4.  A  mixture  of  equal  volumes  of  hydrosnlphuric 
acid  and  nitric  oxide,  is  resolved  in  a  few  hours,  into  a  small  quantity  of 
nitrous  oxide  gas  and  hydrosulphite  of  ammonia:  according  to  Thomson, 
this  effect  is  most  quickly  produced  when  the  gases  are  dry.  In  a  similar 
manner,  solutions  of  alkaline  hydrosulphates  and  hydrosulphites,  also 
moistened  iron  (see  Thomson,  Ann.PkU.  15, 225)  and  zinc  filings  introduced 
into  nitric  oxide  gas,  give  rise,  in  the  course  of  a  few  days,  to  the  formation 
of  nitrous  oxide  gas  and  ammonia, — the  hydrogen  uniting  partly  with  the 
oxygen  of  the  nitric  oxide  to  form  water,  and  partly  with  the  nitrogen, 
to  form  ammonia.  Aqueous  solutions  of  alkaline  hydrosulphates  convert 
nitric  oxide  gas  into  a  mixture  of  nitrous  oxide  and  nitrogen  gases ;  a 
mixture  of  iron  filings  and  sulphur  moistened  with  water  converts  100 
measures  of  nitric  oxide  gas  into  44  measures  of  pure  nitrogen.  (Berthollet, 
Siat.  Ohim.  2,  153  <fe  161.^ 

5.  A  mixture  of  nitnc  oxide  and  hydrogen  (in  equal  volumes)  ex- 
plodes, according  to  Fourcroy  and  Thomson,  when  passed  through  a 
red-hot  tube;  according  to  Berthollet,  however  {Stat.  Chira.  2,  145,)  no 
explosion  takes  place;  nor  by  the  electric  spark.  (H.  Davy.)  The 
mixture,  if  set  on  fire  in  the  air,  does  not  explode  but  bums  with  a  white 
(or,  according  to  Berzelius,  a  green)  flame,  with  formation  of  hyponitric 
acid  vapour;  hence  it  would  appear  that  the  hydrogen  burns  only  at  the 
expense  of  the  atmospheric  oxygen.  An  ignited  jet  of  hydrogen  gas 
thrown  into  an  atmosphere  of  nitric  oxide  does  not  continue  to  burn. 
(Waldie,  Phil.  Mag.  J.  13,  89.)  According  to  Dulong  &  Thenard  and 
Kuhlmann,  cold  spongy  platinum  converts  the  mixture  into  water  and 
ammonia ;  but  according  to  Dobereiner,  no  such  effect  takes  place. 

If  a  mixture  of  2  measures  of  nitric  oxide  and  5  measures  of  hydrogen 
gas  be  passed  in  a  fine  stream  throagh  the  neck  of  a  small  tubulated 
retort,  directly  upon  spongy  platinum  contained  in  the  retort,  and  the 
platinum  be  heated  after  all  the  air  has  been  expelled,  it  will  become 
red-hot  and  produce  water  and  ammonia: 

N0«  +  5H  s=  NH'  +  2H0. 

(Hare,  J.  Pharm.  24, 146,)  (Vid.  Ammonia).  A  prepared  platinum  plate 
(II.,  47)  introduced  into  a  mixture  of  equal  measures  of  the  two  gases  at 
ordinary  temperatures  produces  no  condensation  in  the  course  of  one  hour; 
but  in  36  hours,  the  condensation  amounts  to  •}-  of  the  whole.  (Fa- 
raday, Poffg.  33,  1 49.)  A  mixture  of  spontaneously  inflammable  phos- 
phuretted  hydrogen  and  nitric  oxide  is  generally  decomposed  in  a  few 


NITRIC  OXIDE.  379 

honrs  at  ordinary  temperatures,  the  residne  consisting  of  nitrogen  and 
nitrous  oxide  gases.  (Dalton.)  The  mixture,  when  inflamed  hy  the 
electric  spark  or  by  the  admission  of  oxygen  gas,  explodes  with  a  bright 
light,  producing  water  and  phosphoric  acid  and  leaving  free  nitrogen. 
According  to  Thomson,  4  volumes  of  phosphnretted  hydrogen  gas  mixed 
with  excess  of  nitric  oxide,  decompose  12,  or  according  to  Dalton  14 
volumes  of  the  latter.  Now  if  4  volumes  of  phosphnretted  hydrogen 
gas  are  assumed  to  contain  1  volume  of  phosphorus  vapour  and  6 
volumes  of  hydrogen  gas,  they  will  together  require  5  +  3  =  8  volumes  of 
oxygen,  ana  will  consequently  decompose  16  volumes  of  nitric  oxide. 
Ammoniacal  ^as  may  also  be  exploded  with  nitric  oxide  by  the  electric 
spark;  according  to  Gay-Lussac,  a  mixture  of  the  two  gases  slowly  under- 
goes decomposition,  at  ordinary  temperatures.  [For  the  decomposition 
with  olefiant  gas,  see  the  latter.! 

6.  Charcoal  bums  more  brilliantly  in  nitric  oxide  gas  than  in  com- 
mon air.  Nitric  oxide  passed  over  charcoal  ignited  in  a  tube  is  resolved 
into  a  half-volume  of  nitrogen  gas  and  a  half-volume  of  carbonic  acid. 

S)alton.)  Pyrophori  take  fire  in  the  gas  and  burn  very  vividly.  (Sir  H. 
avy.)  According  to  W.  Henry,  a  mixture  of  carbonic  oxide  and  nitric 
oxide  gases — no  matter  in  what  proportions — cannot  be  inflamed  by  the 
electric  spark.  Phosphorus  burning  feebly  is  extinguished  by  nitric 
oxide ;  but  if  in  full  combustion,  it  continues  to  bum  in  the  gas,  almost 
with  as  much  splendour  as  in  oxygen,  producing  phosphoric  acid  and  free 
nitrogen.  Nitric  oxide  gas  in  which  bi-sulphide  of  carbon  is  difiiised, 
burns  with  a  brilliant  greenish  coloured  flame,  when  a  lighted  match  is 
applied  to  it.  (Berzelius.)  Burning  sulphur  is  extinguished  in  an  atmo- 
sphere of  nitric  oxide. 

7.  Heated  potassium  bums  vividly  in  nitric  oxide  gas :  if  the  po- 
tassium is  in  excess,  suboxide  of  potassium  and  nitrogen  gas  are  the 
results;  if  the  nitric  oxide  predominates,  peroxide  of  potassium  is  first 
formed,  and  is  afterwards  converted,  by  further  absorption  of  the  gas, 
into  nitrite  of  potash.  Sodium,  at  the  temperature  of  an  ordinary 
lamp,  has  no  action  on  nitric  oxide.  (Gay-Lussac  &  Th^nard.)  Red- 
hot  iron,  zinc,  arsenic,  and  sulphide  of  barium  absorb  oxygen  from 
nitric  oxide,  and  separate  half  a  volume  of  free  nitrogen.  (H.  Davy;  Gay- 
Lussao.) 

Comhinatwns.^^a.,  One  volume  of  water  absorbs  at  ordinary  temper- 
atures, according  to  Sir  H.  Davy,  -^',  according  to  W.  Henry,  .5*^;  and 
according  to  Dtuton,  -^  vol.  of  nitric  oxide  gas. 

h.  With  Sulphurous  acidi  c.  With  Sulphuric  acid.  d.  With  Flucride 
of  Boron,  e.  With  Fluoride  of  Silicium.  /.  With  Bichloride  of  Tin. 
g.  With  ferrous  salts  in  solution :  these  salts  absorb  the  gas  in  great 
abundance,  forming  a  dark  brown  liquid.  (See  also  Iron.)  Salts  of  stan- 
nous oxide  also,  according  to  Berzelius,  absorb  nitric  oxide  gas. 

IT  According  to  Reinsch  (J,  pr,  Chem,  28,  391;  also  BtuJin.  Repert. 
32,  164),  nitric  oxide  forms  with  several  acids  compounds  analogous  to 
that  which  it  forms  with  sulphuric  acid.  With  phosphoric  acid,  it  forms  a 
compound  which  crystallizes  in  fine  four-sided  prisms;  with  arsenic  acid,  a 
buttery  mass  which  is  decomposed  by  water;  these  compounds  are  obtained 
by  passing  the  gas  into  a  syrupy  solution  of  the  acid.  It  is  also  absorbed 
by  a  concentrated  solution  of  tartaric  acid.  The  crystallized  hydrate 
of  acetic  acid  forms  a  blue  compound  with  it.  When  nitric  oxide  is 
passed  into  a  bottle  containing  hydrochloric  acid  gas,  an  oily,  yellowish 


S80  NITROGEN. 

green  liauid  is  produced^  together  with  colourless  crystals^  which  are  in- 
stantly decomposed  with  enervescence  by  contact  with  water.  The  oily 
liquid  immediately  blackens  solution  of  green  vitriol.  Both  the  liquid 
and  the  crystals  decompose  spontaneously  after  keeping  for  some  dajs : 
chlorine  gas  is  one  of  the  products  of  the  decomposition.  IT 


C.    NiTEOUs  Acid.    NO*. 

ffyponitraus  acid,  Salpetrige  Saure,  Untersalpdrige  Saure,  Add^  pemir 
treux,  Actde  hyponitreux,  Acide  azoteux. 

Formation. — 1 .  By  the  decomposition  of  nitric  oxide  (p.  378). — 2.  When 
nitric  oxide  is  mixed  with  one-fourth  of  its  volume,  or  less,  of  oxygen 
gas.  One  volume  of  oxygen  gas  in  contact  with  solution  of  potash  and  a 
very  large  excess  of  nitno  oxide  gas,  condenses,  at  most,  4  volumes  of 
the  latter  and  produces  nitrite  of  potash.  (Gay-Lussac;  see  also  Thomson, 
Ann.  Phil.  17,  321.)— 3.  By  passing  nitric  oxide  gas  through  anhydrous 
hyponitric  acid  or  concentrated  nitric  acid  at  ordinary  temperatures : 

NO*  +  NO*  =  2N0»;  and  2N0«  +  N0»  =  3N0*. 
With  mercurous  oxide  also,  nitric  oxide  produces  mercurous  nitrite. 
(Peligot.) — 4.  When  hyponitric  acid  comes  in  contact  with  water  or 
salifiable  bases. — 5.  When  nitrate  of  lead  dissolved  in  water  is  boiled 
with  metallic  lead,  the  latter  is  oxidized  at  the  expense  of  the  nitric 
acid  and  produces  a  salt  of  nitrous  acid.  (Berzelius.) 

Preparation. — 1.  45  parts  (5  atoms)  of  water  are  gradually  poured 
through  a  glass  tube  drawn  out  to  a  fine  point,  into  92  parts  (2  atoms) 
of  hyponitric  acid  cooled  down  to  a  temperature  of  —  20°  (—4°  F.);  and 
the  two  green-coloured  strata  formed  {vid.  page  385)  are  heatea  in  a 
retort,  the  receiver  of  which  is  surrounded  by  a  freezing  mixture,  till 
the  boiling  point  rises  to  28®  (82*4°  F.).  A  distillate  is  obtained  of  an 
indigo-blue  colour.  (Fritzsohe.) — 2.  A  mixture  of  1  volume  of  oxygen 
gas  and  rather  more  than  4  volumes  of  nitric  oxide  gas,  is  first  pa^ed 
through  a  tube  filled  with  fragments  of  porcelain,  to  render  the  mixture 
more  complete,  and  then  into  a  curved  tube  cooled  down  to  —  20® ;  the 
acid  collects  in  the  lower  portion  of  the  latter  in  the  form  of  a  dark  green 
liquid.  (Dulong.) — 3.  Dry  nitric  oxide  gas  is  passed  through  anhydrous 
hyponitric  acid  contained  in  a  Liebig*s  potash-apparatus ;  a  green  liquid 
is  then  formed,  the  vapours  evolved  from  which  condense  in  a  glass  tube 
cooled  down  to  a  very  low  temperature,  and  form  a  bluish  green,  ex- 
tremely volatile  liquid,  which  may  be  regarded  as  a  mixture  of  nitrous 
and  hyponitric  acids.  (Peligot.) — 4.  One  part  of  starch  is  heated  with 
8  parts  of  nitric  acid  of  specific  gravity  1  "25 ;  and  the  gaseous  mixture 
disengaged  is  made  to  pass,  first  through  a  chloride  of  (»lcium  tube  two 
feet  in  length,  and  then  into  an  empty  glass  tube  cooled  down  to  —  20®, 
where  it  condenses  to  a  very  volatile  liquid,  which  is  colourless  when 
exposed  to  extreme  cold,  but  green  at  ordinary  temperatures.  (Liebig, 
Geigei*.  Handb.  d.  Pharm.  Anfi.  5,  219.)  By  the  partial  distillation  of 
the  liquid  obtaiued  by  Liebig's  method,  a  dark  green  acid  is  obtained, 
which  boils  at  -f-  10®,  but  contains  only  30*8  percent,  of  oxygen;  this 
liquid,  if  again  partially  distilled,  yields  an  acid  which  boils  at  —  2"^,  and 
contains  33  per  cent,  of  oxygen ;  it  is  therefore  still  mixed  with  hypo- 


NITROUS  ACID.  381 

nitric  acid.  (Peligot.)  The  green  colour  of  the  acid  prepared  by  the 
second,  third,  and  foarth  methods  indicates  the  presence  of  hyponitric 
acid;  probably  the  first  is  the  only  method  that  yields  a  pure  acicL 

Properties,  Nitrons  acid,  as  obtained  by  the  first  method,  is  a  deep 
indigo-blue  coloured,  highly  volatile  liquid,  boiling  below  zero,  probably 
even  below  —  10**.  (Fritzsche.)     Its  vapour  is  yellowish  red. 

Calculation.  Vol.  or:  Vol. 

N  14'  36*8  Nitrogen  gas     2  Nitric  oxide  gas 4 

30  24*  63*2  Oxygen  gas  3  Oxygen  gas    1 

n6=~..738^  100^0 

(N»03  =  2  :  88-52  +  3  .  100  =  47704.     Beraelius.) 

Decomposition,  The  acid  prepared  by  the  first  method  boils  below 
zero;  it  then  partly  distils  over  undecomposed,  and  is  partly  resolved 
into  nitric  oxide  gas  and  hyponitric  acid,  the  latter  remaining  in  the 
retort.  (Fritzsche.) 

2N03  =  N0«  +  NO^ 

The  nitrogen  appears  to  have  not  much  more  affinity  for  the  third  atom 
of  oxygen,  than  for  the  fourth,  and  for  the  latter  not  much  more  than  for 
the  fifth.  Very  trifling  circumstances  are  therefore  sufficient  to  alter  the 
composition  of  the  compounds  of  oxygen  and  nitrogen.  The  determi- 
ning cause  in  the  preceding  case  is  the  affinity  of  heat  for  the  nitric 
oxide,  or  the  elasticity  of  the  latter;  consequently  nitrous  acid  can  only 
exist,  under  the  ordinary  pressure  of  the  atmosphere,  at  temperatures 
many  degrees  below  0°. 

ComhinationB, — a.  With  water.  The  acid  prepared  by  the  first 
method  dissolves  in  water  at  0°  abundantly  and  without  decomposition, 
forming  a  light  blue-coloured  solution;  at  temperatures  above  0°,  how- 
ever, the  mixture  evolves  a  large  Quantity  of  nitric  oxide  gas  (Fritz- 
sche), leaving  a  solution  of  nitric  acid.  (Mitscherlich.) 
3N0^  +  n  Aq  =  2NO«  +  n  Aq,  N0«. 
In  this  case,  the  efiect  is  produced  b^  the  affinity  of  heat  for  nitric 
oxide,  and  that  of  water  for  nitric  acid.  The  aqueous  acid,  even  when 
largely  diluted,  turns  a  solution  of  ferrous  sulphate  brown,  by  imparting 
nitric  oxide  to  it. 

b.  With  sulphuric  acid? 

c.  With  salifiable  bases :  Salts  of  Nitrous  acid.  Nitrites,  Azoiites  (other- 
wise called  ^yponi^ri/e^).  1.  Nitric  oxide  gas  is  placed  in  contact  with 
solution  of  caustic  potash  (see  page  378). — 2.  A  mixture  of  1  volume  of 
oxygen  and  4  volumes  of  nitric  oxide  gas  is  passed  through  the  aqueous 
solution  of  an  alkali. — 3.  Liquid  or  gaseous  hyponitric  acid  is  brought  in 
contact  with  salifiable  bases  dissolved  or  difiused  in  water.  In  this  case, 
salts  of  nitrous  and  of  nitric  acid  are  formed  at  the  same  time ;  they  may, 
however,  be  separated  by  their  difierent  degrees  of  solubility  in  water. 

2KO  +  2NO*  =  KO,  N0»  +  KG,  NO». 

— 4.  Nitrate  of  potash  or  soda  is  heated  till  it  gives  up  2  atoms  of  oxygen, 

NaO,NO»  =  NaO,  N0>  +  20. 

Mitscherlich  (Lehrh.  1,  455)  fuses  nitrate  of  soda  in  an  earthen  crucible 
till  a  portion  dissolved  in  water  gives  a  brownish  instead  of  a  perfectly- 
white  precipitate^  with  nitrate  of  silver.      (The  white   precipitate  is 


882  NITROaSN. 

nitrite  of  silyer;  the  brownish  colour  prooeeda  from  a  portion  of  the 
already  produced  nitrite  of  soda  being  decomposed  and  conyerted  into 
caustic  soda,  which  precipitates  brown  oxide  of  silver  from  the  solution; 
(if  the  fusion  is  not  carried  thus  far,  a  large  quantity  of  nitrate  of  soda 
remains  undecomposed.)  He  then  dissolves  the  mass  of  salt  in  water; 
mixes  it  cold  with  nitrate  of  silver;  collects  the  precipitated  mixture  of 
nitrito  and  free  oxide  of  silver  on  a  filter ;  dissolves  out  the  former  by 
boiling  water;  and  sets  it  aside  to  crystallize.  To  obtain  other  nitrites 
from  this  salt,  Mitscherlich  decomposes  it  with  an  equivalent  quantity  of 
a  metallic  chloride, — ^for  example : 

AgO,  NO»  +  KCl  =  KO,  N0>  +  AgO. 
Fischer  {Pogg.  21,  160),  who  employs  nitrate  of  potash   proceeds  in  a 
manner  similar  to  the  above. — 5.  An  aqueous  solutiou  of  nitrate  of  lead 
is  boiled  with  metallic  lead.  (Berzelius.) 

The  salts  of  nitrous  acid  are  either  colourless  or  yellow,  and  for  the 
most  part  crystallizable.  The  alkaline  nitrites,  according  to  Fischer,  are 
neutral  to  vegetable  colours;  according  to  H.  Rose,  they  are  alkaline. 
They  also  fuse,  when  heated,  forming  a  yellowish  liquid  which  on  cooling 
solidifies  to  a  crystalline  mass.  When  strongly  heated,  these  salts  evolve 
their  acid  in  the  form  of  nitrogen  and  oxygen  gas.  The  aqueous  solution 
of  a  nitrite  is  decomposed  by  long  boiling  into  nitric  oxide  and  a  salt  of 
nitric  acid  with  excess  of  base.  (Berzelius.) 

3(K0,  NO^)  =  2KO  +  KO,  NO»  +  2N0«. 
The  nitrites  detonate  when  heated  with  combustible  bodies.  When 
treated  with  oil  of  vitriol  out  of  contact  of  air,  they  evolve  nitric  oxide 
gas,  while  the  liquid  takes  up  hyponitric  and  nitric  acids.  (Gay-Lussac.) 
If  air  be  admitted,  the  free  nitric  oxide  produces  red  fumes.  Weaker 
acids,  as  acetic  acid,  also  produce  the  same  reaction.  The  nitrites  preci- 
pitate the  metals  from  solutions  of  chloride  of  gold  and  nitrate  of  mercnrous 
oxide ;  from  salts  of  manganous  or  ferrous  oxide  they  throw  down  man- 
ganic or  ferric  oxide,  and  evolve  nitric  oxide  gas.  (Fischer.)  With  oil  of 
vitriol  to  which  a  solution  of  ferrous  sulphate  has  been  added,  they 
form  a  dark  red  liquid.  When  their  aqueous  solutions  are  boiled  in 
open  vessels,  they  readily  absorb  oxygen  and  are  converted  into  nitratee. 
(Berzelius.)  All  the  normal  salts  of  nitrous  acid  are  soluble  in  water, 
those  of  potash,  lime,  magnesia  and  protoxide  of  manganese  being  also 
deliquescent.  Most  of  the  other  nitrites  dissolve  readily,  with  the  excep- 
tion of  the  nitrite  of  silver,  which  is  but  difficultly  soluble;  consequently, 
the  other  salts,  when  not  too  largely  diluted,  give  a  white  precipitate  with 
nitrate  of  silver.  The  alkaline  nitrites  form  double  salts  with  the  nitrites 
of  lead,  cobalt,  nickel,  silver,  and  palladium.  (Fischer.) 

Deiman,  Hess,  and  R.  W.  Fischer  regard  the  above  salts  not  as 
salts  of  nitrous  acid  U.  g,  KO,  NO')  but  as  salts  of  nitric  oxide 
(KO,NO'). 

D.    Hyponitric  Acid.    NO*. 

Nitrous   Acid,    Salpetrige  Siiur^,   unvoUkommene  Salpeieriaure,  Acide 
nitreux,  Acide  hypoazotigue. 

Formation,— I,  When  oxygen  and  nitric  oxide  gases,  in  any  proportions 
whatever,  are  mixed  together  at  ordinary  temperatures,  and  in  the  absence 
of  water  and  salifiable  bases,  2  volumes  of  nitric  oxide  invariably  combine 


NITROUS  ACm.  S83 

with  1  Yolume  of  oxygen,  to  form  1  yolnme  of  hyponitric  acid  raponr. 
(Gay-Lnssao.) — 2«  Hypochlorons  acid  gas  explodes  with  nitric  oxide  gss 
at  ordinary  temperatures,  producing  hyponitric  acid  vapour  and  chlorine 
gas.  (Balard.) 

NO"  +  2C10  =  N04  +  2C1. 
— Euchlorine  gas  mixed  with  nitric  oxide  instantly  forms  red  fumes. 
(H.  Dayy.) — 3.  Chlorine  gas  in  the  dry  state  does  not  act  on  nitric 
oxide;  hut  if  water  is  present,  the  chlorine  takes  up  its  hydrogen, 
and  the  nitric  oxide,  comoining  with  the  oxygen  set  free,  is  converted 
into  hyponitric  acid. — 4.  Hyponitric  acid  is  produced  in  the  decompo- 
sition (1)  of  nitrous  oxide;  in  the  decomposition  (1)  of  nitric  oxide;  and 
in  the  decomposition  of  aqueous  nitric  acid  and  its  salts  hy  light,  elec- 
tricity, heat,  and  numerous  deoxidizing  suhstances,  and  especially  in  the 
transmission  of  nitric  oxide  gas  through  concentrated  nitric  acid. 

Preparation,^^!,    A  perfectly  dry  mixture   of  1  volume    of   oxy- 
gen gas  with  nearly  2  volumes  of  nitric  oxide  is  passed,  first  through 
a   tube  filled  with    pieces   of  porcelain,  and  then  through  a  curved 
tube   cooled  down  to  a   temperature    of   —20°,  where    the  hyponitric 
acid  vapour  condenses,  with  separation   of  a  small  quantity  of  oxy- 
gen, to   a  greenish  liquid  (containing  nitrous  acid?),   which    however 
turns  yellow  even  on  decantation.  (Dulong.)     The  gases  cannot  be  ren- 
dered perfectly  dry  by  chloride  of  calcium;   they  must,    therefore,  be 
passed  in  the  required  proportions,  first  over  oil  of  vitriol,  then  through 
a  tube  filled  with  fragments  of  recently  fused  hydrate  of  potatsh,  and  lastly 
into  a  long-necked  receiver  cooled  down  to  —  15°  or  —  20°.     If  by  this 
treatment  all  traces  of  water  have  been  completely  removed,  the  acid 
solidifies  in  colourless  crystals.     After  the  hydrate  of  potash  has  been 
used  for  some  time,  it  ceases  to  dry  the  gases  completely;  and  if  the 
process  is  continued,  the  crystals  deliquesce  and  form  a  green  liquid, 
which,  when  any  excess  of  oxygen  is  present,  becomes  continually  darker 
and  more  volatile.   (Peligot.)      [At    —  20°,   and   with   water  present, 
nitrous  acid  appears  to  be  the  principal  product  in  the  above  process,  and 
mixes  with  the  hyponitric  acid  in  constantly  increasing  quantities.]     To 
obtain  hyponitric  acid  in  the  form  of  vapour,  a  mixture  of  two  volumes 
of    nitric   oxide  with    one    volume    of  oxygen  is    passed    into  a  dry 
exhausted  glass  globe. — 2.  Perfectly  dry  nitrate  of  lead  is  heated  in  a 
retort  connected  with  a  cooled  receiver,  till  it  is  completely  decomposed, 
(Gay-Lussac.)     The  hyponitric  acid  collects  in  the  receiver,  while  the 
excess  of  oxygen  escapes  by  a  tube  fixed  into  the  tubulure.     According 
to  Dulong,  the  acid  thus  obtained  is  anhydrous,  or  contains  at  most  0*006 
water.     To  obtain  the  acid  by  this  process  perfectly  anhydrous  and  crys- 
tallized, the  nitrate  of  lead  is  dried  till  decomposition  commences,  and 
then  distilled  in  a  porcelain  retort,  the  distilled  product  passing  into 
a  receiver  which  is  kept  at   a   very  low    temperature   and   changed 
during  the   operation.     A  greenish  Lquid  containing  water  first  passes 
over,  then  a  colourless  liquid    containing  a  small  quantity  of  water, 
and  lastly  the  anhydrous  acid  which  solidifies  in  crystals.    (Peligot.) — 
3.  When  fuming  nitric  acid  is  gently  heated  in  a  retort  connected  with 
a  receiver  surrounded  with  a  freezing  mixture,  two  immiscible  strata  of 
liquid  collect  in  the  receiver.     The  lower  of  these  is  a  mixture  of  hypo- 
nitric acid  and  mono-hydrated  nitric  acid;   the  upper,  hyponitric  acid 
containing  a  small  quantity  of  mono-hydrated  nitric  acid.     On  distilling 
the  latter  at  a  gentle  heat,  the  hyponitric  acid  passes  over  in  a  state  of 
purity.  (Mitscherlich,  Lekrb,  I,  457.) 


384  NITROGEK. 

If  the  acid  is  required  in  crystals^  it  mnst  be  freed  by  partial  distil- 
lation from  the  nitric  acid  mixed  with  it,  [probably  formed  by  the  pre- 
sence of  a  trace  of  water,]  the  receiver  being  cooled  down  to  a  temperatore 
of  — 20^  (Fritzsche.) 

Properties,  Crystallizes  at  —20°  in  colourless  prisms  (Peligot, 
Fritzsche);  melts  at  —9^  (Peligot),  at  (+  or  —  ?)  13-5*  (Fritzsche). 
After  being  melted,  the  acid  does  not  again  solidify  at  — 16^  (Peligot), 
the  temperature  required  for  that  purpose  being  as  low  as  —30°,  because 
a  trace  of  nitric  acid  has  been  formed :  the  same  cause  also  gives  rise  to 
turbidity  during  the  cooling  of  the  liquid.  (Fritzsche.) — In  the  liquid 
state,  hyponitric  acid  has  a  specific  gravity  of  1'451  (Dulong);  at  a  tem- 
perature of  —20^  it  is  colourless;  at  —10°,  almost  colourless ;  between 
0°  and  H-10^  pale-yellow;  from  +15°  to  28°,  orange-yellow,  the  colour 
becoming  darker  as  the  temperature  rises.  (D along.)  At  22°  it  boils,  the 
thermometer  remaining  stationanr  (Peligot);  at  26°  (Gray-Lussac);  at  28°, 
with  the  barometer  at  0*76  met.  (Dulong.)  It  forms  a  dark  yellowish  red 
vapour  which  was  formerly  considered  as  a  permanent  gas,  because  when 
mixed  with  other  gases  it  is  not  condensed  by  exposure  to  cold.  It  has  a 
peculiar  sweetish  and  pungent  odour,  and  an  acid  taste.  Its  effects  when 
inhaled  are  most  injurious.  It  reddens  litmus,  and  stains  animal  matter 
yellow. 

Calculation.  Dulong.         Peligot. 

N     14-  30-44  29-96  30-57 

40     32-  69-56  7004  6943 

NO*  46-  100-00  10000  10000 

Vol.  Sp.  gr.  Or :  Vol.  Sp.  gr. 

Nitrogen  gaa  1  0*9706  Nitric  oxide  gas  2  2*0798 

Oxygen  gas    2  2-2186  Oxygen  gas 1  1-1093 

Hyponitric  acid  vapour   1  3-1892  1  3*1891 

(N«0»  +  N»0»  =  47704  +  67704  =  115208.    BerzeUus.) 
This  acid  is  regarded  by  Berzelius  as  a  compound  of  nitric  and  nitrous 
acid. 

Decompoiitions.  Hyponitric  acid  vapour  is  not  decomposed  at  a  mode- 
rate red  heat.  (Graham.) — 1.  The  vapour  mixed  with  excess  of  hydrogen 
gas  and  passed  over  spongy  platinum,  raises  the  latter  to  a  bright  red 
heat,  and  yields  water  and  ammonia.  (Kuhlmann.)  (See  also  Ammonia.) 
Ignited  charcoal  bums  in  hyponitric  acid  vapour  with  a  dull  red  flame. 
Phosphorus,  in  order  to  bum  it,  requires  to  be  heated  more  strongly 
than  for  oxygen  gas,  but  when  once  set  on  fire  burns  with  great  splen- 
dour. According  to  Dulong,  sulphur  when  strongly  heated  bums  in 
the  acid  vapour;  but,  according  to  others,  it  is  extinguished.  Iodine 
may  be  volatilized  in  hyponitric  acid  vapour  without  undergoing  oxida- 
tion. (Dulong.)  The  acid  has  scarcely  any  action  on  phosphuretted 
hydrogen  gas.  (Graham.) — 2.  Potassium  takes  fire  in  hyponitric  acid 
vapour  at  ordinary  temperatures,  and  burns  with  a  red  flame :  sodium 
also  decomposes  it,  but  without  disengagement  of  light  or  heat;  copper, 
tin,  and  mercury,  at  ordinary  temperatures,  slowly  decompose  the  vapour; 
if,  however,  the  vapour  is  passed  over  iron  or  copper  contained  in  a  tube  at 
a  red  heat,  nitrogen  gas  and  an  oxide  of  the  metal  are  obtained. — 3.  From 
an  aqueous  solution  of  hydrosulphuric  acid,  hyponitric  acid  rapidly  preci- 
pitates sulphur,  with  formation  of  ammonia ;  it  also  rapidly  decomposes  a 
solution  of  ammonia. 


HYPONiTRic  Acid.  383 

4.  Hjponitric  acid  is  decomposed  by  water,  and  cdnyerted,  by  iineq[ual 
distribation  of  its  oxygen,  into  nitric  acid,  on  the  one  band,  and  nitrous 
acid  and  nitric  oxide  on  the  other,— doubtless  because  the  water  has  little 
or  no  affinity  for  bjponitric  acid,  but  a  powerful  affinity  for  nitric  acid. 
The  decomposition  into  nitric  and  nitrous  acids  is  as  follows  : 

2N0^  =  N0»  +  N0»* 
The  decomposition  into  nitric  acid  and  nitric  oxide  is  : 
3N0«  =  2NO*  +  NO«. 

The  lower  tbe  temperature,  and  tbe  smaller  the  quantity  of  water  present, 
the  larger  is  the  proportion  of  nitrous  acid  and  the  smaller  that  of  the 
nitric  oxide.  But  the  nitrous  acid,  which  is  produced  in  preference  under 
these  circumstances,  may  be  afterwards  resolved  by  heat,  or  by  the  addi- 
tion of  bodies  which  promote  the  formation  of  gas  bubbles  (I.,  275,  3),  into 
nitric  acid  and  nitric  oxide : 

3N0»  =  NO»  +  2N0«. 
With  a  smaller  quantity  of  water,  a  portion  of  the  hyponitric  acid  remains 
undecomposed,  because  it  combines  with  the  nitric  acid  already  produced, 
and  appears  to  be  thereby  protected  from  the  further  decomposing  action 
of  the  small  quantity  of  water  present. 

When  a  small  quantity  of  water  is  added  to  a  large  excess  of  hypo- 
nitric  acid,  the  acid  acquires  a  deep  green  colour,  without  disengagement 
of  gas.  ^Dulong.)  According  to  Dulong,  the  green  colour  is  caused  by 
nitric  oxide  gas  formed  at  the  same  time  with  the  nitric  acid  and  remain- 
ing partially  dissolved ;  more  probably  however  by  the  nitrous  acid  pro- 
duced, as  this  compound  is  blue,  and  would  form  a  green  mixture  with 
the  undecomposed  hyponitric  acid. 

When  hyponitric  acid  is  added  in  separate  portions  to  a  given  quan- 
tity of  water,  the  first  portions  evolve  the  largest  quantity,  and  the  last 
not  even  a  trace  of  nitric  oxide  gas :  the  water  becomes  first  blue, 
then  green,  and  lastly  orange-yellow.  (Gay-Lussac.) — If  to  92  parts  (2 
atoms)  of  hyponitric  acid  cooled  down  to  — 20°,  9  parts  (I  atom)  of  water 
are  slowly  added  in  a  fine  stream,  a  small  quantity  only  of  nitric  oxide 
^as  is  evolved,  and  two  strata  of  liquid  are  formed,  the  upper  of  which  is 
dark  green,  and  the  lower,  amounting  to  a  third  of  the  whole,  of  a  grass- 
green  colour.  The  upper  stratum  begins  to  boil  at  -\-  20° ;  but  its  boiling 
point  quickly  rises  to  120°,  a  blue  liquid  at  the  same  time  distilling 
over  in  small  quantity  into  the  receiver,  which  must  be  surrounded  with 
a  freezing  mixture.  [This  liquid  is  probably  a  mixture  of  a  large  excess 
of  hydratcd  nitric  acid  with  hyponitric  and  nitrous  acids.]  The  boiling 
point  of  the  lower  stratum  ascends  gradually  from  + 17°  to  28°,  at  which 
latter  point  it  remains  constant,  and  a  greenish  blue  liquid  distils  over 
(nitric  acid  with  a  small  quantity  of  hyponitric),  leaving  yellow  hypo- 
nitrous  acid  in  the  retort. — If  in  the  same  manner,  45  parts  (5  atoms)  of 
water  are  added  to  92  parts  (2  atoms)  of  hyponitric  acid,  in  which  case 
the  decomposition  may  take  place  as  follows  : 

2N0*  +  5Aq  ^  NO»,  5Aq  +  NOS 

very  little  nitric  oxide  gas  is  disengaged  and  two  similar  strata  of  liquid 
are  obtained.  The  upper  stratum  behaves  as  in  the  first  experiment;  tbe 
lower  however,  from  its  exceedingly  deep  bluish  green  colour,  appears 
transparent  only  when  in  thin  layers,  and  enters  into  violent  ebullition  even 
on  being  poured  out  from  the  vessel.  When  both  liquids  are  distilled  toge- 
ther, the  lower  stratum  begins  to  boil  even  below  0°;  and  by  the  time 

VOL.   II.  2  c 


380  KITROOEN. 

that  tbe  boiling  point  has  risen  to  25°.  it  is  wholly  carried  over  into  the 
receiyer  (which  is  surrounded  with  a  freezing  mixture)  in  the  form  of  a 
blue  distillate  of  nitrous  acid.  (Fritzsche.) 

When  hyponitric  acid  is  mixed  with  5  times  its  volume  o  water  at 
ordinary  temperatures,  a  large  quantity  of  nitric  oxide  gas  is  evolyed. 
When  this  action  ceases,  the  immersion  of  a  platinum  wire  gives  rise  to 
further  disengagement  of  gas;  and  if  heat  be  applied,  the  action  becomes 
so  violent  that  the  liquid  is  scattered  about.  A  still  more  violent  and 
prolonged  evolution  of  gas  than  that  caused  by  platinum,  is  produced  by 
metals  which  are  attacked  by  the  acid,  such  as  iron,  copper,  brass,  and 
silver.  The  action  on  the  metals  is  very  slight;  but  the  small  bubbles  of 
nitric  oxide  gas  which  are  formed  by  their  oxidation,  cause  the  nitrous 
acid  present  likewise  to  give  off  nitric  oxide  gas.  Wood-shavings  also 
cause  effervescence  on  account  of  the  air  which  adheres  to  them ;  but  if 
previously  boiled  in  water,  they  scarcely  produce  any  effect.  On  mixing 
one  measure  of  hjrponl trie  acid  with  10  measures  of  water,  nitric  oxide  gas 
is  likewise  disengaged.  The  colourless  liquid  yields,  when  boiled,  an 
additional  60  measures  of  nitric  oxide  gas ;  out  the  evolution  of  gas  con- 
tinues for  the  space  of  an  hour :  if  platinum  wire  be  present,  it  ceases 
much  sooner.  In  this  mixture,  also,  the  above  mentioned  oxidable  metals 
produce  violent  effervescence,  whereas  they  are  but  feebly  attacked  by  a 
mixture  of  one  measure  of  nitric  acid  and  10  measures  of  water.  If  one 
measure  of  hyponitric  acid  is  added  by  drops  to  25  measures  of  boiling 
water,  the  whole  of  the  nitric  oxide  is  not  immediately  evolved;  for  it  is 
only  after  long  boiling  that  the  liquid  ceases  to  give  a  brown  colour 
with  solution  of  green  vitriol.  A  mixture  of  hyponitric  acid  with  an 
excess  of  concentrated  nitric  acid  does  not  evolve  gas  when  mixed  with 
water.  (Schonbein.) 

5.  The  alkalis  act  in  a  similar  manner  to  water,  inasmuch  as  they 
also  possess  little  or  no  affinity  for  hyponitric,  but  a  very  powerful 
affinity  for  nitric  acid.  A  concentrated  solution  of  potash  yields  with 
hyponitric  acid,  nitrite  and  nitrate  of  potassa,  with  slight  evolution  of 
nitric  oxide  gas.  (Gay-Lnssac,  Dulong.)  Hyponitric  acid  vapour  tnui^- 
mitted  at  ordinary  temperatures  over  pure  baryta,  is  slowly  absorbed; 
at  200°,  the  baryta  suddenly  becomes  red-hot,  fuses,  and  is  converted, 
without  disengagement  of  gas,  into  nitrate  and  nitrite  of  baryta. 
(Dulong.) 

Combinations,     a.  With  Aoueous  Nitric  acid. 
b.  With  Salifiable  Bases.     The  only  compound  known  is  that  with 
oxide  of  lead. 


B.    Nitric  Acid.    NO*. 

Salpetersaiire,  Perfect  Nitric  Add-,  Adde  nitriqtte,  Aeide  aasotique,  Addum 

nitricum. 

Sources,  In  combination  with  potassa,  soda,  lime,  and  magnesia  on 
the  surface  of  the  earth  where  organic  matter  has  undergone  decomposi- 
tion; in  numerous  springs,  in  many  plants  which  absorb  the  nitrates 
from  the  soil  where  they  are  produced  (see  Vaudin,  J.  Chim.  Med.  8, 
674;  9,321);  in  rain-water  after  a  thundeivstorm.  (Liebig.) 


NITBIO  ACID.  «6f 

Fomuctum.'^l*  From  Nitrogen  and  Oxygen :— -o.  When  a  mixture 
of  3  volumes  of  nitrogen  gas  and  7  volumes  of  oxygen  (or  more  accu- 
rately, 2  nitrogen  and  5  oxygen)  is  placed  over  water  or  an  aqueous 
solution  of  potash,  and  electric  sparks  passed  throuffh  it  for  a  week, 
condensation  takes  place,  and  nitric  acid  is  formed!  (Cavendish.)— 6. 
Platinum  wire  heated  by  the  electric  current  in  a  mixture  of  nitrogen 
gas,  oxygen  gas,  and  aqueous  vapour,  till  it  fuses,  gives  rise  to  the  pro- 
duction of  nitric  acid.  (H.  Dairy.) — c.  When  a  mixture  of  1  volume 
of  nitrogen  with  14  of  hydrogen  is  burned  in  oxygen  gas,  nitric  acid  is 
formed.  (Berzelius.) — d.  Aqueous  vapour  (mixed  with  air?)  passed  over 
ignited  peroxide  of  manganese,  yields  nitric  acid.  (H.  Davy.) — e.  When 
water  containing  atmospheric  air  is  decomposed  by  a  current  of  electri* 
city,  traces  of  nitric  acid  are  formed  at  the  positive  pole.  (H.  Davy.) — 
A  mixture  of  nitrogen  and  oxygen  gases  passed  through  a  red-hot  tube, 
does  not  yield  nitric  acid;  not  even  when  the  tube  contains  spongy 
platinum  or  platinum  black;  neither  is  nitric  acid  formed  by  passing 
nitrogen  gas  either  dry  or  moist,  over  ignited  peroxide  of  man- 
ganese. (Kuhlmann.)  A  mixture  of  2  volumes  of  nitrogen  gas  and  5 
of  oxygen  likewise  remains  unaltered  when  enclosed  in  a  tube  by 
means  of  solution  of  potash  and  mercury,  and  immersed  in  the  sea  to 
the  depth  of  540  metres  (or  295  fathoms)  though  it  must  then  sustain 
a  pressure  of  50  atmospheres.  (Laroche,  Sckw.  1,  123  &  172.) 

2.  From  Nitrous  Oxide,  by  its  decomposition  in  contact  with  water, 
(p.375,  1.) 

3.  From  Nitric  Oxide,  a.  By  its  decomposition  in  contact  with 
water,  (p.  378,  1.) — b.  Even  with  excess  of  oxygen,  nitric  oxide  forms 
nitric  and  not  hjponitric  acid,  only  when  water  or  a  salifiable  base  is 
present.  If  nitric  oxide  is  passed  into  oxygen  gas  confined  in  a  vessel 
by  water  at  a  temperature  of  52^,  the  formation  of  nitric  acid  ensues^ 
attended  with  a  slight  explosion.  (Lampadius,  J.  pr,  Chem,  4,  391.)—- 
c.  With  aqueous  solution  of  hypochlorous  acid,  nitric  oxide  gas  yields 
nitric  acid  and  chlorine;  it  acts  in  a  similar  manner  with  the  hypochlo- 
rites. (Balard.) 

4.  From  Nitrous  Acid,  by  its  decomposition  in  contact  with  water 
(see  page  381). 

5.  From  Hyponitric  Acid. — a.  In  the  decomposition  of  that  substance 
(4  and  5,  pp.  885,  386). — 6.  Hyponitric  acid  is  converted  into  nitric 
acid,  when  mixed  with  water  and  oxygen  gas  or  with  aqueous  iodic 
acid,  iodine  being  set  free  in  the  latter  case  (Gaultier  de  Claubry);  or 
with  hydrated  hypochlorous  acid,  the  decomposition  being  attended  with 
separation  of  free  chlorine.  (Balard.) 

6.  From  Ammonia. — a.  When  a  mixture  of  ammoniacal  gas  with 
excess  of  oxygen  is  transmitted  through  a  red-hot  tube,  explosion  takes 
place  and  nitnc  acid  is  produced.  (Fourcroy.)  A  mixture  of  ammoniacal 
gas  and  atmospheric  air  passed  through  a  red-hot  glass  tube,  yields  a 
small  quantity  of  nitric  oxide  and  hyponitric  acid;  spongy  platinum 
introduced  into  the  tube  produces  no  effect  at  ordinary  temperatures; 
but  if  heated  to  308°  in  a  current  of  the  mixture,  it  becomes  red- 
bot,  and  gives  rise  to  the  formation  of  nitric  and  hyponitric  acids,  or  if 
very  strongly  heated,  of  the  latter  only;  when  the  ammonia  is  in  excess, 
nitrate  of  ammonia  is  produced.  A  mixture  of  the  vapour  of  carbonate 
of  ammonia  with  atmospheric  air  yields  less  nitric  acid  than  that  of  pure 
ammonia  with  air;  sal-ammoniac  vapour  with  atmospheric  air  yields 
chlorine,  hyponitric  acid,  and  water.  (Kuhlmann.) — 6.  Ammoniacal  gas 

2  0  2 


S88  '  KITROGBN. 

passed  over  peroxide  of  manganese  ignited  in  a  gnn-barrel,  yields  nitric 
oxide  gas  (Milner,  Crell,  ilnn.  1795,  1,  554);  bat  if  tbe  peroxide  of 
manganese  is  ignited  in  a  porcelain  tube,  nitrate  of  ammonia  is  obtained. 
(Morveau,  Schw,  J,  9,  370;  Vauquelin,  J.  Polytetkn,  Cah,  2,  174.)  Am- 
moniacal  gas  passed  orer  ignited  sesqui-oxide  of  iron  also  yields  a 
large  quantity  of  nitrate  of  ammonia.  (Liebig,  Mag,  Fharm.  33,  40.)-^ 
c.  A  mixture  of  milk  of  lime  with  a  small  quantity  of  ammonia  enclosed 
for  six  weeks  in  summer  in  a  stoppered  bottle  containing  air  and  fre« 
quently  shaken,  produces  nitric  acid.  (Collard  de  Martigny,  J.  Ckim, 
Med.,  3,  525;  see  also  Kublmann,  N.  Ann.  Chem.  Pkys.  20,  223.) 

7.  From  organic  substances  containing  nitrogen. — a.  Cyanogen  gas 
mixed  with  atmospheric  air  and  passed  through  a  red-hot  glass  tube  con- 
taining spongy  platinum,  yields  byponitric  acidaud  carbonic  acid.  (Kuhl- 
mann. — 6.  Azotized  organic  matters  exposed  to  the  air  in  contact  with 
salifiable  bases  and  water,  yield  salts  of  nitric  acid.  The  bajse  may  even 
be  ammonia,  produced  in  the  decomposition  of  the  organic  compound. 
The  predisposing  affinity  of  the  base  for  nitric  acid  causes  the  nitro- 
gen— at  the  moment  when  it  is  set  free  by  the  decomposition  of  tlie  organic 
matter,  and  before  it  has  assumed  the  gaseous  form,  that  is  to  say,  while 
it  is  in  the  ncueent  state  (I,  37,  38) — to  unite  with  the  oxygen  of  the  air, 
and  form  nitric  lEusid. — Kuhlmann  supposes  that,  in  the  formation  of  nitric 
acid,  when  the  mixture  contains  no  carbonate  of  potassa,  but  only  car^ 
bonate  of  lime  and  carbonate  of  magnesia^  ammonia  is  first  formed  from 
the  nitrogen  disengaged  by  the  decomposing  organic  matter;  that  the 
ammonia  produces  nitrate  of  ammonia  by  takmg  up  oxygen  from  tbe  air; 
and  that  the  latter  salt  then  undergoes  double  decomposition  with  the 
carbonates  of  lime  and  magnesia,  giving  rise  to  nitrate  of  lime  and  mag- 
nesia and  carbonate  of  ammonia.  According  to  this  theory,  the  ammo- 
nia is  at  the  same  time  the  source  of  the  nitric  acid^  and  the  vehicle  of 
its  transference  to  the  fixed  salifiable  bases.  In  crude  saltpetre-ley, 
Kuhlmann  always  detected  ammonia,  partly  combined  with  carbonic 
acid  and  partly  with  fixed  acids.  The  observation  of  Collard  de 
Martigny  above  referred  to  also  corresponds  with  this  view. — Dried 
plants  and  their  extracts,  exposed  for  months  or  years  to  the  influ- 
ence of  moist  air,  become  much  richer  in  nitrates  than  in  the  fresh 
state,  in  consequence  of  the  gradual  decomposition  of  the  nitrogenous 
compounds  which  they  contain;  and  the  solution  obtained  by  exhaust- 
ing them  with  water,  frequently  evolves  nitric  oxide  gas  when  boiled, 
(Braconnot,  Ann.  Ckim.  Phys.  35,  261;  also  Fogg.  10,506;  Planche- 
J.  Pkarm.  23,  548;  Vaudin,  J.  Chim.  Med.  8,  674;  9,  321.)  Accord- 
ing to  Saussure  (BibL  Univ.  56,  130),  the  nitrogen  of  the  air  is  like^ 
teise  concerned,  in  this  case,  in  the  formation  of  nitric  acid.  Long- 
champ  {Ann.  Chim.  Phys.  33,  5;  34,  215)  is  of  opinion  that  oigamo 
azotized  compounds  have  nothing  to  do  with  the  formation  of  nitre, 
but  that  the  water  contained  in  porous  bodies,  such  as  chalk,  absorbs 
oxygen  and  nitrogen  from  the  air  and  condenses  them  in  the  form  of 
nitric  acid.  The  observation  of  Gaultier  de  Claubry  (Ann.  Chim.  Phys. 
52,  24),  that  a  very  large  quantity  of  nitrates  is  produced  in  chalk  hills, 
which  contain  but  a  trace  of  organic  matter,  is  in  favour  of  this  yiew« 
It  may,  however,  be  admitted  tliat,  under  certain  circumstances,  namely, 
during  electric  disturbances  in  the  air  (vid.  Atmospheric  air),  the 
nitrogen,  the  nitric  acid,  and  the  carbonate  of  ammonia  contained 
in  the  atmosphere  may  assist  in  the  formation  of  nitre — without  at  the 
same  time  denying,  that  the  nitrogen  contained  in  organic  matter  plays 


NITRIC  ACID.  389 

by  far  the  most  important  part  in  the  ordinary  production  of  nitre. 
(Gay-Lussac,  Ann.  Ckim.  Phys.  34,  5^-,  see  also  Fontenelle,  J,  Pharm. 
10,  14.) 

IT  Preparation.     By  treating  perfectly  dry  nitrate  of  silver  with  per- 
fectly dry  chlorine,  and  condensing  the  liberated  acid  vapour  by  a  freezing 
mixture.     The  nitrate  of  silver  is  placed  in  a  U-tube  capable  of  containing 
about  500  grammes  (15  or  16  oz.)  of  the  salt.    This  tube  is  connected  with 
another  U-tube  of  considerable  size,  and  having  at  the  bottom  a  small  sphe- 
rical reservoir,  which  serves  to  receive  a  very  volatile  liquid  (nitrous  acid?), 
produced  in  the  course  of  the   operation.       The  tube  containing  the 
nitrate  of  silver  is  immersed  in  water  covered  with  a  thin  layer  of  oil 
and  heated  by  means  of  a  spirit  lamp,  which  communicates  with  a  reser- 
voir kept  at  a  constant  level.     The  chlorine  is  evolved  from  a  glass  gaso- 
meter, and  its  displacement  is  regulated  by  a  slow  and  constant  flow  of 
sulphuric  acid;  it  is  dried  by  passing  over  chloride  of  calcium  and  then 
over  pumice-stone  moistened  with  sulphuric  acid.     The  bend  of  the  large 
U-tube  is  immersed  in  a  freezing  mixture.     The  nitrate  of  silver  is  first 
heated  to  180"*  (356''  F.^  and  deprived  of  moisture  by  passing  a  cur- 
rent of  dry  carbonic  acid  gas  through  the  apparatus.     After  this,  the 
transmission  of  the  chlorine  is  commenced.     At  ordinary  temperatures  it 
appears  to  exert  no  action;  but  when  the  nitrate  of  silver  is  heated  to  95* 
(203"  F.),  and  the  temperature  then  lowered  to  58'— 68*  (136°— 154°  F.), 
the  decomposition  of  the  nitrate  takes  place,  chloride  of  silver  being 
formed,  and  nitric  acid  and  oxygen  evolved.     At  first  a  portion  of  hypo- 
nitric  acid  is  developed,  but  as  soon  as  the  temperature  has  reached  its 
lowest  point,  crystals  of  anhydrous  nitric   acid  are  formed  and  soon 
obstruct  the  U-tube.     The  temperature  produced  by  the  use  of  ice  alone 
is  low  enough  for  the  production  of  these  crystals.     The  gases  evolved 
during  the  process  are  coloured;  and  in  the  spherical  reservoir  at  the  bot- 
tom of  the  tube,  there  collects  a  small  quantity  of  liquid  which  must  be 
removed  from  the  apparatus  before  transferring  the  nitric  acid  to  another 
vessel.    To  efiect  this  transference,  the  current  of  chlorine  must  be  replaced 
by  a  current  of  carbonic  acid;  the  condensing  tube  must  no  longer  be 
cooled;  and  the  bulb  destined  to  receive  the  crystals  must  be  immersed  in 
a  freezing^  mixture  and  connected  with  the  U-tube  by  means  of  a  caout- 
chouc tube  lined  with  asbestos.     The  chlorine  should  pass  very  slowly, 
not  more  than  3  or  4  litres  (about  60  cub.  in.)  in  24  hours.     An  appa- 
ratus arranged  as  above  described  will  go  on  day  and   night  without 
superintendence:  it  is  merely  necessary  to  renew  the  supply  of  sulphuric 
acid  which  displaces  the  chlorine,  the  alcohol  which  feeas  the  lamp,  and 
the  freezing  mixture.  (Deville;  vid.  Chem.  Gaz.  Apr.  2,  1849.) 

Properties.  Anhydrous  nitric  acid  forms  transparent  colourless  crys- 
tals of  great  brilliancy,  having  the  form  of  prisms  with  six  faces  and  appa- 
rently derived  from  a  right  rhombic  prism.  When  slowly  deposited 
in  a  current  of  the  gas  strongly  cooled,  they  attain  a  considerable  size. 
They  melt  a  little  above  30°  (85*  F.),  and  boil  at  about  45*  (113*  F.). 
At  10*  (50°  F.)  the  tension  of  the  vapour  is  very  considerable.  At  tem- 
peratures near  the  boiling  point,  decomposition  appears  to  begin:  hence 
the  tension  of  the  vapour  cannot  be  determined  by  Dumas'  process. 
(Deville.)    IT 


890  NITROGEN. 

Caloulation.  LsToirier.    CaTeadish.  Beneliiis.     Dtnj. 

N    14  25-9  20    25  26    29-5 

60    40  741  80    75  74    70*5 

NO»   54  100-0  100    100  100  1000 

Vol.  Or,  Vol. 

Nitrogen  gas  8  Nitric  oxide  gas  4 

Oxygen  gaa    5  Oxygen  gas  8 

(N«0»  =  2  .  88-52  +  500  =  67704.    BerzeUua.) 

C<mtnnations,  a.  AqaeooB  Nitric  acid.  In  the  concentrated  state: 
S^rU  of  Nitre,  Salpetergeist,  Spiritui  nUri  acidu$;  in  the  dilate  state: 
A^[uafarti$,  doppelUs  und  ein/aches  Seheidewaater. 

IT  FamuUian.  By  dissolving  anhydrons  nitric  acid  in  water.  The 
crystals  diasolre  completelyi  causing  great  rise  of  temperature,  but  no 
disengagement  of  gas  or  production  of  colour.  The  solution  saturated 
with  bar3rta  and  eyaporated^  yields  ciystaU  of  nitrate  of  baryta.  IT. 

Preparation. — 1.  From  Nitrate  of  Potash.  100  parts  of  purified  salt* 
petre  are  distilled  in  a  glass  retort  with  96  parts  of  common  oil  of  yitriol, 
till  the  residue  in  the  retort  becomes  tranquil,  and  no  more  drops  distil 
oyer.  The  receiyer,  which  is  cooled  with  water  and  not  attached  to  the 
retort  by  any  cement,  is  changed  as  soon  as  the  acid  which  passes  oyer 
ceases  to  ffiye  a  cloud  with  nitrate  of  silyer.  The  first  receiyer  contuns 
nitric  acid  contaminated  with  chlorine ;  the  second,  nitric  acid  in  a  state 
of  purity. 

The  ingredients  should  be  but  little  more  than  sufficient  to  half  fill 
the  retort,  or  there  will  be  danger  of  the  mixture  boiling  over.  When  a 
tubulated  retort  is  employed,  the  oil  of  yitriol  is  introduced  through  the 
tubulus;  but  with  a  plain  retort,  the  acid  is  poured  down  the  neck  by 
means  of  a  bent  tub&>fannel,  care  being  taken  not  to  soil  the  neck 
with  the  oil  of  yitrioL  The  neck  of  the  retort  must  reach  almost 
to  the  middle  of  the  receiver,  and  must  be  attached  to  it  without  any 
eement.  The  receiver  must  be  surrounded  with  cold  water,  or,  together 
with  the  neck  of  the  retort,  enveloped  in  bibulous  paper  kept  constantly 
wet  by  a  stream  of  water  from  a  dropping  bottle.  {App,  36.) 

Nitre,  even  when  purified,  contains  chloride  of  potassium  or  sodium, 
which  at  the  commencement  of  the  process  gives  rise  to  the  evolution  of 
a  yellowish-red  mixture  of  hyponitric  acid  vapour  and  chlorine  gas. 
KO,  N0»  +  Naa  +  2S0»  «  KO,  SO*  +  NaO,  S0»  +  NO*  +  Ci. 
As  the  whole  of  the  chlorine  passes  over  at  the  beginning  of  the  distil- 
lation, an  acid  is  at  length  obtained  perfectly  free  from  chlorine ;  tJiis 
pure  acid  amounts  to  one-half  or  two-thirds  of  the  whole.  It  is  well  to 
change  the  receiver  as  soon  as  the  acid  drops  which  fall  from  the  neck  of 
the  retort,  produce  but  a  slight  turbidity  in  a  solution  of  nitrate  of  silver, 
and  again,  when  they  cease  to  cause  any  turbidity  whatever.  If  the  nitre 
be  purified  by  repeated  crystallization  (according  to  the  method  described 
in  paffe  15,  vol.  I.)  from  every  trace  of  chloride,  it  yields  a  perfectly  pure 
acid  from  the  commencement. 

For  every  atom  of  nitre  (  =  101*2  parts)  2  atoms  of  oil  of  vitriol 
(  =  98  parts)  are  re(juired;  in  which  case,  1  atom  of  water  passes  over 
with  1  atom  of  nitric  acid,  and  bisulphate  of  potassa  with  1  atom  of 
water  remains  in  the  retort. 

KO,NO«  +  2(HO,  SO')  =  K0,H0,2S0»  +  HO,NO». 


NITRIC  AGID.  391 

As  101*2  parts  (1  atom)  of  nitre  contain  54  parts  (1  atom)  of  nitric 
acid^  and  the  latter  combines  with  9  parts  (1  atom)  of  water,  100  parts 
of  nitre  should  3deld  62*25  parts  of  acid.     But  in  reality  a  larger  quan- 
tity is  obtained;  because,  according  to  Hess  {Pogg,  53,  537),  the  mo- 
nohjdrated   acid  (HO,  NO*)    distils   over  at  the  commencement  only, 
and  afterwards    the  bihjdrated  acid   (2 HO,  NO*),   the  bisulphate  of 
potassa,   when  strongly  heated,    giving  up  part  of  its  water  to  the 
nitric  acid.      Accordingly,  Bucholz  {TascfCmh,  1819,  201)  who,  follow- 
ing SUersen's  directions,  distilled  100  parts  of  nitre  with  95  parts  of  oil 
of  vitriol,  obtained  65-6  parts  of  nitric  acid.   Geiger  {N.  Tr.  3,  1,  456), 
obtained  from  100  parts  of  nitre  and  95*83  parts  of  oil  of  vitriol,  68*75 
parts  of  nitric  acid  and  126*04  parts  of  residue.    R.  Phillips  {Ann.  FkiL 
30,  429;  9^bo  Kastn.  Arch.  13,  198},  obtained  from  100  parts  of  nitre 
and  100  parts  of  sulphuric  acid  of  1  -844  specific  gravity,  65*9  parts  of 
an  acid  of  1*5035  specific  gravity,  which  for  every  54  parts   (1   atom) 
of  anhydrous  acid,   contained  13*5  parts  (1^  atoms)  of  water — and  a 
residue  of  bisulphate  of  potash,  amounting  to  198*6  parts.  (Loss  =  1*4 
parts.) — Mitscherlich  {Pogg*  18,  152)  also  found  the  proportion  of  98*6 
parts  of  oil  of  vitriol  to  100  parts  of  nitre,  the  most  suitable.     The 
mixture  becomes  pasty  when  heated,  and  at  a  temperature  of  1 20^  to 
125",  (248^—257''  F.),  readily  gives  off  nitric  acid  of  specific  gravity 
1*522,  at  12*5°  (54*5°  F.).— More  than  2  atoms  of  oil  of  vitriol  to  1  atom 
of  nitre,  does  not  &ci1itate  the  disengagement  of  the  nitric  acid,  and 
towards  the  end  of  the  distillation,  may  cause  the  latter  to  be  contami- 
nated with  sulphuric  acid.     If  1   atom   of  nitre  be  distilled — as  was 
formerly  the  practice— with   only  1  atom  of  oil  of  vitriol  (100  parts 
to  48  parts),  the  first  half  of  the  nitric  acid  is  disengaged  with  facility, 
since  the  sulphuric  acid  decomposes  half  of  the  nitre  as  above, 

2(KO,NO»)  +  2HO,S03  ==  KO,  NO»  +  KO,  HO,  2SO»  +  HO,  N0»; 
but  the  bisulphate  of  potassa  thus  produced,  decomposes  the  rest  of  the 
nitre,  at  a  temperature,  which,  according  to  Mitscherlich,  is  not  below 
220°  (428°  F.) ;  and  at  that  degree  of  heat,  a  great  portion  of  the  acid 
evolved,  is  resolved  into  hyponitric  acid  vapour  and  oxygen  gas,  so  that 
the  acid  first  distilled  over  is  converted,  by  absorption  of  hyponitric  acid, 
into  red  fuming  nitric  acid. 

Diluting  the  oil  of  vitriol  with  water  has  no  other  effect  than  to 
render  necessary  the  employment  of  more  fuel  and  condensing  water, 
and  increase  the  difficulty  of  getting  rid  of  the  chlorine.  Mitscherlich 
recommends  for  100  parts  of  nitre,  a  mixture  of  96*8  parts  of  oil  of 
vitriol  and  40*45  parts  of  water;  the  mixture  becomes  liquid,  distils 
tranquilly  at  a  temperature  of  130^  to  132°,  and  yields  throughout  the 
process  an  acid  of  specific  gravity  1  '40.  By  using  fuming  oil  of  vitriol, 
a  portion  of  the  nitric  acid  is  resolved,  from  deficiency  of  water,  into 
hyponitric  acid  and  oxygen  gas.  Any  arsenious  acid  which  may  be 
contained  in  the  oil  of  vitriol,  remains  behind  in  the  residue,  without 
contaminating  the  nitric  acid. 

2.  From  commercial  Nitrate  of  Soda — Chili  saltpetre.  100  parts  (1 
atom)  of  nitrate  of  soda  are  distilled  in  the  same  manner  as  above,  with 
58  parts  ^1  atom)  of  oil  of  vitriol. — With  soda-nitre,  2  atoms  of  sul- 
phuric acid  are  not  required;  the  decomposition  takes  place  at  a  lower 
temperature,  and  the  acid  obtained  is  of  a  pale  yellow  colour.  (Graham, 
Lehrb.  2,  69.^  If  two  atoms  of  oil  of  vitriol  are  employed,  the  acid  must 
be  diluted  with  one-fourth  its  weight  of  water,  to  prevent  the  mass  from 
boiling"  over ;  the  best  proportions  are,  100  parts  of  nitrate  of  soda,  1 16*7 


392  miROGEN. 

parts  of  oil  of  Titriol  and  30  parte  of  water;  for  tbe  bisnlphate  of  sodft 
retains  not  only  1  atom  of  water,  like  the  potash-salt,  but  3  atoms, 
which  it  tends  to  separate  from  the  nitric  acid,  so  that  the  mass  becomes 
solid,  and  the  acid  is  partly  resolved  into  hyponitric  acid  and  oxygen 
gas.  (Wittstein,  Repert,  64,  289.) 

On  the  large  scale,  the  potash  or  soda  nitre  is  distilled  in  horizontal 
cast  iron  cylinders,  or  similar  vessels.  Formerly,  calcined  green  vitriol 
or  moistened  clay  was  substituted  for  sulphuric  acid  in  this  process; 
the  greater  part  of  the  acid  then  distilled  over  as  hyponitric  acid,  which, 
when  condensed  by  the  water,  yielded  aqxia  foriu  {ScheideuKMer.}— The 
ordinary  acid  may  be  purified  by  distillation  with  a  small  quantity  of 
nitre — ^the  receiver  being  changed  in  the  course  of  the  process.  Acid 
containing  chlorine  passes  over  first,  and  afterwards  pure  nitric  acid. 

Or,  in  order  to  obtain  an  acid  as  concentrated  and  as  free  as  possible 
from  chlorine  and  hyponitric  acid,  Millon  distils  it  till  a  third  part  has 
passed  over,  and  then  distils  the  rest  with  an  eoual  measure  of  oil  of  vitriol, 
the  receiver  being  changed.  The  latter  distillate  he  purifies  by  a  second 
distillation  from  the  sulphuric  acid  which  comes  over;  heats  the  distillate 
to  the  boiling  point  in  the  bottle  in  which  he  intends  to  preserve  it;  and 
passes  a  continuous  current  of  carbonic  acid  gas  through  it,  till  the 
acid  becomes  cold.  Should  the  specific  gravity  of  the  acid  exceed  1-5, 
the  heating  and  current  of  carbonic  acid  gas  must  be  repeated  once  or 
twice,  to  remove  the  whole  of  the  hyponitric  acid.  In  this  manner  a 
transparent  and  colourless  acid  may  be  obtained  of  specific  gravity  1  '521 , 
and  containing  15'02  per  cent.  (I  atom)  of  water. 

Impurities  in  Nitric  add, — Hyponitric  acid :  The  concentrated  acid 
is  coloured  yellow  or  yellowish  red  by  this  substance ;  but  the  very  dilute 
colourless  acid  may  also  be  contaminated  with  it.  When  an  acid  which 
contains  hyponitric  acid,  is  diluted  with  2  or  3  parts  of  water,  it  preci- 
pitates sulphur  from  an  aqueous  solution  of  hydrosulphuric  acid  or  of  an 
alkaline  hydrosulphate,  and  iodine  from  alkaline  iodides ;  colours  ferrous 
salts  brown,  and  ferrocyanide  of  potassium  green;  and  decolorizes  a  solu** 
tion  of  indigo,  at  a  degree  of  dilution  at  which  pure  nitric  acid  ceases  to 
have  any  effect  on  it.  (Millon.) — ^The  greater  part  of  the  hyponitric  acid 
may  be  expelled  by  boiling  for  a  short  time  in  a  retort,  when  nitric  acid 
mixed  with  hyponitric  acid  passes  over. — Pelouze  digests  the  acid  with 
peroxide  of  lead;  if  concentrated,  it  does  not  dissolve  any  of  the  lead. — 
Millon  distils  it  mixed  with  y^  of  its  weight  of  bichromate  of  potash;  if, 
however,  the  acid  has  a  greater  specific  gravity  than  1  *48,  it  will  again 
be  partially  resolved  by  distillation  into  oxygen  gas  and  hyponitric 
acid ;  when  this  happens,  Millon  treats  it  with  carbonic  acid  gas  aided 
by  heat,  as  already  described. 

Chlorine,  The  acid  precipitates  a  solution  of  silver.  The  concen* 
trated  acid  may  likewise  be  freed  from  this  impurity  by  heat,  the 
chlorine,  together  with  the  hyponitric  acid  and  a  portion  of  nitric  acid, 
distilling  over  first. — The  old  method  of  preparing  the  precipitated  or 
clumically  pure  nitric  acid  is  rather  troublesome :  the  dilute  acid  is  pre- 
cipitated by  nitrate  of  silver,  decanted  from  the  insoluble  chloride  of 
silver,  and  purified  from  the  excess  of  nitrate  of  silver  by  distillation. 
Bcschcrer  {J.  pr.  Ckem.  16,  317),  recommends  that  the  acid  contain- 
ing chlorine  bo  distilled  over  metallic  silver;  in  this  case,  however, 
some  of  the  chlorine  may  still  pass  over  with  the  nitric  acid.  The  acid 
cannot  be  purified  from  chlorine  by  means  of  oxide  of  lead,  because  the 


JilTRIC  ACID.  393 

chloride  of  lead  dissolyes  in  the  nitric  acid^  and  is  again  decomposed  on 
the  application  of  heat. 

StUpkuric  Acid:  From  soiling  the  neck  of  the  retort,  spirting  of 
the  mixtare,  or  from  using  too  large  a  qnantitj  of  oil  of  vitriol,  and 
heating  too  strongly.  The  nitric  acid  dHuted  with  water  precipitates 
chloride  of  barium. — Purification — hj  redistilling  from  a  small  quan- 
tity of  nitre,  or  precipitating  the  previously  diluted  acid  with  pure 
nitrate  of  baryta  and  distilliug  the  decanted  liquid.  If  chlorine  and 
sulphuric  acid  are  both  present,  the  purification  must  be  effected  by 
precipitating  with  nitrate  of  silver  and  nitrate  of  baryta,  decanting,  and 
distilling. 

Iodine:  In  the  acid  prepared  from  Chili  saltpetre,  as  the  latter  sub- 
stance contains  iodine  (page  247);  hence  this  impurity  is  present  in 
much  of  the  ordinary  nitric  acid  of  commerce.  An  acid  of  this  kind, 
when  distilled  with  oil  of  vitriol,  yields  a  sublimate  of  iodine  after  all 
the  nitric  acid  has  passed  over.  If  it  be  neutralized  with  potassa,  mixed 
with  solution  of  starch,  and  oil  of  vitriol  slowly  added  drop  by  drop,  the 
liquid  assumes  a  blue  colour;  chlorine  does  not  produce  this  effect, 
(Lembert,  J.pr.  Chem,  28,  297.) 

Fotask  and  Soda  tails,  Sesquioxide  of  iron,  and  other  Jued  substances, 
are  left  behind  on  evaporating  the  acid. 

Concentration  of  Nitric  acid. — 1.  An  acid  whose  specific  gravity  is 
below  1'40  yields  when  distilled,  a  weaker  acid,  till  the  residiie  in  the 
retort  has  acquired  a  specific  gravity  of  1*42  (Dalton),  1*415  (Tiinner- 
raann,  Kastn.  Arch.  19,  344),  1,  405,  (Millon),  1*40  (Mitscherlich).— 2. 
An  acid  of  specific  gravity  1*55  yields,  at  the  beginning  of  the  distillation, 
an  acid  of  1*62,  and  then  an  acid  of  1*53;  the  residual  acid  having  a 
specific  gravity  of  1*49.  (Proust.)  The  acid  of  specific  gravity  1*522,  as 
obtained  by  the  distillation  of  1 00  parts  of  nitre  with  96*8  parts  of  oil 
of  vitriol,  yields,  when  partially  distilled  alone,  a  distillate  of  1*54 
and  a  residue  of  1*521.  (Mitscherlich.)— 3.  An  acid  of  specific  gra- 
vity 1*3032  distilled  with  a  fourth  of  its  volume  of  oil  of  vitriol, 
yields  an  acid  of  1*499;  and  this  again  distilled  with  the  same  quantity 
of  oil  of  vitriol,  yields  an  acid  of  1*510  at  18^  (Gay-Lussac.)  Acid 
of  1*41  distilled  with  two  parts  of  oil  of  vitriol  at  a  gentle  heat 
yields  acid  of  1  *5254,  consequently  the  bihydrated  acid.  (Tiinnermann.) 
During  the  distillation  with  oil  of  vitriol,  the  temperature  should  not 
rise  above  140^  or  150^;  otherwise  decomposition  of  the  acid  will  ensue: 
by  repeated  distillation  with  oil  of  vitriol,  an  acid  is  obtained  of  specific 
gravity  1*520,  and  boiling  at  86°  to  88°.  (Pelouze,  ilnn.  Chim,  Phys. 
77,  51.>  The  acid  concentrated  by  means  of  oil  of  vitriol  is  purified  from 
any  sulphuric  acid  mixed  with  it,  oy  distilling  it  alone  or  with  nitre. 

Properties.  Colourless,  transparent  liquid  (frequently  however  co- 
loured yellow  by  h3rponitric  acid).  Its  highest  specific  gravity  is  1*62  [1] 
(Proust),  1-564  (Kirwan,  Mitscheriich),  1*552  at  20^  (Millon),  1*55 
(H.  Davy),  1*52  (Pelouze),  1513  (Th^nard);  the  less  water  it  contains 
the  higher  is  its  specific  gravity.  Acid  of  specific  gravity  130  freezes 
at — 19°  (Dalton);  a  stronger  acid  requires  a  temperature  of — 54°,  when 
it  solidifies  to  a  mass  like  butter.  The  strongest  acid  boils  below  1 00% 
and  is  rendered  weaker  by  boiling,  in  consequence  of  strong  acid  being 
evolved ;  a  more  dilute  acid  boils  at  a  temperature  higher  than  the  boiling 
point  of  water,  and  becomes  stronger  by  boiling,  a  weaker  acid  being 


894  NrmOGBN. 

eTolred    Aoeording  to  Daiton,  sn  acid  of  speoifio  gravity  1*42,  becomes 
neither  stronger  nor  weaker  by  boiling ;  and  its  boiling  point  is  at  the 
highest  not  above  120^  (248®  F.).     According  to  Mitscherlich,  an  acid 
of  specific  gravity  r40  behaves  in  the  following  manner;  it  contains  56 
percent,  of  acid,  and  boils  between  120}^  and  121"^;  but  if  platinum  wire  is 
not  put  into  it  the  ebullition  becomes  percussive,  and  the  temperature 
may  even  rise  as  high  as  125^.     This  percentage  of  acid  approaches 
nearest  to  the  proportion  of  1  atom  of  nitric  acid  to  5  atoms  of  water; 
the  mutual  condensation  appears  then  to  be  greatest  in  a  mixture,  in 
which  the  acid  and  water  contain  the  same  amount  of  oxygen.      Graham 
(Ann.  PJuirm,  29,  12)  and  Bineau  {Ann.  Chim.  Pkys.  68,  417)  suppose 
that  the  acid  which  remains  after  distillation  contains  not  5  but  4  atoms 
of  water.     According  to  Millon,  a  stronger  acid  is  reduced  by  prolonged 
boiling  in  a  retort,  to  a  density  of  1*419  at  the  lowest;  such  an  acid  con- 
tains 4  atoms  of  water ;  a  weaker  acid  never  attains  a  density  higher  than 
1'405,  corresponding  to  4^  atoms  of  water.     When  a  dilute  acid  is  boiled 
without  platinum  wire,  the  boiling  point  quickly  rises  as  high  as  125® 
or  128^,  at  which  temperature  acid  of  1*2  distils  over;  if  platinum  wire  be 
then  introduced  into  the  retort,  the  boiling  point  sinks  to  122*5^  and  the 
acid  which  passes  over  has  a  specific  gravity  of  only  1*175 :  it  is  there- 
fore decidedly  weaker  than  the  earlier  distillate.     Acid  of  specific  gra- 
vity 1*522  boils  at  86°.  (Mitscherlich.)     The  boiling  point,  however,  gra- 
dually rises  to  123^  at  which  temperature,  a  sraaU  quantity  of  acid  of 
specific  gravity  1  *484,  containing  2  atoms  of  water,  is  obtained.  (Millon.) 
Aqueous  nitric  acid  hajs  a  faint,  but  characteristic  odour,  and  a  veiy 
sour  taste ;  it  colours  litmus  red ;  exerts  a  highly  caustic  and  corrosive 
action  or  organic  substances,  and  stains  those  containing  nitrogen,  such  as 
the  skin  and  nails,  of  a  yellow  colour.     The  concentrated  acid  absorbs 
water  from  the  atmosphere,  but  less  greedily  than  sulphuric  acid.     Acid 
of  specific  gravity  1*526,  evolves  heat  when  mixed  with  snow;  acid  of 
specific  gravity  1*420,  on  the  contrary,  produces  cold  with  snow,  but 
still  evolves  heat  when  mixed  with  water. 

Aaueous  nitric  acid  when  heated  dissolves  copper  filings,  with  evolu- 
tion of  nitric  oxide  gas  which  produces  yellowish  red  vapours  in  the  air. 
The  resulting  solution  is  green;  and  when  moderately  concentrated, 
attacks  tinfoil,  with  rise  of  temperature  and  effervescence,  producing 
a  white  powder  which  evolves  ammonia  when  treated  with  potash. — 
Mixed  with  hydrochloric  acid,  it  dissolves  gold  leaf  (the  limit  of  this 
reaction  is  attained  when  1  part  of  nitric  acid  of  specific  gravity  ]  -32 
is  diluted  with  239  parts  of  water,  the  solution  then  requiring  24  hours 
for  its  completion ;  Harting,  J.  pr.  Chem.  22,  48); — ^with  oil  of  vitriol 
to  which  a  solution  of  ferrous  sulphate  has  been  added,  it  forms  a  red 
mixture; — it  changes  the  blue  colour  of  solution  of  sulphate  of  indigo 
to  brownish-yellow,  especially  when  aided  by  heat. 

Calculation  of  the  first,  second,  third,  fourth,  and  fifth  hydrates  of  nitric  acid. 
N0>     1       54        85-71  I  1    54    73    I  1     54      6667  1  1     54        60  I  1     54      54*55 


HO      1         9        14-29     2     rJ    25      3     27      3333     4     36       40     5    45     45*45 


1       63      10000  I  1     72  100  I  1     81    10000  |  1     90     100  |  1     99    100*00 


NITRIC  ACm. 


S9i 


Amount  of  Pure  or  Anhydrous  NUric  acid  in  Aqueous  NUrio  Aeid  of 
various  strengths. 


According  to  Kirwan  and 
Dalton. 

According  to  Uro  {Schw,  35, 446). 

8p.gr. 

Percent. 

Boiling 

Sp.gr. 

Percent. 

Sp.gr. 

Per  cent. 

of  Acid. 

Point. 

of  Acid. 

of  Add. 

1-62 

82-7 

38'»? 

1-5000 

79-700 

1-2887 

39053 

1-54 

72-5 

80? 

1-4940 

77-303 

1-2705 

36-662 

1-50 

680 

99 

1-4850 

74-918 

1-2523 

34  271 

1-45 

580 

115 

1-4760 

72-527 

1-2341 

31-880 

1-42 

54-4 

120 

1-4670 

70-136 

1-2148 

29-489 

1-40 

51-2 

119 

1-4570 

67-745 

1-1958 

27  098 

1-35 

44-3 

117 

1-4460 

65-354 

1-1770 

24-707 

1-30 

37-4 

113 

1-4346 

62-936 

1-1587 

22-316 

1-26 

32-3 

111 

1-4228 

60-572 

11403 

19-925 

1-22 

28-6 

109 

1-4107 

58-181 

1-1227 

17-534 

1-20 

25-4 

108 

1-3978 

55-790 

11051 

15-153 

118 

230 

106 

1-3833 

53-399 

1-0878 

12-752 

117 

210 

105 

1-3681 

51-063 

10708 

10-361 

116 

19-3 

104-5 

1-3529 

48-617 

1-0540 

7-970 

115 

17-8 

104 

1-3376 

46-226 

1-0375 

6-579 

114 

16-6 

104 

1-3216 

43-833 

1*0212 

3188 

1-3056 

41*444 

1-0053 

0-797 

According  to  Mitscherlich,  acid  of  specific  ffravity  1*54  contains  88*82; 
acid  of  specific  grayity  1*522,  88*17;  and  acid  of  specific  grayity  1*40, 
44  per  cent,  of  anhy^oos  nitric  acid. — (Richter's  Tables,  ^tdchiometrie, 
3,  64.) 

Decompositions. — 1.  a.  Nitric  acid  transmitted  throngh  a  porcelain 
Inbe  heated  to  whiteness,  is  resolved  into  oxygen  gas,  nitrogen  gas,  and 
an  acid  of  less  strength.---^.  If  the  porcelain  tube  is  but  feebly  ignited, 
the  nitric  acid  is  resolved  into  oxygen  and  hjrponitric  acid.  Acid  of 
specific  gravity  1*522  (Mitscherlich),  and  monohydrated  nitric  acid 
(HO,  NO*)  is  partially  decomposed  even  by  distillation,  with  formation  of 
yellowish  red  vapours.  The  sun's  rays  also  decompose  an  acid  of  specific 
gravity  not  less  than  1*4;  the  liquid  assumes  a  yellow  colour  and  evolves 
oxygen  gas.  (Scheele;  Gay-Lussac.)  Accordmg  to  Millon,  the  mono- 
hydrated acid  becomes  coloured  in  the  sun's  rays,  only  when  its  tem- 
perature reaches  30°  or  40*^.— «.  A  weaker  acid  mixed  with  oil  of  vitriol, 
likewise  undergoes  decomposition  on  exposure  to  the  sun's  rays.  (Gay- 
Lussac.)  When  a  mixture  of  nitric  acid  with  4  parts  of  oil  of  vitriol 
is  gently  heated,  the  nitric  acid  is  given  oflT  in  the  form  of  oxygen  gas 
and  hyponitrio  acid,  leaving  dilute  sulphuric  acid  behind.  (Th^nard.)— 
100  parts  of  nitric  acid  of  specific  gravity  1*448  distilled  with  500 
parts  of  oil  of  vitriol  at  a  gentle  heat  yield  88  parts  of  nitric  acid  of 
specific  gravity  1*520;  the  latter  freed  by  moderate  heat  from  the  hypo- 
nitric  acid  which  it  contains,  mixes  with  6|-  times  its  volume  of  oil  of 
vitriol,  without  perceptible  rise  of  temperature ;  and  the  colourless  mix- 
ture, which  emits  white  fumes,  yields,  when  distilled  below  150°,  (302® 
F.)  nitric  acid  of  specific  gravity  1*520.  The  same  results  ensue  after 
a  third  distillation  with  oil  of  vitriol :  so  that  the  oil  of  vitriol  does  not 
separate  the  last  portions  of  water  from  the  nitric  acid,  nor  does  it  in  any 
way  effect  its  deoompoBitioi:^;-*but    the  heat  employed  in  distillation 


396.  >1TR0CBN. 

decompoees  a  small  qoantity  of  the  acid.  (Pelouze,  Ann,  Chim,  Phya. 
77,51.) 

2.  a.  Hydrogen  gas  does  not  affect  nitric  acid  at  ordinary  tempera* 
tnres;  bat  when  transmitted  together  with  its  vapour  throngh  a  red-hot 
porcelain  tube,  it  gives  rise  to  violent  detonation  and  separation  of  nitrogen 
gas.  (Fourcroy.)  Hydrogen  gas  charged  with  vapour  of  nitric  acid  and 
parsed  over  spongy  platinum  raises  it  to  a  red  heat,  and  yields  water  and 
ammonia.  (Knhlmann.) — 6.  Diamond  is  not  oxidized  by  boiling  nitric  acid. 
Ignited  charcoal  bums  vividly  in  contact  with  the  concentrated  acid.— «. 
Nitric  acid  gently  heated  with  boron,  yields  boracic  acid,  nitric  oxide  gas, 
and  nitrogen  gas.  (Gay-Lnssac  and  Thenard.) — d.  Phosphorus  is  dissolved 
by  nitric  acid  of  specific  gravity  1*2  on  the  application  of  a  gentle  heat, 
nitric  oxide  gas  and  a  small  quantity  of  free  nitrogen  being  evolved,  the 
temperature  of  the  liquid  rising,  and  the  phosphorus  being  converted  into 
phosphorous  and  phosphoric  acids  (the  statement  of  Wittetock,  Berl,  Jak- 
resb.  33,  2,  142,  that  nitrous  oxide  gas  is  also  formed,  is  not  in  accordance 
with  the  author's  own  obseryations) ;  on  evaporating  the  solution,  the  phos- 
phorous acid  is  wholly  oxidized  by  the  remaining  nitric  acid,  and  converted 
into  phosphoric  acid,  the  change  being  attended  with  evolution  of  nitric 
oxide  gas. — Ammonia  is  not  formed  in  this  reaction.  (L.  A.  Buchner.) 
Concentrated  nitric  acid  effervesces  violently  with  phosphorus  at  ordinary 
temperatures, — the  action  increasing  in  violence  till  the  heat  disengaged  is 
sufficient  to  i£:nite  the  phosphorus,  which  then  burns  in  the  acid  yapours 
with  great  splendour.  Even  the  strongest  nitric  acid  at  first  converts  a  por- 
tion of  the  phosphorus  into  phosphorous  acid.  (Schonbein.)  Paper  mois- 
tened with  concentrated  nitric  acid  and  laid  on  a  flat  piece  of  phosphorus, 
detonates  when  struck  with  a  hammer.  (BrugnatelH.^  Phosphoric  oxide 
dissolves  in  dilute  nitric  acid  more  rapidly  than  phosphorus  itself ;  accord- 
ing to  Pelouze,  the  concentrated  acid  inflames  it.  Phosphorous  acid  is 
converted  by  nitric  acid  into  phosphoric  acid,  the  action  being  attended 
with  evolution  of  nitric  oxide  gas.  Phosphuretted  hydrogen  gas  is  vio- 
lently decomposed  by  concentrated  nitric  acid.  (Graham.)— «.  Sulphur  is 
oxidized  with  some  difficulty  by  nitric  acid  and  converted  into  sulphuric 
acid ;  the  action  however  is  more  rapid  in  proportion  as  the  sulphur  is 
more  finely  divided  and  the  acid  stronger.  Dilute  nitric  acid  repeatedly 
saturated  with  sulphurous  acid  converts  the  latter  into  sulphuric  acid. 
^  Vid.  Dana,  Fkil.  Hag.  J,  3, 1 20.)  If  half  an  ounce  of  nitric  acid  be  poured 
into  a  bottle  full  of  hydrosulphuric  acid  gas,  a  blue  flame  bursts  with  a 
slight  noise  from  the  mouth  of  the  bottle,  after  a  few  seconds;  at  the  same 
time,  red  fumes  are  produced,  the  hydrogen  and  part  of  the  sidphur  are 
oxidated,  and  the  rest  of  the  sulphur  is  separated  in  the  free  state.  If  sul- 
phuretted hydrogen  gas  is  passed  for  seyeral  hours  through  a  mixture  of 
1  measure  of  concentrated  nitric  acid  and  from  2  to  4  measures  of  water, 
heat  is  generated,  nitric  oxide  gas  is  disengaged,  and  sulphur  separated ; 
and  the  liquid  is  afterwards  found  to  contain  sulphate  of  ammonia  and 
free  sulphuric  acid.  (Johnston,  iT.  Ed.  J.  of  Sc.  6,  65;  9i\soSchw.  64,  301 ; 
also  Pogg.  24,  354.)  Nitric  acid  perfectly  free  from  hyponitric  acid  does 
not  decompose  an  aqueous  solution  of  hydrosulphuric  acid  at  ordinary 
temperatures.  (A.  Vogel,  Millon.)— /,  Selenium  is  converted  by  warm 
nitric  acid  into  selenious  acid.  (Berzelius.) — g.  Iodine,  gently  heated  with 
highly  concentrated  nitric  acid,  yields  iodic  acid  and  fumes  of  hyponitric 
acid.  Hydriodic  acid  and  nitric  acid  act  upon  each  other  in  such  a  man- 
ner as  to  produce  water,  iodine,  and  nitric  oxide  : 

SHI  +  N0»  «  3H0  +  31  +  NO" . 


NITRIC  ACID.  3&7 

^~h.  Aqneons  hydrochloric  acid  and  nitric  acid  form  chlorine,  water,  and 
hyponitric  acid.  (Vid.  Aqua  re^ia,) — i.  Nitric  acid  absorbs  nitric  oxide 
gas  in  greater  abundance,  the  smaller  the  quantity  of  water  it  contains 
and  the  lower  the  temperature;  and  is  converted,  by  giving  up  oxygen 
to  the  nitric  oxide,  into  hyponitric  acid  and  nitrous  acid,  the  colour  of 
the  mixture  becoming  first  yellow,  then  green,  and  lastly  blue. 

2NO*  +  NO«  =  3NO*  and  N0»  +  2NO*  =  3N0». 
— Nitric  acid  of  specific  gravity  1*115  absorbs  but  little  of  the  gas  at 
ordinary  temperatures,  and  remains  colourless ;  acid  of  specific  gravity  1  '82 
becomes  green;  acid  of  1*41,  orange;  and  acid  of  specific  gravity  1-5 
acquires  a  dark-reddish  colour;  the  latter  mixture  when  heat^  generally 
evolves  hyponitric  acid.  (Th6nard.)  When  a  current  of  nitric  oxide  sas  is 
passed  through  nitric  acid  containing  more  than  5  atoms  of  water  and  sur« 
rounded  with  a  freezing  mixture,  a  blue  li(|uid  is  formed,  from  which  blue 
nitrous  acid  may  be  obtained  by  distillation ;  when  less  than  5  atoms  of 
water  is  present,  a  yellow  liquid  is  produced  containing  hyponitric  acid. 
(Fritzsche.)  According  to  Priestley  {Experim.  and  Ob&ervat.  3,  121), 
strong  nitric  acid,  by  absorbing  nitric  oxide,  becomes  first  yellow,  then 
orange,  then  olive-green,  then  light-green,  and  lastly  greenish  blue ;  the 
bulk  and  volatility  of  the  acid  are  at  the  same  time  considerably  increased, 
and  a  dense  red  vapour  is  evolved*. — k,  [For  the  decomposition  with 
ammonia,  see  Nitrate  of  Ammonia.^ 

3.  Nitric  acid,  at  ordinary  temperatures  or  at  the  boiling  point,  oxidizes 
all  metals,  excepting  silicium,  titanium,  tantalum,  platinum,  rhodium,  and 
iridium,  and  (under  ordinary  circumstances,)  gold.  The  resulting  metallic 
oxides  (except  those  of  tungsten,  tellurium,  tin,  and  arsenic)  combine  with 
the  undecomposed  portion  of  the  acid  and  form  salts  which  (with  the  excep- 
tion of  nitrate  of  antimony)  dissolve  in  the  liquid,  provided  at  least  it  is 
not  too  concentrated.  In  this  reaction,  the  portion  of  acid  which  oxidizes 
the  metal  is  converted  sometimes  into  hyponitric  acid,  sometimes  into 
nitric  oxide  {Sck,  24),  nitrons  oxide  {Sch.  25),  or  nitrogen  gas,  or — if 
the. metal  at  the  same  time  decomposes  water,  the  hydrogen  of  which 
then  combines  with  the  nitrogen  of  the  acid — into  ammonia.  {Sch.  85.) 
The  last-mentioned  re-action  takes  place  with  tin,  and  likewise,  according 
to  Kuhlmann  {Ann,  Fharm,  27,  27),  with  zinc,  cadmium,  and  iron. 
Which  of  the  above  products  is  formed,  depends  partly  on  the  affinity  of 
the  metal  for  oxygen,  partly  on  the  temperature  and  concentration  of 
the  acid. 

At  ordinary  temperatures,  nitric  acid  converts  tin  into  binoxide,  with 
great  rise  of  temperature  and  evolution  of  nitric  oxide,  nitrous  oxide, 
nitrogen,  and  ammonia.  When  1  part  of  tin  is  digested  with  16  parts 
of  nitric  acid  of  specific  gravity  1  '2,  the  large  excess  of  acid  prevents  the 
temperature  from  a  rising  beyond  33°,  and  consequently,  perfectly  pure 
nitrous  oxide  gas  is  disengaged,  though  not  in  great  abundance;  with  a 
smaller  proportion  of  acid,  in  which  case  the  heat  rises  to  44°,  the  nitrons 
oxide  is  mixed  with  nitric  oxide  gas.  Nitric  acid  of  specific  gravity  1*2 
diluted  with  from  one  to  three  times  its  bulk  of  water,  evolves  pure  nitrous 
oxide  gas  when  acted  upon  by  zinc ;  when  not  diluted,  it  yields  nitrous  oxide 
gas  contaminated  with  nitric  oxide,  the  quantity  of  the  latter  increasing 

*  The  oonversion  of  nitric  acid  into  hyponitric  acid  by  the  action  of  nitric  oxide  gas^ 
and  the  decomposition  of  hyponitric  acid  by  water  into  nitric  acid  and  nitric  oxide  gas, 
induced  Priestley,  Berthollet,  Sir  H.  Davy,  and  Thomson,  to  regard  hyponitric  acid,  not 
as  a  direct  compound  of  nitrogen  with  oxygen,  but  as  a  combination  of  nitric  acid  with 
nitric  oxide. 


908  NITBOOBH* : 

9m  the  temperaiaM  rises.  Nitric  acid  of  specific  gravity  1*2  dilated  with 
three  times  its  balk  of  water,  does  not  attack  iron  at  ordinary  temperar 
tures ;  if  diluted  with  only  twice  its  bulk,  it  first  evolyes  nitrous  oxide 
gas  mixed  with  a  small  quantity  of  nitric  oxide,  but  towards  the  end 
of  the  action,  the  latter  compound  only  is  disengaged.  (Pleischl.)  When 
copper  is  digested  in  nitric  acid  of  specific  gravity  1*217  at  a  temperature 
of  —10°  (and  this  temperature  is  kept  up),  nitrous  oxide  is  evolved,  mixed 
with  a  small  quantity  of  nitric  oxide  gas  (Millon);  dilute  nitric  acid 
acted  upon  by  copper  at  ordinary  temperatures  evolves  pure  nitric  oxide 
gas ;  but  if  the  temperature  rises,  or  the  acid  is  more  concentrated,  nitro- 
gen is  likewise  disengaged.  Antimony,  bismuth,  lead,  mercury,  and  silver 
liberate  nitric  oxide  gas ;  but  if  heat  is  applied  or  if  the  acid  is  strong, 
nitrogen  gas  is  likewise  evolved. 

The  transference  of  the  oxygen  from  the  nitric  acid  to  the  metal,  is 
always  attended  with  evolution  of  heat,  by  which  the  process  of  oxidation 
— slow  at  first — becomes  accelerated,  and  sometimes  ends  in  actual  com* 
bastion.  Concentrated  nitric  acid  poured  on  heated  iron  filings  or  on 
melted  bismuth,  zinc,  or  tin,  causes  the  metal  to  become  incandescent, 
(Proust.) 

Nitric  acid  vapour  transmitted  over  ignited  metals,  yields  metallio 
oxide  with  nitrogen  and  hydrogen  gases,  if  the  metals  are  capable  of  de- 
composing water, — ^when  this  is  not  the  case,  the  products  are  metallic 
oxide,  nitrogen  gas  and  water. 

Woodhouse  first  pointed  out  that  certain  metals,  such  as  tin,  copper, 
and  silver,  remain  unchanged  in  highly  concentrated  nitric  acid,  but  are 
instantly  oxidized  on  the  addition  of  water.  The  circumstances  under 
which  these  anomalies  and  the  so-called  passive  condition  of  various 
metals  are  produced,  have  been  already  discussed  (1.  353 — 363),  where  it 
has  been  shown  that  the  formation  of  a  thin  stratum  of  oxide  or  nitrate 
on  the  surface  of  the  metals,  is  in  all  probability  the  cause  which  prevents 
the  farther  action  of  the  acid.  The  following  observations  likewise  tend 
to  the  same  conclusion. 

Tin  is  not  attacked  by  very  strong  nitric  acid,  even  on  boiling.  Strong 
boiling  nitric  acid  does  not  dissolve  a  trace  of  lead  or  silver,  inasmuch  as 
the  nitrates  of  lead  and  silver  are  insoluble  in  that  menstruum.  Zinc,  bis- 
muth, copper,  and  mercury,  on  the  contrary,  dissolve  in  strong  nitric  acid, 
though  less  readily  than  in  the  same  acid  when  more  dilate,  because  their 
salts  are  more  or  less  soluble  in  the  concentrated  acid.  But  nitric  acid 
mixed  with  alcohol  acts  but  feebly  on  bisnmth,  zinc,  and  copper,  and  not 
at  all  on  mercury,  because  the  nitrates  of  the  first  three  metals  are  but 
slightly  soluble,  and  that  of  mercury  perfectly  insoluble  in  alcohol. 
(Braconnot,  Ann.  Chim.  Fkyt.  52,  286;  also  Pogg.  29,  173.) 

Nitric  acid,  for  the  most  part,  oxidizes  metals  only  when  it  contains 
nitrous  acid.  The  latter  first  gives  off  nitric  oxide  and  forms  a  nitrite, 
which  at  the  moment  of  its  formation  is  converted  by  the  nitric  acid  into 
a  nitrate.  The  nitrous  acid  thus  set  free,  together  with  that  produced  by 
the  action  of  the  nitric  oxide  on  the  nitric  acid,  again  acts  upon  a  fresh 
quantity  of  metal,  forming  nitric  oxide  and  a  metallic  nitrite,  &c  In  this 
manner  the  quantity  of  the  nitrous  acid  continually  increases,  and  with  it 
also  the  intensity  of  the  chemical  action.  [Although  nitrous  acid  contains 
less  oxygen  than  nitric  acid,  it  appears  to  part  with  that  element  more 
readily,  because  its  affinity  for  water  is  less  than  that  of  nitric  acid; 
vid,  L,  144.]  At  —18''  (;— 0°  F.)  monohydrated  or  bihydrated  nitric  acid 
(free  from  nitrous  acid)  does  not  act  on  tine;  but  the  metal  becomes 


NITRIC  ACT).  aw 

«0T6red  with  a  yellowish  white  film,  which  probably  pieyents  farthet 
action :  at  a  few  degrees  abore  —18°,  however,  the  film  appears  to  be 
dissolved;  for  as  soon  as  the  vessel  is  taken  out  of  the  freezing  mixture,  a 
violent  action  commences.  In  an  acid  containing  4  or  4^  atoms  of  water, 
the  zinc  retains  its  metallic  lustre,  and  remains  unaltered  at  —18%  but  at 
0^  it  is  violently  attacked.  Still  weaker  acid  acts  even  at  —18°. 
Polished  balls  of  iron  immersed  in  nitric  acid  containing  from  1  to  2 
atoms  of  water,  and  free  from  nitrous  acid,  become  covered,  sometimes  with 
a  black,  sometimes  with  a  blue  or  blue  and  yellow  film,  which  has  the 
properties  of  ferroso-ferric  oxide  as  produced  by  the  rusting  of  iron.  In 
this  state  they  are  not  attacked  by  a  weaker  acid,  unless  the  temperature 
is  raised.  An  acid  containing  4  or  4)-  atoms  of  water  does  not  affect  the 
metallic  lustre  of  iron,  or  attack  it  in  any  way,  unless  aided  by  heat.  A 
still  weaker  acid  dissolves  the  iron,  though  but  slowly,  forming  a  green 
solution  [owing  to  the  presence  of  nitric  oxide  which  is  absorbed  by  the 
ferrous  nitrate].  Nitric  acid,  of  whatever  degree  of  concentration,  if  free 
from  nitrous  acid,  does  not  attack  arsenic  or  antimony  at  the  tempera- 
ture of  20°  (68°  F.)  ;  only  the  strongest  acid  acts  slightly  on  antimony,  but 
without  effervescence.  Bismuth  retains  its  metallic  lustre  at  +20°  in 
bihydrated  nitric  acid  free  from  nitrous  acid;  it  is  rapidly  dissolved  in 
acid  containing  4  or  4^  atoms  of  water ;  but  remains  unattacked  in  acid 
of  specific  gravity  1-108.  In  the  latter  case,  heat  or  a  current  of  nitrio 
oxide  gas  sets  up  the  action,  but  it  may  be  arrested  again  by  surrounding 
the  vessel  with  a  freezing  mixture,  or  by  the  addition  of  ferrous  sulphate* 
Tin  behaves  in  a  similar  manner  to  bismuth.  Acid  of  specific  gravity 
1*07,  and  not  containing  nitrous  acid,  does  not  attack  copper  at  +20 
(but  hot  acid  of  sp.  gr.  1  '07,  or  stronger  acid  acts  on  the  copper) ;  a  cur- 
rent of  nitric  oxide  gas  or  the  addition  of  a  few  drops  of  nitrite  of  potassa 
sets  up  the  action  ;  the  larger  the  quantity  added,  the  more  rapidly  is  the 
copper  dissolved.  If  the  action  has  been  commenced  by  a  current  oi 
nitric  oxide  gas,  the  addition  of  ferrous  sulphate,  which  combines  with 
the  gas,  arrests  it  instantaneously.  The  transmission  of  oxygen,  car- 
bonic acid,  or  nitrous  oxide  gas  through  acid  of  specific  gravity  1-07,  or 
the  addition  of  chloride  of  lime  and  carbonates,  does  not  bring  about  the 
solution  of  the  metal.  If  the  action  has  been  set  up  by  the  addition 
of  nitrite  of  potassa,  it  ceases  on  plunging  the  vessel  into  a  freezing  mix- 
ture, when  the  acid  begins  to  solidify;  it  recommences,  however,  as  soon 
as  the  vessel,  by  exposure  to  the  air,  has  attained  the  temperature  of  20° ; 
a  proof  that  the  action  caused  by  the  addition  of  nitric  oxide  gas  or  nitrite 
of  potassa  is  not  due  to  the  disengagement  of  heat.  Acid  of  specific  gra- 
vity 1*552,  which  contains  rather  less  than  1  atom  of  water,  does  not  attack 
copper  at  +20°;  an  acid  containing  from  1  to  4^  atoms  of  water  rapidly 
dissolves  it  at  +20®,  but  not  at  —18°.  When  copper  is  immersed  in 
monohydrated  acid  at  —18°,  the  acid  assumes  a  pale  green  colour,  while 
the  metal  becomes  covered  with  a  bluish  crust,  which  prevents  the  further 
action  of  the  acid,  even  at  +  20°,  and  is  insoluble  in  strong  nitric  acid, 
but  dissolves  readily  in  water.  In  nitric  acid  containing  4  or  4^  atoms  of 
water,  copper  retains  its  metallic  lustre  at  — 18°;  but  on  removing  the 
vessel  from  the  freezing  mixture,  the  metal  becomes  covered  with  a  bluish 
crust,  without  any  further  action  taking  place,  unless  the  whole  is  fre- 
quently shaken.  Nitric  acid  of  specific  gravity  1*217  begins  to  act  on 
copper,  even  at  —10°;  and  acid  of  1*108,  at  2°.  Silver  and  mercury 
behave  like  copper.  Mercury  is  completely  oxidized  by  monohydrated 
nitric  acid,  even  in  the  freezing  mixture,  but  much  more  slowly  than  at  a 


400  NITAOGSK. 

temperatnre  of  20°,  alihough  an  insoluble  product  is  formed,  probably  on 
account  of  the  mobilitv  of  the  mercury.  In  pure  dilute  nitric  acid  mer- 
cury remains  unaltered,  unless  heat  is  applied  or  nitrite  of  potash  added. 
Silver  immersed  in  rather  strong  and  pure  acid  becomes  covered  sometimes 
with  a  white,  sometimes  with  a  grey  crust,  which  prevents  the  further  action 
the  acid ;  in  nitric  acid  containing  4^  atoms  of  water,  it  dissolves  only  on 
the  application  of  heat  or  the  addition  of  nitrite  of  potash.  (Millon.) 

4.  Most  organic  compounds  become  strongly  heated  by  contact  with 
concentrated  nitric  acid,  frequently  even  to  inflammation,  e.g.,  oil,  aJcohol, 
charcoal,  &c.  The  nitric  acid  is  thereby  converted  into  nitric  oxide,  or 
frequently  into  nitrogen  gas. 

Nitric  acid  aho  combines :  h.  with  Peroxide  of  Hydrogen  and  Water 
(p.  78,  and  Ann.  Chim.  Phys.  8,306;  9,94), 

c.  With  Hyponitric  acid  and  Water. 

d.  With  Hydrochloric  acid  and  Water. 

e.  With  Salifiable  Bases  it  forms  a  class  of  salts  called  N Urates,  Azo- 
totes,  or  formerly,  Saltpetres.  These  salts  are  obtaiucd,  sometimes  by 
exposing  an  organic  substance  mixed  with  a  strong  salifiable  base  to  the 
air  (p.  388),  sometimes  by  the  direct  combiuation  of  nitric  acid  with  the 
base  or  its  carbonate,  or  with  an  oxide  of  a  metal  formed  at  the  expense  of 
the  acid  itself.  Concentrated  nitric  acid  does  not  decompose  carbonate  of 
soda  deprived  of  its  water  by  fusion,  or  carbonate  of  lead,  or  the  carbonates 
of  baryta  and  lime,  even  at  a  boiling  heat;  doubtless  because  the  nitrates 
of  all  these  bases  are  insoluble  in  strong  nitric  acid,  and  the  portion  of  salt 
first  produced  protects  the  remainder  by  forming  a  crust  around  it.  Car- 
bonate of  potash,  on  the  contrary,  is  readily  decomposed,  because  the  nitrate 
of  potash  is  soluble  in  concentrated  nitric  acid.  (Braconnot.)  Nitric  acid 
mixed  with  alcohol  does  not  act  on  carbonate  of  potash,  and  but  slowly 
on  carbonate  of  soda,  baryta,  or  magnesia  ;  the  carbonates  of  strontia  and 
lime,  however,  are  rapidly  dissolved  by  it  (Pelouze,  Ann.  Ckim.  Phys.  50, 
434 ;  also  Pogg.  26,  343) ;  because  the  nitrates  of  strontia  or  lime  are 
readily  soluble  in  alcohol,  whereas  nitrate  of  potash  is  precipitated  from 
its  solution  in  nitric  acid  on  the  addition  of  alcohol.  Even  hydrate  of 
potash  resists  the  action  of  nitric  acid  when  mixed  with  a  large  quantity 
of  ether,  till  heat  is  applied  or  the  mixture  shaken.  (Braconnot,  Ann. 
Chim.  Phys.  52,  286;  also  Pogg.  29,  173.)  Most  of  the  nitrates  have  a 
cooling  taste. 

All  nitrates  are  decomposed  at  a  red  heat :  some  of  them  yield  tolerably 
pure  oxygen  gas  at  first,  and  are  themselves  converted  into  nitrites :  after- 
wards they  give  off  oxygen  gas  mixed  with  nitrogen  (e.  g.  nitrate  of 
potash).  Others  which  retain  the  nitric  acid  less  powerfully,  yield  oxy- 
gen gas  and  hyponitric  acid  (e.  g.  nitrate  of  lead) ;  others  again  which 
retain  their  nitric  acid  still  less  forcibly  evolve  it  in  an  undecomposed 
form,  together  with  the  water  which  they  contain  {e.  g.  nitrate  of  alumina). 
The  base  sometimes  remains  unchanged  (as  in  the  lead  salt) ;  sometimes 
it  is  raised  to  a  higher  degree  of  oxidation  (as  in  the  case  of  manganous 
nitrate),  and  sometimes  reduced  to  the  metallic  state  (as  with  nitrate  of 
silver).  Nitrate  of  ammonia  undergoes  a  still  more  peculiar  change. 
Combustible  bodies  both  metallic  and  non-metallic  decompose  the  siuts 
of  nitric  acid,  but  in  most  cases  not  below  a  red  heat ;  the  decomposition 
is  attended  with  vivid  incandescence  and  often  with  explosion,  inasmuch 
as  the  nitrogen  of  the  nitric  acid  is  disengaged  in  the  gaseous  form,  and 
acquires  a  high  degree  of  elasticity,  in  consequence  of  the  heat  evolved  by 
ihe  union  of  the  oxygen  of  the  nitric  acid  with  the  combustible  matter. 


NITRIC  ACID.— NITRATES.  401 

Sach  18  the  case  with  charcoal^  boroD,  phosphorus,  sulphur,  iron,  zinc, 
tin,  &c.  The  substance  oxidized  by  the  oxygen  of  the  nitric  acid  fre- 
quently unites — at  least  in  part — with  the  remaining  salifiable  base. 
Phosphorus  explodes  with  some  of  the  nitrates,  merely  on  being  struck. 
Tin  decomposes  some  of  them  even  at  ordinary  temperatures.  When 
sulphuretted  hydrogen  is  passed  through  a  solution  of  some  of  the  nitrates, 
as  that  of  baryta,  the  gas  and  the  nitric  acid  act  upon  each  other,  espe- 
cially if  heat  be  applied,  in  such  a  manner  as  to  produce  sulphur,  sulphu- 
ric acid,  and  ammonia.  (Johnston.) 

Hydrochloric  acid  added  in  excess  to  a  salt  of  nitric  acid,  yields  a 
metallic  chloride  (or  salt  of  hydrochloric  acid)  hyponitric  acid,  and  chlo- 
rine. (Scheme  98.) 

KO,NO»  +  2HC1  =  KCl  +  2HO  +  NO*  +01. 

Hence  the  salts  of  nitric  acid  (and  also  those  of  selenic,  iodic,  bromic,  and 
chloric  acid)  impart  to  hydrochloric  acid  the  property  of  dissolving  gold 
leaf  on  the  application  of  heat.     The  nitrates  are  decomposed  at  ordinary 
temperatures  by  sulphuric  acid;  at  slightly  elevated  temperatures,  by 
phosphoric,  arsenic,  and  hydrofluoric  acid ;  and  at  a  red  heat  by  boracic, 
and  frequently  also  by  silicic  acid,  the  base,  in  all  these  cases,  entering 
into  combination  with  the  decomposing  acid.     Hence  powdered  nitrates 
mixed  with  oil  of  vitriol  give  out  a  smell  of  nitric  acid;  and  when  heated 
with  powdered  bisulphate  of  potash,  evolve  yellowish  red  vapours.  Mixed 
with  copper  turnings  and  heated  with  moderately  dilute  sulphuric  acid, 
they  form  a  greenish  blue  solution,  and  evolve  nitric  oxide  gas,  which  pro- 
duces yellowish  red  fumes  of  hyponitric  acid  by  contact  with  the  atmo- 
spheric air  contained  in  the  vessel.     When  a  concentrated  solution  of  a 
nitrate  is  mixed  with  ten  times  its  volume  of  oil  of  vitriol,  then  cooled, 
and  mixed  or  covered  with  a  strong  solution  of  ferrous  sulphate,  it  as- 
sumes at  the  surface  of  contact,  a  rose,  purple,  violet,  or  blackish  brown 
colour,  according  to  the  quantity  of  nitrate  present;  the  merest  traces  of 
the  latter  are,  however,  suflicient  to  produce  a  red  tinge.    (Desbassins  de 
Richemont,  J,  Chim,  Med,  II,  11,507;  Wackenroder,  Ann.  Pharm,  18, 
158.)     The  solution  of  a  nitrate  mixed  with  oil  of  vitriol  and  a  small 
quantity  of  tincture  of  sulphate  of  indigo,  changes  the  blue  colour  of  the 
latter  to  yellow.     This  effect  is  produced  when  the  nitric  acid  amounts  to 
no  more  than  ^^  of  the  solution ;  and  if  common  salt  be  added,  7^  of 
nitric  acid  is  sufficient  to  produce  it  (Liebig,  Schw,  49,  257.)     A  strip  of 
paper  moistened  with  the  indigo  solution,  may  also  be  held  in  the  mouth 
of  the  tube  in  which  the  mixture  of  nitrate  and  oil  of  vitriol  is  heated. 
(Chlorates  and  other  salts  of  similar  composition  likewise  decolorize  indigo 
under  these  circumstances.     An  aqueous  solution  of  a  nitrate  mixed  with 
tincture  of  litmus  and  then  with  oU  of  vitriol,  reddens  the  litmus  without 
discharging  its  colour,  unless  a  metallic  chloride  is  present  in  considerable 
quantity  (this  character  distinguishes  the  nitrates  from  the  chlorates). 
( Vogel,'  Jun.  J.  pr.  Chem.  23,  507.)     When  oil  of  vitriol  (3  ^ammes)  is 
mixed  with  a  few  drops  of  the  solution  of  a  nitrate,  and  the  liquid  stirred 
up  with  a  small  quantity  of  powdered  brucine,  a  blood-red  colour  is  pro- 
duced, gradually  changing  mto  yellow  ;  in  this  manner,  1  part  of  nitric 
acid  may  be  detected  in  10,000  parts  of  a  solution.     Narcotine  forms  an 
equally  delicate  test,  but  the  yellow  colour  precedes  the  red,  which  latter 
is  more  permanent.  (Berthemot,  J.  Pharm,  27,  560.)     When  a  powdered 
nitrate  is  introduced  into  the  solution  of  a  few  grains  of  narcotine  in  10 
drops  of  oil  of  vitriol,  the  salt  becomes  surrounded  with  a  red  ring ;  but  chlo- 
rates and  similar  salts  give  the  same  red  colour.  (Mialhe,*/*.  Pharm,  22,585.) 
VOL.  II.  2d. 


402  NITROGEN. 

All  nitrates  excepting  those  which  are  basiC|  lire  soluble  in  water. 

/.  With  certain  organic  substances. 

Fuming  NUric  acid,  Nitrou$  acid,  Salpetrige  Salpetertaure. 
Spirittu  nitri  fumans, — Properly  speaking,  a  mixture  of  nitric  acid  con- 
taining but  a  small  quantity  of  water  with  hjponitric  acid.  Formed  by 
mixing  h3rponitric  acid  with  concentrated  nitric  acid,  or  by  passing  nitnc 
oxide  gas  through  the  latter.  According  to  Mitscherlich,  (Pogg.  18,  157) 
2  parts  of  monohydrated  nitric  acid  dissolye  1  part  of  hjponitric 
acid.  It  is  obtained  in  the  concentrated  state,  by  distilling  2  parts 
(2  atoms)  of  nitre  with  1  part  (1  atom)  of  oil  of  yitriol,  or  with 
a  rather  larger  (quantity  of  fuming  oil  of  yitriol;  also,  according  to 
Mitscherlich,  by  distilling  nitre  with  bisulphate  of  potassa.  When  2  atoms 
of  nitre  and  1  atom  of  oil  of  yitriol  are  distilled  together,  half  the  nitric 
acid  passes  oyer  first,  in  the  form  of  hydrate ;  afterwards  the  other  half, 
at  a  temperature  nearly  approaching  to  redness,  and  for  the  most  part, 
decomposed  into  oxygen  gas  and  hyponitric  acid  yapour.  The  latter  is 
absorbed  by  the  nitric  acid  in  the  receiyer,  while  the  oxygen  escapes  (see 
page  391).  If  the  apparatus  were  tightly  connected  an  explosion  would 
ensue. 

Yellowish  red  liquid,  emitting  fumes  of  the  yellowish  red  colour  of  hy- 
ponitric acid  but  darker;  specific  grayity  =  1*536;  solidifies  at  —  49^ 
{--56°  F.)  to  a  yery  dark  red  mass. 

When  it  is  partially  distilled  and  the  product  collected  in  a  receiyer 
surrounded  with  a  freezing  mixture,  two  strata  of  liquid  condense  in  the 
receiyer;  the  upper  of  these  is  hyponitric  acid;  tne  lower,  unaltered 
fuming  nitric  acid;  they  do  not  mix  when  shaken  up  together.  (Mits- 
cherlich, Pogg.  15,  618.)  A  small  quantity  of  water  changes  the  colour 
of  fuming  nitric  acid  to  oliye  green,  and  causes  an  eyolution  of  nitric 
oxide  gas;  a  larger  quantity  changes  it  to  pale  blue;  and  a  still  further 
addition,  renders  it  oolourless.  On  the  addition  of  oil  of  yitriol  to  the 
colourless  liquid,  these  colours  re-appear  (according  to  Gay-Lussac,)  in 
the  reverse  order.  An  alkali  added  to  fuming  nitric  acid  forms  a  nitrate, 
and  probably  also  a  nitrite,  with  eyolution  of  nitric  oxide  gas.  The 
fuming^acid  has  a  much  stronger  tendency  to  giye  up  oxygen  to  other 
substances,  with  disengagement  of  heat  and  light,  than  pure  nitric  acid  of 
an  equal^degree  of  oonoentration. 

APPENDIX. 
Atmospheric  Am. 

Since  atmospheric  air — for  reasons  already  giyen  (I.,  20, 22)  must  be 
regarded  merely  as  a  mixture  of  oxygen,  nitrogen,  and  other  gases,  and 
not  as  a  chemical  compound,  its  examination  belongs  rather  to  Mete- 
orology and  Analytical  Chemistry  (since  mixtures  of  elastic  fluids  can  be 
separated  only  by  chemical  means)  than  to  Pure  (Themistzy, 

Properties,  Colourless.  One  litre  of  air  free  from  aqueous  yapour 
and  carbonic  acid,  weighs  at  0°  C.  and  0*76"  Bar.,  1*2991  grm.  accoraing 
to  Biot  &  Arago,  and  1  '2995  grm.  according  to  Dumas  &  ^oussingault.* 
Now  as  1  litre  of  water  at  -|-4°  (the  point  of  its  greatest  density) 
weighs  1000  grammes,  atmospheric  air  at  a  temperature  of  0°  and  under 
a  pressure  of  0*76  met  must  be  770  times  lighter  than  water  at  +4"" 

*  100  cubic  inches  of  air  at  32^  F.  and  29*92  fiar.  weigh  32*58864  grains;  at 
60"*  P.,  30*82926  gr.  Begnauit.  (Vid.  QrahanC$  Chemutry,  New  Ed.  p.  824.) 


ATMCNSPHEBIC  AIR.  403 

(fFul./L)  281.)  In  the  tnafis,  it  probably  baa  a  blae  oolour;  it  is  tasteless 
and  inodorous ;  adapted  for  respiration  and  a  supporter  of  combustion. 

Compodtion.  Tbe  air  is  a  mixture  of  nitrogen  eas  and  oxygen 
gases  in  almost  inTariable  proportions;  small  and  variable  quantities  of 
carbonic  acid  gas  and  aqueous  vapour  are  also  present;  and  sometimes 
also  certain  other  substances^  organic  and  inorganic. 

Nitrogen  and  Oxygen  gase$.  That  department  of  analytical  chemif  try 
"which  teaches  the  mode  of  estimating  the  oxygen  present  in  the  air,  is 
called  Eudiometry  {LvftguteprufungB-Lehre), — because  it  was  at  one  time 
erroneously  supposed  that  the  salubrity  of  tbe  air  depends  upon  the 
amount  of  oxygen  which  it  contains.  Instruments  for  determining  the 
quantity  of  oxygen  in  the  air  are  called  JSndiametert  {LuftgiitemetBer. )  In 
these  instruments,  the  air  is,  by  means  of  various  substances,  deprived  of 
its  oxygen  ;  and  from  the  diminution  of  volume  thus  effected  or  from  the 
loss  of  weight  sustained,  the  proportion  between  the  nitrogen  and  oxygen 
gases  is  calculated. 

1.  Eudiometer  ofJDumas  ^  BoumngauU. — A  small  glass  globe  is  ex- 
hausted by  the  air-pump,  weighed,  and  screwed  on  to  a  glass  tube  like- 
wise weighed  and  exhausted  of  air,  and  containing  copper  reduced  from 
the  oxide  by  hydrogen  gas.  The  tube  is  then  heated  to  redness,  and 
the  stopcock  attached  to  the  outer  end  of  it  opened,  so  that  the  external 
air  (previously  passed  over  hydrate  of  potash  and  oil  of  vitriol  to  free  it 
from  carbonic  acid  and  water)  may  enter.  Upon  this,  the  other  stop- 
cock attached  to  the  tube  is  opened  and  also  that  of  the  glass  globe  :  the 
nitrogen  of  the  air  then  rapidly  enters  the  globe,  while  the  oxygen  is 
completely  absorbed  by  tbe  ignited  copper.  The  three  stopcocks  are  then 
dosed,  tlie  tube  unscrewed  from  the  glass  globe,  and  both  globe  and  tube 
weighed,— after  which  they  are  again  ezbausted  and  reweighed.  The 
difference  in  weight  of  the  tube  and  globe  before  and  after  exhaustion 
gives  the  quantity  of  nitrogen  gas;  the  increase  in  weight  of  the  tube, 
from  the  oxidiation  of  the  copper  contained  in  it  gives  the  amount  of  oxy- 
gen which  was  mixed  with  the  nitrogen.  (Dumas  &  Boussingault,  Compt. 
Bend.  12,  1005;  also  Ann,  Chim.  Phys.  78,  257;  also  Pogg.  53,  391.) 

2.  Brunner's  Eudiometer. — A  tube  3  feet  long  is  half  filled  with 
slaked  lime  and  half  with  asbestos  moistened  with  oil  of  vitriol,  to 
remove  the  carbonic  acid  and  moisture  from  the  air  which  passes  through; 
one  end  of  the  tube  is  open  for  the  admission  of  air;  the  other  is  con- 
nected with  a  second  tube.  The  latter  where  it  enters  the  first  tube  is 
narrow,  and  then  increases  to  4^  lines  in  width  for  a  space  of  4  inches, — 
beyond  which  is  another  narrow  part  about  6  inches  in  length.  This 
end  and  half  of  the  broad  part  of  the  tube  adjoining  it  is  filled  with 
carded  cotton  wool  freed  from  all  moisture  by  warming  and  exhaustion. 
Into  the  other  half  of  the  broad  part  of  the  tube  adjoining  tbe  first 
tube,  a  gramme  of  perfectly  dry  phosphorus  is  introduced,  together  with 
some  asbestos,  for  the  purpose  of  diffusing  the  current  of  air,  so  that  every 
part  of  it  may  come  in  contact  with  the  phosphorus.  The  phosphorus  is 
then  heated  till  it  fuses,  and  spread  over  the  surfiace  of  the  tube  by 
turning  the  latter  about.  This  tube  is  then  connected  on  its  phosphorus 
side  with  the  first  tube,  and  on  the  cotton-wool  side  with  an  aspirator 
containing  oil ;  the  phosphorus  is  heated  till  it  liquefies,  and  about  4ox.  of 
oil  are  allowed  to  escape  from  the  aspirator.  In  this  manner,  the  cotton 
wool  becomes  saturated  with  phosphorous  acid,  the  use  of  which  is  to 
remove  every  trace  of  oxygen  from  the  air  in  the  subsequent  experiment. 
The  aspirator  is  then  closed;  the  second  tube  weighed,  and  again  con- 

2  D  2 


404  NITROGEN. 

nected  with  tbe  first  tube  and  the  aspirator;  and  the  experiment  pro- 


volume  of  the  oil  which  runs  out  gives  directly  the  volume  of  the  nitro- 
gen which  enters  the  aspirator;  the  increase  in  weight  of  the  second  tube 
shofTS  the  weight  of  the  oxygen  absorbed  by  the  phosphorus ;  and  from 
the  weight,  the  volume  of  that  element  is  calculated.  In  his  first  expe- 
riments, Brunner  employed  heated  iron  instead  of  phosphorus.  (Brunnery 
Fogg.  27,  1;  31, 1;  also  Ann.  Chim.  Phys.  78,  305.) 

3.  JSausmre's  Eudiometer, — Into  a  globe  of  the  capacity  of  about  200 
cubic  centimetres,  and  fitted  with  a  metallic  screw,  leaden  shot  (about 
80  or  100  to  the  gramme)  moistened  with  about  -^j  of  their  weight  of 
water,  are  introduced.  The  whole  is  then  shaken  with  the  enclosed 
atmospheric  air,  for  a  space  of  three  hours,  till  the  yellow  oxide  of  lead 
first  formed  becomes  grey  from  admixture  of  metallic  lead.  The  globe 
is  then  brought  to  its  original  temperature,  and  opened  under  water : 
the  volume  of  the  water  which  enters  gives  the  volume  of  the  oxygen 
and  also  of  the  carbonic  acid  absorbed;  that  of  the  nitrogen  is  obtained 
by  direct  measurement.  (Saussure,  J^.  BiJbl.  Univere,  2,  170;  also  Pogg, 
38,  171;  Ann,  Pharm,  19,  51.) 

4.  Gay-Luemc^e  Eudiometer, — Into  the  atmospheric  air  to  be  examined, 
a  copper  plate  moistened  with  dilute  sulphuric  acid  is  introduced, — ^which 
if  the  acid  is  from  time  to  time  renewed,  absorbs  the  whole  of  the  oxygen 
gas  in  the  course  of  a  few  hours.  (Gay-Lussac,  J  nn.  Chim,  PhyB,  62,  219.) 

5.  Eudiometer  of  Berihollet,  Parrot, — The  oxygen  is  removed  from 
a  known  volume  of  air  contained  in  a  vessel,  by  allowing  phosphorus  to 
bum  slowly  in  it,  till  the  phosphorus  ceases  to  emit  vapour  and  no  longer 
appears  luminous  in  the  dark.  The  residual  gas  is  nitrogen.  (BerthoUet, 
J,  Polytechn,  3,  274;  also  Scher,  J,  4,  588;  Parrot,  GUb.  10, 198;  Bock- 
mann,  Gilh.  11,  61.) — BerthoUet  (Statique  Ckem.  1,  514)  supposed  that 
the  residual  nitrogen  gas  expands  by  ^^  of  its  volume,  from  absorption  of 
phosphorus ;  and  consequently  that  this  amount  ought  to  be  subtracted 
from  the  observed  volume;  but  according  to  Brunner  {Pogg.  31,  2)  the 
quantity  of  vapour  evolved  by  phosphorus  at  ordinary  temperatures 
is  too  small  to  cause  any  perceptible  expansion  of  the  nitrogen.  If  a 
gaseous  mixture  to  be  tested  for  oxygen,  contains  any  of  those  gases  or 
vapours  which  prevent  the  slow  combustion  of  phosphorus  (p.  116)  this 
method  is  inapplicable.  (Graham,  Schw,  57,  235.)  The  presence  of 
aqueous  solution  of  potash  (which  may  have  been  used  to  remove  car- 
bonic acid)  also  interferes  with  the  action ;  because  the  potash,  by  contact 
with  the  phosphorus,  disengages  phosphuretted  hydrogen  gas.  (Viola, 
J.  Pharm,  13,  102.) 

6.  Eudiometer  of  Adiard,  Peboul,  and  Segiiin, — Atmospheric  air 
enclosed  in  a  vessel  is  robbed  of  its  oxygen  by  phosphorus  in  a  state 
of  rapid  combustion :  thus,  a  piece  of  phosphorus  is  introduced  into  an 
inverted  glass  tube  filled  with  mercurj^ ;  and  while  the  phosphorus  is  heated 
by  a  live  coal  held  near  the  tube,  a  measured  quantity  of  atmospheric 
air  is  suffered  to  enter  the  tube  in  separate  bubbles ;  the  tube  is  then  left 
to  cool,  and  the  volume  of  the  residual  nitrogen  is  read  off.  Any  apparatus 
in  which  the  burning  phosphorus  comes  in  contact  with  the  whole  of  the 
air  at  once,  is  very  apt  to  break.  (Achard*s  Physik.  Chem,  Ahhandl. 
1,  327;  Reboul,  Ann.  Chim,  13,  38;  Seguin, -4 nn.  Chim.  9,  293;  also 
CrelLAnn.  1794,  2,  453;  Bischof,  Schw.  37,  168.) 


ATMOSPHERIC  AIR.  405 

7.  Eudiometer  of  Scheele  and  De  Marty, — The  oxygen  gas  ier  remov^ed 
from  atmospheric  air  hv  agitating  it  for  a  quarter  or  half  an  hour^  with 
an  aqueous  solution  of  monosulphide  or  poljsulphide  of  potassium,  or 
pentasulphide  of  calcium  (obtained  by  boiling  sulphur  with  lime  and 
water).  The  solution  must  be  prepared  cold;  or,  if  heat  is  applied  in 
its  preparation,^— whereby  the  nitrogen  gas  absorbed  from  the  air  is  ex- 
pelled— it  must  be  shaken  up  when  cold  with  atmospheric  air,  in  order 

resaturate  it  with  nitrogen;  if  this  precaution  be  not  taken,  the  liquid 
will  absorb  nitrogen  from  the  air  to  be  analyzed.  The  diminution  of 
volume  gives  the  exact  amount  of  oxygen.  (Scheele,  on  Air  and  FirCy 
64;  De  Marty,  Scker.  J,  8.  63;  also  GUb.  19,  389;  N.  GehL  4,  146;  and 
Gilb,  28,  422;  Guyton  Morveau,  J.  Polytechn.  2,  166;  Von  Humboldt 
&  Gay-Lussac,  Gilb.  20,  42;  Hope,  Gilh.  19,  385.) 

8.  VoUa'a  Eudiometer, — To  a  measured  quantity  of  atmospheric  air 
contained  in  a  detonating  tube  standing  over  water  or  mercury,  a  mea« 
sured  quantity  of  pure  hydrogen  gas  is  added  (amounting  to  at  least 
half  and  not  exceeding  the  whole  volume  of  the  air,)  and  the  mixture 
exploded  by  the  electric  spark.  The  gaseous  residue,  consisting  of  the 
whole  of  the  nitrogen  and  the  excess  of  hydrogen,  is  then  measured,  and 
its  volume  deducted  from  the  original  volume  of  the  air  +  that  of  the 
hydrogen  gas  before  explosion;  the  difference  divided  by  3  gives  the 
volume  of  oxygen  that  was  present  in  the  air  under  examination.  (  Volta, 
Brugnat,  Annali  di  Chimica,  1,  171;  2,  161;  3,  36;  Humboldt  <fc  Gay- 
Lussac,  A.  Gehl.  5,  45;  also  Gilb:  20,  38:  A.  BerthoUet,  Gilb,  34,  452: 
Gay-Lussac,  Ann,  Ghim,  Pkys,  66,  443;  also  J,  pr,  Ohem,  14,  61.) 
Instead  of  emplojring  the  electric  spark,  the  mixture  of  atmospheric  air 
and  hydrogen  may  be  inflamed  by  a  platinum  wire  wound  into  a  coil 
and  heated  to  reaness  by  a  galvanic  battery.  (Grove,  Phil,  Mag,  J, 
19,  99.)  The  mixture  may  also  be  made  to  combine  slowly  by  means 
of  finely  divided  platinum;  this  method  is  best  adapted  for  gaseous  mix- 
tures containing  extremely  small  quantities  of  oxygen,  and  therefore 
not  capable  of  being  exploded  by  the  electric  spark.  It  has  also  the 
advantage  of  not  condensing  any  nitrogen  gas  in  the  form  of  am- 
monia, which  is  the  case  when  the  mixture  is  exploded.  For  this 
purpose,  balls  made  of  platinum  and  clay  (p.  49),  introduced  into  the 
mixture  on  a  platinum  wire  answer  very  well ;  or  spongy  platinum  placed 
in  a  small  inverted  capsule  and  introduced  by  means  of  a  platinum  wire, 
so  that  it  may  not  get  wet ;  or  the  measured  mixture  of  gases  may  be 
introduced  into  a  tube,  the  surface  of  which  is  covered  with  finely  di- 
vided platinum.  (Dobereiner,  Gilb,  74,  272;  Schw,  47,  122;  Kastn.Arck, 
9,  341;  J,  pr  Ghem.  15,  284;  Pleischl,  Schw.  39,  150  &  204;  Turner, 
Ed.  Phil,  J.  11,  99;  also  Pogg,  2,  210;  Degen,  Pogg,  27,  557.) 

9.  Fontana' 8  Eudiometer. — First  used  byPriestley.— 100  measures  of 
atmospheric  air  contained  in  a  graduated  tube  standing  over  water  are 
mixed  with  100  measures  of  nitric  oxide,  and  the  diminution  of  volume 
observed.  Out  of  200  measures  of  the  mixture,  between  80  and  90  mea- 
sures generally  disappear.  It  must  be  observed,  however,  that  nitric  oxide 
is  capable  of  uniting  with  oxygen  in  different  proportions,  inasmuch  as  4 
measures  of  nitric  oxide  with  1  measure  of  oxygen  form  nitrous  acid; 
with  2  measures,  hyponitric  acid;  and  with  3  measures,  nitric  acid. 
Moreover,  one  or  other  of  these  compounds  will  predominate,  accordingly 
as  the  excess  of  the  nitric  oxide  over  the  oxygen  is  greater  or  smaller — 
or  as  the  atmospheric  air  or  the  nitric  oxide  enters  first  into  the  tube — or 
according  to  the  rapidity  with  which  the  two  gases  are  mixed — the  width 


406  NITROGEN. 

of  the  tube — the  agitation  or  quiesoenoe  of  the  mixtnie-^the  temperatare, 
&c.^  &o.  Conseqaently^  this  form  of  eudiometer,  notwithstanding  the 
improYements  that  have  been  made  in  it,  is  the  least  accurate  of  all;  and, 
in  former  years,  when  it  was  used  in  preference  to  all  others,  gave  rise  to 
yery  inaccurate  statements  respecting  the  amount  of  oxygen  contained 
in  the  air,  which  was  said  to  vary  considerably  according  to  the  direction 
of  the  wind,  the  season  of  the  year,  the  salubrity  of  the  atmosphere,  &o. 
According  to  Scherer,  f  of  the  diminution  of  volume  should  be  regarded 
as  oxygen  gas;  according  to  Ingenhouss,  4f ;  according  to  Gkky-Lussac^ 
i,  provided  the  mixture  is  contained  in  a  large  vessel  and  not  shaken ; 
according  to  Von  Humboldt,  ^;  according  to  Lavoisier,  from  ^ff  to  ||^f ; 
according  to  Priestley,  ^^;  according  to  Hildebrandt,  \;  and  according 
to  Dalton,  from  |^^  to  ^Jff-  (^*^-  Montana,  Descrizume  edundi  alcuni 
Hrumenli  per  miiurare  la  talvbrttd  dell*  aria.  Firenze,  1770  : — Ingenhouss, 
Crell.  Chem.  J.  1,  215  :— Lavoisier,  OreU.  Ann.  1788,  2,  426  :— Cavendish, 
An  Account  of  a  New  EvdiomeCer,  Lend.  1783;  also  PhU.  Transact. 
1783: — Von  Humboldt,  Versuch  einer  ZerUgung  de$  Lufthreisa;  also 
Scher.  J.  1,  263;  3,  88  &  146:— Dalton,  OUh.  27,  36d  :--Gay-Lus8ac, 
N.  GehZ.  9,  445 ;  also  0^1.  36,  37.) 

10.  Sir  H.  Davy's  Evdiometer. — A  solution  of  ferrous  sulphate  sa- 
turated with  nitric  oxide  gas  serves  for  the  absorption  of  oxygen  gas ; 
but  as  a  portion  of  nitric  oxide  from  the  solution  readily  mixes  with 
the  residual  nitrogen  gas,  the  former  must  be  removed  by  agitation  with 
a  pure  solution  of  ferrous  sulphate.  (H.  Davy,  OUh.  19,  394.)  As  the 
liquid  also  evolves  a  small  quantity  of  nitrogen,  proceeding  from  the  d^ 
composition  of  the  nitric  oxide,  this  method  gives  the  proportion  of 
nitrogen  too  high.  (Berzellus.) 

(On  Eudiometers  in  general,  vid.  Dalton,  PhU.  Mag.  J.  1358 ;  also  Reg- 
t  &  Reiset,  N.  Ann.  Ohim.  Phys.  26,  299.] 

In  those  methods  which  require  a  considerable  lapse  of  time,  so  that 
the  temperature  and  atmospheric  pressure  may  vary  during  their  perform* 
ance,  the  necessary  corrections  must  be  made. 

From  the  experiments  of  Dumas  &  Boussiuffault,  Brunner,  and  other 
chemists,  it  may  be  considered  as  established  that  atmospheric  air  freed 
from  carbonic  acid  and  aqueous  vapour  contains  in  100  parts  by  weight, 
23  parts  of  oxygen  and  77  parts  of  nitrogen, — and  in  100  volumes,  20*8 
volumes  of  oxygen  sas  and  79*2  volumes  of  nitrogen  gas;  and  that 
these  proportions  undergo  but  very  little  variation,  never  amounting 
to  1  per  cent.  Differences  of  years,  seasons,  winds,  weather,  loca- 
lity, and  height  and  salubrity  of  the  atmosphere,  have  little  or  no  in- 
fluence. A  great  part  of  the  variations  obtained  by  individual  chemists 
may  be  attributed  to  the  use  of  defective  methods,  or  to  errors  of  obser- 
vation. 

H  From  the  late  experiments  of  Regnault  &  Reiset  (at  Paris),  it 
appears  that  100  volumes  of  air  contain,  on  the  average,  20-96  volumes 
of  oxygen  gas.  {Oompt.  Rend.  26,  4;  also  Ann.  Pharm.  68,  221.)   IT 

Dumas  &  Boussingault  (Compt  Mend.  12,  1005;  also^nn.  Chim.  Phys. 
78,  257;  also  Ann.  Chim.  Phys.  78,  291),  found,  in  the  year  1841,  in  100 
parts  by  weight  of  air  taken  from  the  Jardiu  des  Plantes  at  Paris,  and 
freed  from  aqueous  vapour  and  carbonic  acid,  the  following  proportions  of 
oxygen ;  annexed,  are  a.so  the  quantities  of  oxygen  found  on  the  same 
days  by  Brunner  in  the  air  at  Bern,  and  by  Martins  &  Bravais  in  the  air 
on  the  FaulhorU;  2683  metres  or  8803  feet  above  the  sea-level : 


Tempera- 

ture. 

Wind. 

Weather. 

Paris. 

Bern.  Panlhom. 

I.  23*'    .. 

.  S  

....  Pine 

..  22-92 

,    26«    .. 

.  SE    .... 

....  Pine 

..  2306 

,    27«    .. 

.  NB  .... 

....  Pine 

.  23-03 

,    17-4«.. 

.  N     .... 

....  Rain 

..  23-01 

,    19^     ... 

.  s  

....  Rain     .. 

..  2300  .. 
..  2300  .. 

..  23*00  ....  22-96 

.    U'7\. 

.  SW  .... 

....  Pine 

..  22-89  ....  2309 

,    17-8V.. 

.  NNW 

....  Cloudy.. 

..  23-08  .. 

..  22-97  ....  22-91 

,   22-6»... 

.  N 

....  Pine 

..  2307 

7  Angnst  22-97 

,    21»    .... 

8SW    . 

...  Cloudy  .. 

.  22-89 

ATMOSPHERIC  AIR.  407 

Baro- 
meter. 
27  April 0-7595M, 

28 0-7583 

29 0-7676 

29  May   0-7679 

20  July   0-7339 

21 0-7520 

24 0-7582 

20  September ....  0-7589 
22  ....  0-7612 

Mean  of  the  quantity  of  oxygen  in  100  parts  by  weight  of  air  23*07 

Verver  found  in  the  air  at  Oroningen  22*998  parts  bj  weight  of  oxygen ; 
— *Marignao  (Campt  Rend,  14,  379),  in  that  of  Geneya,  22*98  parts; — 
Levy  found  in  the  land  air  at  Copenhagen  22*998  parts;  in  the  sea  air 
taken  iust  abore  the  surface  of  the  sea,  22,575  parts;  in  the  sea  air,  35 
feet  above  the  level  of  the  sea,  23*016  parts;  so  that  the  air  near  the 
sur&ce  of  the  sea  is  poorer  in  oxygen. — Stas  {Oompt,  Bend.  14,  570)  ob- 
tained (at  Brussels?)  in  12  experiments,  from  23*04  to  23*08  parts;  but 
in  an  experiment  performed  at  a  different  time  with  an  equal  degree  of 
care^  2311,  and  in  another,  23*14  parts  of  oxygen. 

Berthollet  (Oilb.  5,  349)  found  in  100  measures  of  atmospheric  air,  at 
Cairo  and  at  Paris,  nearly  22  measures  of  oxygen  gas  ;— Saussure  found 
at  Geneva  {GU6.  1,  508)  from  21  to  22  measures,  and  in  his  more  recent 
experiments  with  eudiometer  (3),  20*6  measures; — De  Marty  (Oilb.  19, 
389)  found  in  the  air  in  Catalonia,  with  every  kind  of  wind  and  weather, 
under  various  degrees  of  atmospheric  pressure,  and  at  every  season  of  the 
year,  also  over  morasses  and  stagnant  pools,  and  in  places  where  large 
assemblies  of  people  were  collected— from  21  to  somewhat  less  than  22 
measures ;  Sir  li.  Davy  (Gilb.  1 9, 394)  found  in  the  air  at  Bristol  and  other 
parts  of  England,  also  in  air  taken  from  over  the  sea  on  the  west  coast  of 
England  during  a  west  wind,  and  in  air  brought  from  the  coast  of  Guinea, 

21  measures  of  oxygen  gas; — Berber  (Gilb.  19,  412)  found  the  air  on  the 
Jura,  on  the  mountains  and  in  tne  valleys  of  Savoy,  on  the  glaciers  in 
that  locality,  and  in  the  Valais,  to  contain  from  20*3  to  21*65  measures ; 
— Configliachi  (Schw,  1,  144),  found  on  the  Simplon,  Mount  Cenis,  and 
other  mountains  of  the  Alps,  21 ;  over  swampy  meadows,  21;  over  rice- 
fields,  20*8  ;  and  in  close  places,  20*3  volumes ; — Gay-Lussao  &  Von 
Humboldt  at  Paris,  in  every  kind  of  weather  and  season  of  the  year, 
found  from  20*9  to  21*1  volumes;  Gay-Lussac  {Gilb,  20,  33),  ,6636 
metres  or  21,772  feet  above  the  surface  of  the  earth,  and  likewise  ii| 
Paris,  21*49  volumes ; — A.  Vogel  &  Kriicer  {Gilb,  66,  94),  over  the  Bal* 
tic  Sea^  20*59  volumes; — Hermbstadt  (Sdiw.  32, 281)  found  in  the  month 
of  April,  on  the  shore  of  the  Baltic,  5  leet  above  the  sea-level,  21*5 ;  and 
at  16  feet  above,  20*5  volumes,  while  the  air  over  the  land  contained 
20  volumes  of  oxygen  (from  which  he  concludes  that  sea- water  gives 
off  oxygen  gas); — Dalton  {Ann,  Phil.  26,  304)  found  in  England, 
generally  from  20*7  to  20*8,  more  rarely  21;  and  on  the  8th  of  January, 
1825,  at  30*9  in.  atmospheric  pressure,  and  with  a  north-east  wind,  the 
maximum,  viz.,  21*15  volumes.  From  the  following  more  recent  obser- 
yations,  in  which  atmospheric  air,  taken  at  the  same  time  from  an  elevated 
and  a  low  locality,  was  examined,  Dalton  {Phil,  Mag.  J.  12,  397)  con- 
cludes that  the  air  in  elevated  regions  contains  rather  less  oxygen  gas 
than  that  nearer  the  leyel  of  the  sea.     From  the  constant  intermixture 


408  NITROGEN. 

however  of  tlie  air  by  winds,  &c.,  the  difference  in  amount  of  oxygen 
cannot  be  bo  great  as  it  should  be  in  accordance  with  his  theory  (I.  22,  2). 
Air  from  Helvellyn  (3000  feet  high),  contained  2064  volumes; 
from  Manchester,  20*99  rolumes  of  oxygen  gas ;  also  from  Helvellyn, 
20-63 ;  from  Manchester,  20*73 ;  air  from  Snowdon  (3570  feet  high),  20-70; 
from  the  level  country  three  English  miles  from  Manchester,  20*85; 
air  collected  by  Grafton  in  a  balloon  9600  feet  above  the  level 
of  the  sea,  20'70;  from  Manchester,  20*83.  Air  collected  by  Green 
in  a  balloon  15,000  feet  high,  20*62;  from  Manchester,  20*95;  air  from 
the  Mer  de  Glace  near  Chamounix,  6000  feet  high,  19*80;  from  the 
Simplon,  6174  feet  in  height,  19*76;  from  the  Wengem  Alp,  6230  feet 
high,  20*28  volumes.— Th.  Thomson  {J.  pr.  Chem,  8,  365)  found  in  the 
air  at  Glasgow,  as  a  mean  of  a  great  many  experiments,  21*01  volumes 
of  oxygen  gas ; — Kupffer  {Sckw,  67,  214)  found  in  the  air  at  Kasan  from 
21  to  21*2  volumes ; — Brunner  {Pogg.  31,  7,)  found  in  Switzerland  during 
the  month  of  July,  in  the  open  country,  21*0705,  and  according  to  his 
more  recent  experiments  (Ann.  Chim.  Phys.  78,  305),  20*85  volumes; 
on  the  Faulhom,  20*915  volumes. — Boussingault,  {Ann.  Chim,  Phys.  76, 
360)  found  at  Mariquita,  548  metres  or  1799  feet  above  the  sea-level 
in  November,  20*77 ;  at  Ibaque,  1323  metres  or  4341  feet  high,  in  Decem- 
ber, 20-7;  and  at  Santa  Fe  de  Bogota,  2643  metres  or  8671  feet  high, 
during  April,  20*65  volumes. — Air  taken  by  Green,  by  means  of  his  bal- 
loon, at  an  elevation  of  1 1 ,300  feet,  contained  21  volumes. — Baumgartner 
(Medic.  Jahrb.  d.  osier  Staats,  12,  83),  in  Vienna,  during  the  cnolerSy 
found  from  20*4  to  21*4  volumes  of  oxygon  gas  in  100  volumes  of  air. 

In  a  coalmine  on  the  Huhr,  Bischof  (iS'^tr,39, 285,)  found  22*93  volumes 
of  oxygen  gas,  whilst  the  air  on  the  outside  contained  only  21*35  volumes. 

In  the  air  which  escapes  from  iSssures  in  glaciers,  Bischof  (Schto.  37, 
266)  found  only  10*22  volumes  of  oxygen  gas  to  89*78  volumes  of 
nitrogen,  because  the  water  formed  from  the  melting  ice  absorbs  propor- 
tionaJly  more  oxygen  than  nitrogen  from  the  air  (p.  67).  In  the 
same  manner,  Saussure  and  Senebier  found  that  atmospheric  air  libe- 
rated from  the  snow  of  the  Alps  by  thawing,  was  poor  in  oxygen.  A 
similar  result  was  obtained  by  Boussingault  (Ann.  Chim.  PJiys.  76, 
354)  with  snow  from  the  Andes  and  from  Paris.  On  melting  the  snow  in 
an  inverted  bottle  completely  filled  with  it,  the  air  which  rose  to  the  top 
was  found  to  contain — that  from  the  Andes,  from  16  to  17  volumes,  and 
tbat  from  Paris,  18*7  volumes  of  oxygen;  the  resulting  snow-water,  when 
boiled,  yielded  bubbles  of  air  containing  32  volumes  of  oxygen  gas,  a 
proof  that  it  had  absorbed  the  oxygen  gas  in  preference  to  the  nitrogen 
of  the  air.  If  however  a  bottle  be  filled  with  snow,  and  the  air  which  it 
contains  pumped  out,  it  is  found  to  contain  from  20  to  21  volumes  of 
oxygen  gas.  If  the  snow  be  lightly  pressed  into  a  vessel,  the  air  con- 
tained in  the  vessel  after  the  liquefaction  of  the  snow  contains,  according 
to  Lampadius,  (J,  pr.  Chem.  10,  78)  19*71  volumes ;  but  if  the  snow  be 
closely  pressed  down,  only  18*91  volumes  of  oxygen  gas.  1000  of 
snow-water  obtained  from  snow  fallen  during  a  west  wind  yield,  when 
boiled,  33*31  volumes  of  atmospheric  air,  which  in  100  volumes  contain 
68*85  volumes  of  nitrogen  gas,  30*  12  of  oxygen,  and  10*3  volumes 
of  carbonic  acid  gas.  If  the  snow  be  closely  pressed  into  a  vessel,  and 
the  greater  part  of  the  air  removed  from  it  by  moistening  with  cold  boiled 
water,  the  resulting  snow-water,  when  boiled,  yields  only  -^  as  mueh  air, 
because  on  liquefying,  it  finds  but  a  small  quantity  of  air  to  absorb. 


/ 

I 


ATMOSPHERIC  AIR.  409 

Oarhonic  acid  gas.  Formerly  the  amount  of  carboDic  acid  in  the  air 
was  estimated  by  the  diminution  in  volume  observed  on  agitating  it  with 
aqueous  solution  of  ammonia^  potassa,  baryta,  or  lime,  in  Humboldt's 
A  nthracometer  for  example.  (Gilb.  3,  77.)  But  as  the  quantity  of  car- 
bonic acid  in  the  air  is  very  small,  the  results  obtained  oy  this  method 
were  inaccurate  and  the  amount  of  carbonic  acid  was  generally  estimated 
too  high. 

Thenard  introduces  a  small  quantity  of  baryta  water  into  atmospheric 
air  contained  in  a  glass  globe  of  the  capacity  of  10  litres  and  furnished 
with  a  stop  cock,  and  agitates  till  the  whole  of  the  carbonic  acid  is 
absorbed ;  he  then  exhausts  the  globe,  and  allows  a  second  quantity  of 
air  to  enter, — agitates  and  again  exhausts, — and  so  on,  till  the  baryta- 
water  has  been  treated  thirty  times  with  fresh  portions  of  air.  The 
weight  of  the  precipitated  carbonate  of  baryta  is  then  obtained,  and  from 
it  is  calculated  the  volume  of  carbonic  acid  gas  contained  in  the  volume 
of  air  employed.  Saussnre  (Ann.  Chim,  Phys,  2,  199;  also  Gilb,  54,  217; 
'—Ann,  Chim,  Phyg,  3,  170; — Ann,  Chim,  Phy%,  44,  5;  also  Bihl.  Univ. 
44,  23  &  138;  also  Schw,  60,  17  &  129;  also  Pogg,  19,  391)  at  first  em- 
ployed  a  method  similar  to  that  of  Th^nard's ;  subsequeutly  he  exhausted 
a  vessel  capable  of  holding  30  litres;  suffered  the  air  under  examination 
to  enter;  agitated  the  mixture;  poured  in  the  baryta- water;  and  de- 
termined the  amount  of  the  carbonate  of  baryta  thrown  down. 

Bruuner  {Pogg,  24,  569;  Ann,  Chim,  Phys,  78,  305),  by  means  of  an 

X&tor,  draws  the  air  to  be  examined,  first  through  a  tube  containing 
tos  moistened  with  oil  of  vitriol,  to  render  it  anhydrous,  and  then 
through  a  second  tube,  which  is  first  narrow  for  a  short  distftuce,  then 
wide  for  a  considerable  length,  and  then  narrow  for  a  still  greater  length. 
This  tube  contains  hydrate  of  lime  in  the  wide  part,  to  aosorb  the  car- 
bonic acid ;  and  in  the  long  narrow  portion,  asbestos  moistened  with  oil 
of  vitriol,  to  retain  the  water  which  the  air  reabsorbs  from  the  hydrate  of 
lime.  The  increase  in  weight  of  this  tube  gives  the  quantity  of  carbonic 
acid  contained  in  the  air  which  passes  through  it;  and  the  volume  of 
water  from  the  aspirator,  added  to  the  calculated  volume  of  the  carbonic 
acid  gas  obtained,  gives  the  original  volume  of  the  air  examined. 

According  to  the  experiments  of  Sanssure  and  Brunner,  which  agree, 
100  volumes  of  inland  air  may  be  regarded  as  containing,  on  an  average, 
0*05  vol.  of  carbonic  acid  gas. 

Saussure  examined  the  air  over  a  meadow  at  Chambeisy,  three-quarters 
of  a  mile  from  Geneva,  250  metres  from  the  Lake  of  Geneva,  16  metres  above 
the  lake,  and  388  metres  above  the  sea-level.  In  dry  months,  100  volumes 
of  air  contained  from  0*0479  to  0*0518  vol.  of  carbonic  acid  gas;  after 
long  rains,  from  0*0357  to  0*0456  vol. ;  in  December,  when  the  ground 
was  damp,  and  the  weather  cloudy,  from  0*0385  to  0*0425  vol. ;  in 
January,  during  a  frost,  0*0457  vol.;  at  the  end  of  .January,  with 
frequent  thaws ,  0*0427  vol.  Hence  it  appears  that  moisture  on  the 
ground  diminishes  the  amount  of  carbonic  acid  in  the  air  by  absorption ; 
frost  prevents  the  absorption.  The  air  over  the  Lake  of  Geneva  con-r 
tained  0*0439  vol.,  whilst  at  the  same  time  the  air  of  the  meadows 
contained  0*046  vol.  The  air  at  Geneva  contained  0*0468,  whilst 
that  from  the  meadow  contained  00457  vol.  The  air  on  the 
mountains  contained  more  carbonic  acid  than  that  of  the  meadows,  the 
difference  amounting  to  0  0557  vol.,  probably  because  the  air  in  the 
upper  regions  meets  with  fewer  plants  and  less  moist  ground,  by  which 
the  carl^nic  acid    [driven   upwards  by  the  processes  of  combustion] 


410  NITBOOBN, 

can  Ixe  fthiorbed.  The  quantity  of  oarbouic  aoid  in  the  air  during 
a  light  wind}  ia  to  the  quantity  dorinff  a  gale,  on  the  average, 
aa  0-0376  :0'0398|  becanae  a  strong  wind  mingles  the  higher  strata 
of  air  with  the  lower.  The  mean  proportion  of  carbonic  aoid  in 
summer  at  noon  is  to  that  at  ni^ht  as  0*0398  :  0*0432 ;  in  winter  the 
difference  is  less,  and  sometimes  disappears  entirely,  though  it  has  fre- 
quently been  found  to  exist  even  when  the  earth  has  been  covered  with 
snow,  at  a  temperature  below  0°.  The  maximum  quantity  of  carbonic 
acid  was  found  at  the  end  of  nighty  the  minimum  at  the  close  of  day. 
The  quantity  of  carbonic  acid  was  greatest  during  the  nights  as  compared 
with  the  days,  during  a  thaw,  with  the  temperature  much  lower  at  night 
than  in  the  day  time.  During  high  winds,  no  difference  was  observed 
between  the  quantity  of  carbonic  acid  b^  night  and  by  day.  (Saussnre.) 

Watson  (</.  pr.  Chetn,  6,  75)  found  in  100  volumes  of  air,  at  Bolton, 
a  mean  of  0*053  vol,  and  in  air  obtained,  at  a  distance  of  six  milee 
from  Bolton,  a  mean  of  0  04135  vol.  of  carbonic  acid;  and  less  when 
the  wind  blew  from  the  sea  than  when  it  blew  from  the  land. 

Dalton  estimated  the  amount  of  carbonic  acid  in  100  volumes  of  air 
at  0*065;  Configliachi,  at  0*08;  Von  Humboldt,  at  0*5 — 1*8  vol 

Carbonic  acid  gas  is  also  present  in  the  air  on  Mont  Blanc  (Saussnre), 
and  according  to  Beauvais  is  as  abundant  in  air  collected  by  means  of  a 
balloon  650  toises  above  Paris  as  in  the  air  of  Paris  itself. 

On  the  contrary,  the  air  over  the  sea  is  found  to  contain  sometimes  a 
much  smaller  quantity  of  carbonic  acid  and  sometimes  none  at  all.  The 
air  over  the  Baltic  at  Doberan,  and  over  the  North  Sea  at  Dieppe  con'* 
tains  scarcely  any  carbonic  acid.  (A.  Vogel.)  At  Rostock,  the  air  does 
not  render  lime  water  turbid  when  the  wind  blows  from  the  north  (the 
direction  of  the  Baltic) ;  but  that  effect  is  produced  when  the  south  wind 
blows  (which  comes  from  the  land).  (Kriiger,  Sckw,  35,  379.)  Emmet, 
however,  {Fhil.  Mag.  J.  11,  225)  found  carbonic  acid  in  the  sea-air 
throughout  his  whole  voyage  from  North  America  to  Bermuda ;  and  at 
Bermuda,  100  volumes  of  air  were  found  to  contain  0*0125  vol.  of 
carbonic  acid  gas. 

In  close  rooms,  in  which  the  oxygen  of  the  air  is  vitiated  and  car- 
bonic aoid  produced  by  the  processes  of  respiration  and  combustion,  the 
atmosphere  would  soon  become  uniit  to  breathe,  were  it  not  for  the  change 
of  air  which  takes  place  through  the  crevices  of  the  doors  and  windows, 
or  which  is  produced  by  artificial  ventilation.  (See  the  researches  of 
Leblanc,  Compt,  Rend.  14,  862.)  [On  the  air  in  the  mines  of  Cornwall, 
which  contains,  on  the  aversge,  82*848  volumes  of  nitrogen,  17*067 
volumes  of  oxygen,  and  0*085  vol.  of  carbonic  acid,  vid,  Hoyle, 
FhU.  Mag.  J.  19,  856.] 

Vap(mT  of  ITafer.— Estimated  either  by  the  Hygrometer  and  Fsyehro- 
meter  (I.,  274, 275,  and  289),  or  more  correctly  by  the  method  of  Brunner 
(Ann,  Chim.  Phy$.  78,  305),  in  which  the  air  is  drawn  by  means  of  an 
aspirator  through  a  tube  containing  asbestos  slightly  moistened  with  oil 
of  vitriol,  and  its  increase  in  weight  determined. 

The  quantity  of  aqueous  vapour  in  the  atmosphere  is  extremely 
variable,  and  is  greater  m  Germany,  during  southerly  and  westerly  winda 
in  summer  and  hot  weather,  than  during  northerly  and  easterly  winds  in 
winter  and  in  cold  weather. 

Oihtr  Inorganic  MaiterB  in  the  uitr.— These  must  be  regarded  as  aoei* 


ATMOSPHBBIC  AIR.  411 

dental  imparities,  eometimee  produced  by  atmospheric  electricity^  some- 
times  rising  in  the  form  of  vapoar  from  pecnliar  spots  on  the  earth's 
snr^Ebce,  or  carried  by  the  wind  in  the  form  of  dust  from  the  land  or  from 
the  sea  to  the  higher  regions  of  the  atmosphere.  They  are  chiefly  found 
in  lain  water,  especially  in  that  which  falls  after  a  long  drought.  The 
following  substances  have  been  thus  found : — Ilydrondphuric,  sulphuric, 
hydroMof'iCf  and  nitric  acids',  ammonia^  potash,  soda,  lime,  magnesia, 
iron,  manganese,  &c. 

Hydrosulphuric  add. — ^At  Amsterdam,  evolved  from  materials  con« 
taining  gypsum  used  for  burning ;  partly  converted  into  sulphuric  acid. 
( Von  Driessen  &  Veehof.)  Hydrosulphuric  acid  is  also  found  in  the  air 
over  sulphurous  springs,  and  over  particular  parts  of  the  sea  (see  p.  191.) 

SuJtphurous  acid  with  small  quantities  of  sulphuric  add, — Found  in 
the  air  of  London  (from  the  combustion  of  coal);  the  air  and  the  rain 
water  of  London  consequently  redden  litmus.  (Darcet,  Ghevallier,  J,  pr, 
Chem.  Med.  10,  292.) 

Hydrochlorie  add:  Found  on  the  coast  during  a  sea-breeze.  (A. 
Vogel,  GUb.  66,97;  72,  278;— Von  Driessen,  Schw.  36,  139.)— Roubaudi 
J.  Fharm.  19,  569;  21,  141)  filled  a  glass  globe  with  a  freezing  mixture, 
exposed  it  on  the  coast  at  Nizza,  from  6  to  50  paces  from  the  shore,  and 
examined  the  water  condensed  on  the  globe.  During  a  calm,  or  even 
with  a  rough  sea  and  no  wind,  it  behaved  like  distilled  water,  but  with  a 
boisterous  sea  and  a  searbreeze,  the  water  contained  hydrochloric  acid 
and  all  the  other  ingredients  of  sea-water.  The  same  results  were 
obtained  on  employing  Brunner's  aspirator.  Hydrochloric  acid  and  the 
other  components  of  sea-water  do  not  therefore  rise  in  vapour  from  the 
sea;  bat  the  sea- water  itself,  during  a  high  wind,  is  diffused  in  fine  par- 
ticles through  the  air.  Rain  or  snow  which  fell  at  Freiberg,  while  the 
air  was  tranquil,  and  after  a  previous  fall  of  rain  or  snow,  yielded  no 
residue  on  evaporation ;  that  wnich  fell  daring  a  strong  west  wind  con- 
tained salts,  especially  chloride  of  calcium.  (Lampadius,  J.  pr»  Chem. 
13,  244.)— Meissner,  {Schw.  36,  161)  did  not  find  any  hydrochloric  acid 
in  the  air  of  Halle  near  the  salt  works. — All  the  rain-water  which  fell 
at  Giessen,  at  77  different  times  during  a  period  of  two  years,  was  found 
to  contain  common  salt.  (Liebig,  Ann.  Chim.  Phys.  35,  320.) 

Nitric  add :  Appears  to  have  been  first  observed  by  Priestley.  Of 
the  above  mentioned  77  different  specimens  of  rain-water,  17  were 
obtained  during  thunder-storms ;  in  the  latter,  nitric  acid  was  found  com* 
bined  with  ammonia  and  lime ;  of  the  remaining  60,  two  only  contained 
a  trace  of  nitric  acid :  so  that  lightning  in  passing  through  the  air,  forms 
nitric  acid.  (Liebig.)  In  tropical  regions,  electrical  discharges  are  con*- 
stantly  taking  place  in  the  clouds ;  and  this  is  probably  the  origin  of  a 
ffreat  portion  of  the  nitric  acid  which  is  found  on  the  sur&ce  of  the  earth 
m  the  form  of  nitre.  Boussingault  {Ann.  Chim.  Phys.  57,  179)  and 
Lampadius  also  {J.  pr.  Chem.  14,  54)  found  that  rain-water  collected 
after  a  severe  thunder-storm  reddened  litmus  and  contained  0'3  grains 
of  nitric  acid  in  a  pound. 

Ammonia :  Probably  disengaged,  in  union  with  carbonic  or  other 
acids,  from  azotized  organic  matter  undergoing  the  process  of  putrefac- 
tion or  combustion.  Scheele  {Opusc.  2,  373)  found  that  ammoniacal  salts 
collected  round  the  mouths  of  bottles  containing  hydrochloric  or  sul- 
phuric acid,  when  kept  in  a  room. — Saussure  (A.  Qehl.  4,  691,)  observed 
that  sulphate  of  ^nmina  exposed  to  the  open  air,  was  converted 
into  ammoni»-alum.«— Dilute  sulphuric  acid  exposed  to  the  open  air  on  a 


412 


NITROGEN. 


roof  at  Paris,  was  foand  to  contain  ammonia.  ^CoUard  do  Martigu  j,  •/'. 
Chem.  Med.  3,  516.)~White  clay  heated  to  redness  and  then  exposed 
to  the  air  for  a  week,  yields  a  considerable  quantity  of  ammonia  when 
heated  a^in,  which  is  not  the  case  if  it  be  kept  in  a  close  vesscL  (Fara- 
day.)—Zimmermann  {Kastn.  Arch.  1,  257)  and  Brandes  {Schw.  48,  153.) 
found  a  trace  of  ammoniacal  salts  in  rain-water  evaporated  to  dryness. 
Zimmermann,  however,  attributed  the  ammonia  to  the  decomposition  of 
the  organic  matter,  by  heat. — Chevallier  {J.  Pharm.  20,  655)  often 
found  a  large  quantity  of  ammonia  in  the  air ;  at  Paris,  it  was  some- 
times combined  with  hydrosulphuric  acid  and  acetic  acid. — Rdn-water 
or  snow  collected  in  the  open  fields,  yields  a  distillate  which  contains 
carbonate  of  ammonia,  and,  when  evaporated  with  a  small  quantity  of 
hydrochloric  acid,  leaves  sal-ammoniac  having  a  yellow  or  brown  colour.  An 
ammoniacal  salt  is  likewise  obtained  when  rain-water  is  evaporated  with 
sulphuric  or  nitric  acid.  (Liebig.  Chemistry,  in  its  Application  to  Agrietd- 
lure  and  Physiology.  London,  1843,  p.  45.)  Rain-water,  deposited 
during  thunder-storms,  likewise  contains  nitrate  of  ammonia.  (Liebig.) 

IT.  The  quantity  of  ammonia  contained  in  the  air  has  been  determined 
by  Grbger.  (Ann.  Pharm.  56,  208,  by  Kemp,  and  quite  recently  by 
Fresenius,  {N.  Ann.  Ghim.  Phys.  26,  208.)  The  following  table  exhibits 
the  results  obtained.     1,000,000  parts  of  air  contain  : 


Ammonia. 

Oxide  of 
Ammonium. 

Carbonate  of 
Ammonia. 

GrSgcr 
Kemp 

Presenilis  (mean) 

0-333 
3-880 
0098 
0169 
0-133 

0-508 
5-610 
0-153 
0-257 
0-205 

0-938 
10-370 
0-283 
0-474 
0-379 

The  results  found  by  Groger — and  still  more  those  obtained  by  Kemp 
—are  certainly  too  high.  Grbger  appears  to  have  neglected  to  assure 
himself  that  the  re-agents  which  he  used  were  perfectly  free  from 
ammonia ;  and  Kemp's  mode  of  experimenting  (which  consisted  in  passing 
the  air  through  a  solution  of  corrosive  sublimate,  then  boiling  the  solu- 
tion, and  determining  the  ammonia  by  the  quantity  of  white  precipitate 
so  obtained),  is  not  to  be  depended  on.  From  the  experiments  of  Fre- 
senius, it  appears  that  the  quantity  of  ammonia  contained  in  the  air  during 
the  day,  is  to  that  which  is  present  during  the  night,  as  1  :  1'7.  The  com- 
parative smallness  of  the  quantity  present  during  the  day,  may  be  due  to 
two  causes  :  1 .  That  in  the  day-time,  more  ammonia  is  expended  in  the  nu- 
trition of  plants  j  2.  That  the  ammonia  which  accumulates  during  the  day 
and  night  together  is  dissolved  and  precipitated  by  the  dew  at  sunrise.  IT. 

When  some  weeks  have  passed  without  a  storm,  the  rain-water 
contains  lime  dissolved  in  excess  of  carbonic  acid.  (Stark,  Ann.  Phil. 
3,  1 40.) — In  hail  stones  which  fell  during  the  month  of  February,  sul- 
phate of  lime  was  found.  (Girardin,  J.  Pharm.  25,  390.) — On  evaporat- 
ing snow-water,  sulphate  of  lime  and  chloride  of  calcium  remain;  water 
from  thunder-showers  leaves  sulphate  of  lime.  In  fetid  vapours  and  moun- 
tain mists,  phosphoric  acid  is  found.  (Wiegmand,  Br.  Arch.  7,  199;  16, 
151.) — Rain-water  leaves,  on  evaporation,  carbonate  and  sulphate  of  lime, 
chloride  of  calcium,  silica,  and  a  trace  of  iron.  (Bohlig,  Kastn.  Arch.  2(f, 
419.) — All  the  rain-water  that  falls  at  Salzufieln  leaves,  on  evaporation, 
a  residue  which  for  10,000,000  parts  of  water  amounts,  during  May,  to 


ATMOSPHERIC  AIR.  .413 

onl^  8  parts,  which  is  the  minimam^  but  during  January,  to  65  parts, 
which  is  the  maximum. 

This  residue  contains  an  ammoniacal  salt,  chloride  of  sodium  with  a 
small  quantity  of  chloride  of  potassium,  carbonate  and  sulphate  of  lime, 
carbonate,  sulphate,  and  hydrochlorate  of  magnesia,  the  sesquioxides  of 
manganese  and  iron,  a  resinous  substance,  a  substance  soluble  in  water 
and  dilute  alcohol,  and  an  animal  substance,  soluble  only  in  potash. 
(Brandos,  Schw,  48,  153). — Zimmermann  states  {Kcutn.  Arch,  1,  257,) 
that  he  found  in  rain-water,  carbonic  acid,  hydrochloric  acid,  potash,  lime, 
magnesia,  manganese,  and  iron,  and  sometimes  also  nickel,  accompanied 
by  yyrrhin;  (yid,  seq). — Bertels  {J.  pr.  Chem,  26,  89)  says  that  he 
obtamed  from  3  pounds  of  snow-water,  as  much  as  86  grains  of  anhy- 
drous residue.  Unless,  howeyer,  the  eyaporation  is  conducted  in  metallic 
retorts,  with  eyery  precaution  to  prey  en  t  the  entrance  of  ashes  and 
particles  of  dust,  such  experiments  are  not  entitled  to  any  great  degree  of 
confidence. 

Organic  Matter  in  the  Atmosphere, — If  a  bottle  filled  with  distilled 
water  be  emptied  in  the  open  air  either  oyer  the  land  or  over  the  sea,  and 
a  small  quantity  of  nitrate  of  silyer  solution  put  into  the  bottle,  the  silyer 
salt  when  exposed  to  light,  becomes  first  red,  then  violet,  and  lastly 
deposits  a  dark-coloured  precipitate.  In  a  similar  manner  also,  rain 
and  snow-water  redden  a  solution  of  silver  exposed  to  light.  This  red 
colour  is  not  produced  by  chlorine  or  hydrosulphuric  acid,  but  by 
organic  matter. — Zimmermann  regards  this  organic  matter  as  a  peculiar 
substance,  and  names  it  Pyrrhin.  But  as  many  organic  substances  have 
the  property  of  reddening  a  solution  of  silver  exposed  to  light,  the  sup- 
position of  A.  Vogel  is  more  probable,  that  the  effect  is  due  sometimes 
to  one,  and  sometimes  to  another  kind  of  organic  matter,  difiused 
through  the  air  in  the  form  of  fine  particles  or  dust.  (See  Hermb- 
stadt,  Schw,  32,  281; — Kriiger,  Schw,  33,  379; — Lampadius,  Schw.  33, 
199;  J.  pr.  Clum.  10,  78;  13,  244;— Pfafl*,  Sdiw.  35,  396;  52,  311;— A. 
Vogel.  Gilb.  72,  282  &  336;  Kastn.  Arch,  15,  97; — Wiegmann,  Kastn. 
Arch.  16,  196; — Braconnot,  Ann.  Chim.  Phys.  44,  300: — Roubaudi,  J. 
Pharm,  21,  141;— Girardin,  J.  Pharm.  25,  390.) 

The  red  colour  produced  by  rain  or  snow-water  with  a  solution  of 
silver  under  the  influence  of  light,  is  destroyed  by  chlorine.  After  long 
standing,  the  red  mixture  Tnot  treated  with  chlorine)  deposits  a  precipi- 
tate which  becemes  black  oy  exposure  to  light,  and  yields  carbonate  of 
ammonia  by  dry  distillation.  In  a  garden  fragrant  with  flowers,  or  in  a 
hot-house,  or  under  a  receiver  containing  odoriferous  flowers,  a  dilute 
solution  of  silver  becomes  red,  if  exposed  at  the  same  time  to  the  sun's 
rays.  A  solution  of  volatile  oil  in  water,  alcohol  containing  fusel  oil, 
distilled  vinegar,  benzoic  acid,  a  solution  of  roasted  starch,  and  an  aqueous 
infusion  of  beech- wood,  or  peat,  produces  the  same  red  colour  in  a  solu- 
tion of  silver  exposed  to  light.  (A.  Vogel.) 

Water  from  hail-stones  which  fell  in  February,  1839,  presented  a 
milky  appearance  due  to  the  presence  of  a  small  quantity  of  organic  mat- 
ter, and  deposited  a  few  white  flakes;  when  mixed  with  solution  of  silver, 
it  remained  colourless  in  the  dark,  but  on  exposure  to  light  became  first 
reddish  and  then  brown,  and  deposited  a  scanty  grey  flocculent  precipitate, 
which,  on  bein^  heated,  evolved  fumes  having  an  einpyreumatic  animal 
odour.  When  the  water  was  evaporated  to  dryness  by  itself,  and  the  residue 
heated,  a  similar  empyreumatic  odour  was  emitted.  The  water  did  not 
contain  ammonia  ready  formed,  but  gypsum  (p.412).   (Girardin.) 


414  NTTSOGSN. 

Snow-water  eollected  at  Freiberg  daring  a  westerly  wlnH,  Imme- 
diatelj  becomes  turbid  on  the  addition  of  solution  of  silyer,  alter  whi<^ 
it  blackens  on  exposure  to  lights  because  it  contains  chloride  of  caJcinm; 
snow-water  collected  at  the  same  place  during  an  east  wind,  fives  scarcely 
any  turbidity,  but  becomes  red  when  exposed  to  the  snns  rays, — and 
then  deposits  a  dark-coloured  precipitate,  from  which  a  boiling  solution  of 
common  salt  remores  only  the  chloride  of  silver  present.  The  residue 
bums  before  the  blow-pipe  with  a  faint  light  and  leaves  metallic  silver. 
The  stronger  the  wind  which  blows  from  the  continent  the  richer  is  the 
air  in  matter  which  reddens  the  silver  solution.  The  matter  thus  con- 
veyed by  the  wind  probably  consists  of  dust  from  the  sur&oe  of  the 
ground.  (Lampadius.) 

Two  thousand  measures  of  air  freed  from  every  trace  of  carbonic  acid, 
and  exploded  with  hydrogen  gas,  yield  0*94  measures  of  carbonic  acid 
gas ;  so  that  the  air  probably  contains  carbonic  oxide  gas  [or  marsh  gas;, 
or  some  other  organic  substance].  (Saussure,  P(ygg,  19,431.) 

If  the  air  of  Paris  is  first  passed  through  a  bottle  containing  oil  of 
vitriol — ^then  through  a  long  chloride  of  calcmm  tube — then  throu£^h  two 
tubes  full  of  asbestos  moistened  with  oil  of  vitriol  (by  the  equality  in 
weight  of  the  latter  before  and  after  the  experiment  it  is  ascertained 
that  the  air  is  previously  rendered  perfectly  dry) — ^then  into  a  tube  con- 
taining ignitea  copper  turnings,  in  which  the  combination  of  the  hy- 
drogen in  the  air  with  the  oxygen  is  effected — and  lastly,  into  a  weighed 
tube  containing  asbestos  moistened  with  oil  of  vitriol :  the  increase  in 
weight  of  the  latter  gives  the  quantity  of  water  produced,  and  conse- 
quently the  quantity  of  hydrogen  present  in  the  air,  independent 
of  that  which  is  in  the  form  of  aqueous  vapour.  In  this  manner  it  is  found 
that  100  parts  by  weight  of  air  examined  on  different  days,  contain  from 
00002  to  00008  parts  by  weight  of  hydrogen.  The  latter  is  probably 
exists  partly  as  hydrogen  gas,  partly  as  hyorosulphnric  acid  gas  (which 
however  would  be  decomposed  in  passing  throngn  the  oil  of  vitriol),  and 
partly  a£  marzk  g<u.  The  latter  is  evolved  from  every  description  of 
stagnant  water,  from  coal  mines,  and  in  the  processes  of  combustion;  but 
can  accumulate  in  the  atmosphere  in  small  quantities  only,  because,  like 
free  hydrogen,  it  is  consumed  by  electric  dischar^  in  the  air.  Atmo- 
spheric air  from  a  pestilential  region  in  South  America,  when  passed 
through  a  chloride  of  calcium  tul^  into  an  empty  red-hot  tube,  yielded 
water,  the  quantity  of  which  corresponded  to  O'OOl?  of  hydrogen  in 
100  parts  by  weight  of  air.  When  the  air  has  been  rendered  whole- 
some by  thoroughly  draining  the  morasses,  it  contains  only  0*0004 
of  hydrogen.  If  the  air  is  deprived  of  its  aqueous  vapour  by  means  of 
oil  of  vitriol  instead  of  chloride  of  calcium,  it  does  not  yield  any  water 
on  being  transmitted  through  the  red-hot  tube,  because  the  oil  of  vitriol 
retains  the  organic  matter  in  which  the  hydrogen  is  present.  Oil  of 
vitriol  exposed  in  a  watch-glass,  rapidly  blackens  in  pestilential  locali- 
ties—for example,  in  the  neighbourhood  of  a  marsh  in  the  Depart- 
ment de  TAin, — also  in  Maracey,  Valencia,  and  Cartage  in  South 
America,  during  the  unhealthy  season.  If  a  watch-glass  full  of  warm 
water,  and  an  empty  watch-glajBS  are  exposed  at  uie  same  time  in 
an  unhealthy  atmosphere,  till  the  latter  is  covered  with  dew,  then  one 
drop  of  oil  of  vitriol  put  into  each,  and  the  contents  of  each  evaporated  to 
dryness — no  residue  remains  in  the  first,  but  a  carbonaceous  residue  in 
the  second^ — ^because  the  dew  charged  with  miasma  could  not  condense  on 
the  former.    If  the  accidental  presence  of  insects  or  of  dust  were  the 


ATMOSPHERIC  AIR.  415 

cause  of  the  blackening  of  the  oil  of  vitriol^  both  watch-glasses  wonld 
behave  in  the  same  manner  with  that  reagent.  (Boossingaalt,  Ann.  CMm, 
Phys.  57,  148;  also  J.  pr.  Chem.  S,  151.) 

Moscati  {GUb.  48,  12)  suspended  glaas  globes  filled  with  ice  close 
over  the  unhealthy  rice-fields  of  Tuscany.  The  hoar-frost  deposited  on 
them  during  the  night  yielded,  on  thawing,  a  transparent  water  wliich  in 
a  short  time  deposited  small  fiakes  of  a  substance  containinff  uitroffen, 
and  after  a  while  became  putrid.  Similar  results  were  obtained  in 
'  an  hospital.     Water  collected  oy  Rigaud  de  I'lsle  on  the  marshes  of  Lan- 

,  guedoc  behaved  in  a  similar  manner;  with  a  solution  of  silver  it  gave  a 

precipitate  which  soon  became  purple.     Whether  the  organic  matter  con- 
I  densed  with  the  water  was  really  the  miasma,  remains  undecided.     At 

i  all  events  A.  Vogel  (/.  pr,  Cnem.  4,279)  by  exposing  in  his  lecture- 

room,  immediately  after  the  departure  of  the  audience,  glass  cylinders 
\  filled  with  a  freezing  mixture   and  standing  on  plates,  obtained  a  trans- 

Sarent    water   which   behaved    similarly   to   the   above.      After  some 
ays,   it  deposited  first  white  and  then  ffreen  flakes,  and  acquired  a 
I  mouldy  smell.    Mixed  in  a  fresh  state  with  a  solution  of  silver,  it  re- 

[  mained  colourless  and  transparent  in  the  dark;  but  on  exposure  to  the 

6un*s  rays,  assumed  a  dark  port-wine  colour  in  the  course  of  a  few  minutes, 
then  became  colourless,  and  deposited  a  black  powder.  Hence  non- 
contagious organic  particles  diffused  through  the  atmosphere,  may  also 
produce  water  exhibiting  the  above  characters. 

The  following  circumstances  appear  to  promote  the  disengagement  of 
I  miasmata.  The  putrefaction  of  organic  substances  exposed  in  hot  weather 

to  the  action  ot  air  and  moisture.  Stagnant  waters  exhale  miasmata,  in 
greatest  quantity  when  they  are  completely  drained  and  the  air  is  allowed 
to  act  on  the  decomposing  organic  matter.  (Ferguson.)  The  rotting  of  flax 
and  hemp  under  water  produces  miasma.  The  clearing  of  forests  m  South 
America  renders  the  surrounding  country  unhealthy,  in  consequence  of  the 
decaying  of  the  trees  ;  after  a  period  of  six  years  or  more,  the  locality  may 
become  healthy  again.  (Boussingault.)  The  admixture  of  fresh  water 
containing  organic  matter  with  sea-water  in  which  sulphates  are  present, 
gives  rise  in  hot  climates  to  the  evolution  of  miasmata ;  as  proved  by 
Geor^ni  in  Italy,  and  by  Daniell  (p.  191)  on  the  west  coast  of 
Africa.  The  conversion  of  the  alkaline  sulphates  into  alkaline  hydrosul- 
phates  by  the  organic  matter  appears  to  have  some  relation  to  the  forma- 
tion of  the  miasma.  Hence,  also,  miasmata  are  produced  after  an  over- 
flowing of  the  land  by  sea-water ;  and,  according  to  Savi,  when  a  mineral 
spring  containing  salts  of  sulphuric  acid  overflows  its  borders.  Elevated 
spots  in  the  neighbourhood  of  unheal th^r  localities  are  frequently  quite 
free  from  disease.  A  veil  before  the  face  is  said  to  be  a  protection  from 
miasmata.  Hence  the  contagious  matter  would  appear  to  oe  heavier  than 
air,  and  to  exist  in  it  not  in  the  form  of  vapour,  but  in  fine  flakes  or  par- 
ticles. (Boussingault.) — Heusinger  {J,  pr.  Chem.  8,  484)  supposes,  with 
great  probability,  that  vegetable  or  animal  organizations  are  contained  in 
miasmata.  [On  Miasma  or  Malaria,  see  also  Mac  Culloch,  N.  Qtiart.  J.  of 
Se.  2,  39;  Hopkins,  Phil.  Mag.  J.  14,  104;  Savi,  Ann.  Chim.  Fhy$. 
78,  344.] 


1 


416  NITROGEN. 

Nitrogen  akd  Htdroqen. 

A.     Amidooen.    NH*=Ad. 

Not  known  in  the  separate  state,  but  only  in  combination  with  cer- 
tain metals  and  organic  compounds. 

The  Metallic  Amides  {Amidmetalle,  Amidides  MetaUiqited)  are  formed  : 
1.  By  heating  potassinm  or  sodium  in  ammoniacal  gas,  which  they  absorb 
with  separation  of  \  of  the  hydrogen. 

K  +  NH»«  K,NH«  +H. 
— 2.  On  mixing  certain  metallic  chlorides  and  metallic  salts  with  aqueous 
solution  of  ammonia.     Thus  : 

2HgCl  +  2NH»  =  Hg\d,  HgCl  +  NH^Cl. 
(See  more  particularly  Mercury.) — The  amidogeu  in  these  compounds 
takes  the  place  of  oxygen,  chlorine,  or  a  similar  salt  radical ;  many  of  the 
compounds  also  are  known  only  in  combination  with  metallic  chlorides  or 
metallic  oxides.  (See  Theories  on  Ammonia,  pp.  428 — 430.) 

B.    Ammonia.    NH*. 

AmToonium,  Volatife  alkali,  fiucfuiges  alkali,  jlu<^iges  Laugensalz,  Ammo- 
niaque,  Ammoniacum; — In  the  gaseous  form :  Ammoniacal  gas.  Alka- 
line air,  alkalische  Luft,  urinose  Luft,  Gas  ammoniaque.  Gas  ammo- 
nium. Regarded  by  Kane  as  Amide  of  hydrogen,  Hydramide,  Ami- 
dide  d'hydrogine.     nAd. 

Sources, — In  the  air,  as  carbonate  of  ammonia  (p.  412). — ^In  sea- 
water.  (Marcet,  Pfaff.)  In  yarious  mineral  waters  combined  with 
hydrochloric  or  other  acids,  as  in  the  saline  springs  at  Chelten- 
ham and  Gloucester  (Murray,  Phil.  Mag.  Ann,  6,  284) ;  in  the 
ferruginous  waters  of  Passy  and  Chaudes  Aigues  (Chevallier);  in  the 
waters  of  Bourboune-les- Bains,  Fais-Billot,  St.  Mart,  Ste.  Marguerite, 
Jaude,  and  St.  AUyre.  (Bastien,  Chevallier  &  Aubergier,  J.  Chim.  Med, 
10,  33.) — In  river-water,  e,  g.  in  the  water  of  the  Seine.  (Collard  de  Mar- 
tignv.) — In  peat-earth.  (Collard.) — As  sal-ammoniac,  in  the  rock-salt  of 
Hall  in  the  Tyr<»l,  and  in  the  common  salt  of  Rosenheim,  Friedrichshall, 
Oeb,  Kissingen,  and  Diirkheim.  (A.  Vogel,  J.pr.  Chem.  2,  290.)  In  the 
sal-ammoniac  of  volcanos. — The  rust  of  iron  contains  ammonia.  (Vauque- 
lin,  Ann.  Chim.  Fhys.  24,  09.)  Specular  iron,  bloodstone,  magnetic 
iron  ore,  ilvaite,  and  also  sesqui-oxide  of  iron  formed  during  a  recent 
conflagration,  not  only  disengage  ammonia  when  heated,  but  give  it 
up  even  to  hot  water,  which  on  subsequent  evaporation  with  hydro- 
chloric acid,  leaves  sal-ammoniac.  (Chevallier,  Ann.  Chim,  Phys.  34, 
109;  also  J.  Chim.  Med,  3,  173;  also  Kastn.  Arch.  10,  388.)  Hydrated 
eesqui-oxide  of  iron  also  from  Marmato,  extracted  from  the  middle  of  a 
V  ein  of  great  thickness  by  a  deep  boring,  contains  ammonia.  (Bous- 
singault,  Ann.  Chim.  Phys.  43,  334.)  Most  kinds  of  clay  evolve 
ammonia  when  digested  with  solution  of  potash.  (Bonis,  Ann.  Chim, 
Phys.  35,  333;  also  J.  Pharm.  13,  282.) — The  ammonia  in  sesqui-oxide 
of  iron  and  in  clay  has  probably  been  chiefly  absorbed  from  the  atmo- 
sphere, but  partly  also  formed  by  the  oxidation  of  the  iron  in  contact 
with  air  and  water.  {Vid,  seq.)      Ammoniacal  salts  are  also  contained 


AMMONIA-  417 

in  the  juice  of  many  plants  (Pleischl,  ZeiUchr,  Phy9.  Math.  2,  156),  and 
in  most  animal  fluids,  especially  in  the  urine. 

Formation. — 1.  From  morganic  aubstances. — a.  On  burning  a  mixture 
of  oxygen,  nitrogen,  and  excess  of  hydrogen,  nitrate  of  ammonia  is 
produced.  (Theod.  Saussure.) — Water  containing  atmospheric  air  yields 
nitric  acid  at  the  positive  pole  of  a  voltaic  battery  and  ammonia  at  the 
negative  pole.  (Sir  H.  Davy.) — A  mixture  of  1  volume  of  nitrogen  gas 
with  3  volumes  of  hydrogen  transmitted  through  a  red-hot  tube,  does 
not  yield  ammonia.  It  likewise  remains  unchanged  when  confined  by 
mercury  having  a  stratum  of  dilute  nitric  acid  on  its  surface,  and  snnk  540 
metres  or  295  fathoms  deep  in  the  sea,  where  it  must  sustain  a  pressure 
of  50  atmospheres.  (Laroche,  Sdiw.  1,  123  &  172.) — Neither  does  spongy 
platinum  induce  combination.  (Kuhlmann.) 

&.  Hydrogen  at  the  moment  of  being  set  free  from  another  compound, 
i,  e,  in  the  nascent  state  (I.  37,  38),  in  contact  with  nitrogen  gas,  fre- 
quently produces  ammonia.     Moistened  iron  filings  in  contact  with  nitro- 
gen gas  or  atmospheric  air  at  ordinary  temperatures,  indnce  the  formation 
of  ammonia.  (Austin,  Ann.  Chim.  2,  260;  Chevallier,  Ann,  Chim.  Phys. 
34, 109;  Berzelius,  Ja/tre«6cricA^,  8,  115.)   Hall  {Ann.  Chim.  Phys.  11,  42) 
did  not  succeed  with  the  above  experiment.    In  the  preparation  of  jEthiops 
mariialis  also,  in  which  the  iron  filings  are  covered  with  a  deep  stratum 
of  water,  ammonia  is  produced,  because  the  water  contains  nitrogen 
gas  in  solution.   TKuhlmann.) — Moistened   zinc   filings  contained  in   a 
bottle  in  which  air  is  present,  give  rise  to  the  formation  of  ammonia. 
(CoUard  de  Martigny,  J.  Chim.  Med.  3,  516.) — A  wet  mixture  of  iron 
filings  and  sulphur  likewise  produces  ammonia  when  exposed  to  the 
air.  (Austin.) — When  liver  of  sulphur  is  fused  with  an  equal  weight 
of  iron  filings,  and  water  dropt  on  the  mass  while  still  warm,  ammonia 
is  evolved.  (Hollnnder,  Kastn.  Arch.  12,  402.) — The  hydrates  of  potassa, 
soda,  baryta,   or  lime,   disengage  large  quantities  ot    ammonia,    when 
heated  with  potassium,   arsenic,  zinc,  tin,   lead,  or  iron;  with  copper, 
very  small  quantities ;  and  with  gold  and  other  noble  metals,  none.     The 
ammonia  is  produced  not  only  on  heating  the  mixture  in  the  air,  but  also 
on  heating  it  in  hydrogen  gas.  (Faraday.)     The  formation  of  the  ammo- 
nia in  an  atmosphere  of  hydrogen  is  explained  by  Bischof  {Schw.  45,  204) 
as  arising  from  the  difficulty  of  obtaining  hydrogen  gas  perfectly  free 
from  atmospheric  air  and  consequently  of  nitrogen  gas.     Moreover,  aa 
remarked  by  Reiset,  when  the  oil  of  vitriol  b3r  which  the  hydrogen 
gas  is  to  be  evolved,  contains  nitric  oxide  or  nitric  acid,  nitnc  oxide 
will    be   mixed   with    the   hydrogen  —  a  circumstance  not  previously 
taken  into  account.     When  iron  filings  are  heated  with  a  concentrated 
solution  of  potash  merely  to  a  temperature  of  130"^,  either  in  the  air  or 
in  hydrogen  gas  containing  nitric  oxide,  hydrogen  and  ammonia  are 
evolved;  in  pure  hydrogen  gas,  however,  this  effect  does  not  take  place. 
(Heiset,  Compt.  Rend.  15,  162.) — ^When  turmeric  paper  is  laid  on  plates 
of  zinc,  lead,  or  iron,  moistened  with  water,  the  paper  becomes  reddened 
in  several  places  in  the  course  of  a  quarter  of  an  hour ;  on  heating  it,  the 
colour  disapjpears.     If  the  wet  plates  are  covered  with  white  paper,  and 
the  latter  after  some  time  is  introduced  into  a  glass  tube,  ammonia  is  dis- 
engaged on  the  application  of  heat.  (Becquerel,  Ann.  Chim.  Phys.  52,  248.) 
— Smithy  scales  reduced  to  powder  and  ignited  in  a  covered  crucible, 
produce  ammonia  when  moistened  with  water  and  kept  in  a  vessel  con- 
taining air.  (Sprengel,  J.  pr.  Chem.  1, 162.)— Hydmted  protoxide  of  iron 

VOL.   II.  2   E 


418  NITROGEN, 

precipitated  from  green  vitriol,  produces  small  quantities  of  ammonia  in 
the  air,  till  it  is  converted  into  hjdrated  sesqui-oxide.  (Sanean,  J,  Fharm. 
23,  218;  also  J,  pr.  Chem,  13,  178.) — When  grey  sulphide  of  anti- 
mony is  boiled  with  carbonate  of  soda,  in  the  preparation  of  mineral 
kermes,  the  liquid  from  which  the  kermes  is  deposited  on  cooling,  evolves 
ammonia,  especially  if  it  has  been  repeatedly  boiled  with  the  undis- 
solved sulphide  of  antimony.  (Leroy,  J.  Fharm.  10,  554;  also  Ann, 
Fharm.  13,  140;  also  J.  pr,  Chem.  3,  108.)  In  this  case,  the  hydrosul- 
phuric  acid  is  probably  the  source  of  the  hydrogen.  (See  Herzog's  experi- 
ment, p.  200.) 

c.  Nitrogen  in  the  ncucent  state  is  capable  of  combining  with  hvdro- 
gen  gas. — A  mixture  of  2  volumes  of  nitric  oxide  gas  with  5  volumes 
of  hydrogen  passed  over  spongy  platinum  (p.  378)  yields  ammonia. 
(Hare.)  —  Nitric  oxide  gas  passed  together  with  hydrogen  through  a 
red-hot  tube,  yields  ammonia  only  when  the  tube  contains  porous  sub- 
stances. Finely  divided  pumice-stone  produces  a  very  large  quantity; 
still  more  is  produced  by  sesqui-oxide  of  iron,  which,  when  gently 
heated  in  the  glass  tube,  quickly  becomes  ignited  in  the  stream  of  gas; 
the  oxides  of  zinc,  tin,  and  copper  act  less  energetically.  The  alternate 
reduction  and  oxidation  of  the  metal  doubtless  contributes  to  the 
formation  of  the  ammonia.  (Reiset,  Ccmpt,  Eend,  15,  162.) — A  mix- 
ture of  nitrous  oxide  and  excess  of  hydrogen  passed  over  spongy  pla- 
tinum or  platinum  black  contained  in  a  tul^,  undergoes  no  alteration  at 
ordinary  temperatures ;  but  on  heating  the  platinum,  it  yields  a  consider- 
able quantity  of  ammonia. — In  a  mixture  of  nitric  oxide  or  hyponitrio 
acid  vapour  and  hydrogen,  cold  spongy  platinum  becomes  bright  red- 
hot  and  frequently  gives  rise  to  dangerous  explosions;  the  whole  of 
the  nitrogen  is  converted  into  ammonia.  Platinum-black  does  not  act 
till  heated  to  redness,  and  does  not  become  incandescent.  Spongy  plati- 
num when  cold  does  not  affect  hydrogen  gas  saturated  with  nitric  acid 
vapour;  but  when  heated,  it  becomes  red-hot  and  converts  all  the  nitrogen 
into  ammonia.  Platinum-black  also  does  not  act  unless  it  is  first  heated, 
and  even  then  does  not  become  incandescent  in  the  gaseous  mixture. 
(Kuhlmann,  Ann.  Fharm.  29,  284.) 

d.  Both  nitrogen  and  hydrogen  in  the  ncuaent  ttate. — Moist  nitric 
oxide  gas  transmitted  over  red  hot  iron  filings  yields  ammonia.  (Milner, 
Crell,  Ann,  1795,  1,  554.) — Nitric  oxide  gas  in  contact  with  moistened 
iron  or  tin  filings,  aaueous  hydrosulphnric  acid,  or  the  aqueous  solution  of 
an  alkaline  hydrosulphate  or  hydrosulphite,  is  decomposed,  with  formation 
of  ammonia.  (Kirwan,  Priestley,  Austin,  H.  Davy.) — Hyponitric  acid 
decomposes  aqueous  hydrosulphnric  acid,  with  formation  of  a  small  quan- 
tity of  ammonia.  (Johnston,  Millon.) — In  the  decomposition  of  nitric  acid 
by  tin,  nitrate  of  ammonia  is  one  of  the  products.  (Priestley,  ScftmM  85.) 
The  same  thing  occurs  with  zinc,  cadmium,  and  iron,  but  not  with  potas- 
sium or  sodium.  (Kuhlmann,  Ann,  Pkarm,  27,  37.)  A  mixture  of  iron 
filings  and  very  dilute  nitric  acid  left  over  night  in  a  suitable  vessel,  was 
found  to  be  covered  with  an  efflorescence  of  carbonate  of  ammonia. 
(Fabbroni,  Scher,  J,  8,  323;  also  Gi^,  5,  359.)— Iron  filings  covered  to 
a  finger's  depth  with  a  mixture  of  1  part  of  fuming  nitric  acid  and 
6  parts  of  water,  evolves  in  the  course  of  a  few  days  a  large  quantity 
of  ammonia;  with  12  parts  of  water,  a  smaller  quantity;  and  with 
16  parts,  none  at  all.  (Bischof,  Sckw,  56, 125.) — Zinc  filings  covered  with 
a  solution  of  nitrate  of  copper,  produce  ammonia.  Iron  filings  mixed 
with  nitric  acid  or  with  nitrate  of  copper  in  a  close  vessel  exhale  am- 


AMMONIA^  419 

monia  after  some  timeJ  (Austin.) — ^Wben  nitrate  of  silver  iJa  solation  is 
precipitated  at  the  boiling  point  hj  means  of  iron,  the  liquid  is  fonnd  to 
contain  ammonia.  (Wetzlar,  Schw,  60, 130.) — Dilute  sulphuric  acid  mixed 
in  proper  proportions  with  nitric  acid,  dissolves  zinc,  iron,  or  tin  without 
any  evolution  of  gas,  but  sulphate  of  ammonia  is  formed  at  the  same 
time.  (Mitscherlich;  see  also  1.,  420.) — ^Nitre  when  i^ited  with  hydrate 
of  potash,  does  not  evolve  ammonia;  but  on  the  addition  of  sine  a  large 
quantity  is  evolved.  (Faraday.) — ^A  mixture  of  1  part  of  nitre  and  3  parts 
of  hydrate  of  potash  heated  with  20  times  its  weight  of  iron  filings, 
gives  off  a  large  quantity  of  ammonia,  besides  hydrogen  and  nitrogen 
^ases.  rOobereiner,  Sehw.  47,  120.) — ^Zino,  immersed  together  with  iron 
in  a  solution  of  potash  containing  nitre,  yields  ammonia;  whereas,  if 
the  nitre  is  absent,  nothing  but  hydrogen  is  disengaf;ed  by  the  iron. 
(Ddbereiner,  J.  pr,  Chem.  15,  318.^ — Ammonia  is  likewise  formed  in  the 
aecompositions  of  phosphide,  sulphide,  iodide,  and  chloride  of  nitrogen  by 
water. 

2.  From  Organic  Matter,— a.  When  hydrate  of  potash,  soda»  baryta, 
or  lime,  is  heated  with  suffar,  linen,  oxalates,  tartrates,  or  many  other 
organic  compounds  free  from  nitrogen,  in  a  vessel  containing  atmo- 
spheric air  or  hydrogen  gas,  ammonia  is  disengaged.  (Faraday.)  (With 
respect  to  the  hydrogen,  vid.  Reiset's  observation,  p.  417). — 1  gramme 
of  sugar  mixed  with  an  excess  of  soda-lime  (that  is,  a  mixture  of  2 
parts  of  lime  and  1  part  of  hydrate  of  soda^  prepared  by  mixing  slaked 
lime  with  a  solution  of  caustic  soda,  evaporating  to  dryness  and  igniting,) 
and  heated  to  redness  in  a  tube  containing  air,  evolves  a  quantity  of 
ammonia  containing  0*0127  grm.  of  nitrogen.  If  hydrogen  gas  is  passed 
through  the  tube  for  six  hours  previously,  a  quantity  of  ammonia  is 
obtained  equivalent  to  0*0048  grm.  of  nitrogen.  It  appears,  therefore, 
that  a  portion  of  the  atmospheric  nitrogen  adneres  to  the  porous  mixture 
so  tenaciously  that  it  cannot  be  removed  by  the  current  of  hydrogen. 
The  foimation  of  ammonia  appears  to  depend  upon  this  circumstanco— 
that  the  charcoal  produced  when  the  mixture  is  heated,  absorbs  nitro^n 
from  the  adhering  atmospheric  air  and  produces  a  metallic  cyanide,  which 
on  continuing  the  heat,  undergoes  mutual  decomposition  with  the  remain- 
ing alkaline  hydrate,  and  ammonia  is  one  of  the  products  of  the  decom- 
position. If  nitrogen  gas  be  passed  over  a  mixture  of  soda-lime  and 
sugar  during  ignition,  the  quantity  of  ammonia  obtained  is  not  much 
larger ;  the  charcoal  appearing  only  at  the  moment  of  its  elimination  to 
be  capable  of  absorbing  the  nitrogen  already  condensed  in  the  pores  of  the 
mixture.  (Reiset,  Compt,  Bend,  15,  134.) 

h.  Paste  prepared  from  starch  free  from  nitrocfen,  evolves  ammonia 
during  its  decomposition  in  the  open  air.  (Collard  de  Martigny.) 

c,  A  mixture  of  defiant  gas,  vapour  of  alcohol  or  nitrous  ether,  and 
nitric  oxide  gas,  transmitted  over  heated  spongy  platinum,  yields  hydro- 
c^nate  of  ammonia,  besides  other  products.  (Kuhunann.])  When  a  solu- 
tion of  platinum  in  aqua  regia,  still  containing  free  nitric  acid,  is  super- 
saturated with  potash,  mixed  with  alcohol,  and  exposed  to  the  sun's  rays, 
it  deposits  platinum  black,  and  at  the  same  time  becomes  continually  richer 
in  free  ammonia:  no  nitrogen  is  absorbed  from  the  air  in  this  case;  con- 
sequently the  nitric  acid  combined  with  the  potash  must  be  the  source  of 
the  nitrogen.  (Dobereiner,  Schw,  63,  476.)  Nitre  heated  with  gum 
(Vauquelin),  or  with  f  of  its  weight  of  cream  of  tartar,  produces  am- 
monia. ^Pagenstecher,  iT.  TV.  3,  1,  470.) 

,  d.  Most  organic  compounds  containing  nitrogen  yield  ammonia  when 

2  E  2 


420  NITROGEN. 

decompotett  in  yarions  ways :  namely  by  dry  ot  destrnctire  distillationi 
by  heating  with  hydrate  of  potash,  by  putrefaction,  by  the  vinons  fer- 
mentation,  &c.  Ammonia  is  yery  frequently  produced  from  cyanogen 
and  its  compounds.  In  this  place  may  also  be  cited  the  observations  of 
Woodhouse,  Sir  H.  Davy  {GUb,  35,  471 ;  37,  163),  and  Hollunder  {Kastn. 
Arch.  12,  402),  whence  it  appears  that  an  ignited  mixture  of  potash  and 
wood  charcoal  (which  contains  a  small  quantity  of  nitrogen),  or  ignited 
crude  tartar  (since  crude  tartar  contains  a  ferment  rich  in  nitrogen)^  evolves 
ammonia  when  moistened  with  water.  For,  cyanide  of  potassium  is  pro- 
duced during  the  ignition  and  is  decomposed  on  the  addition  of  water 
by  the  heat  evolved  and  the  excess  of  potash  present.  Davy,  however, 
found  that  a  larger  quantity  of  ammonia  is  obtained  when  the  ignited 
mixture  of  charcoal  and  hydrate  of  potash  is  suffered  to  cool  in  contact 
with  the  air — ^a  fact  which  accords  with  the  observations  of  Faraday  and 
Reiset  (p.  419.) 

Preparation. — 1.  In  ths  gaseous  state :  1  part  of  sal-ammoniac  is 
mixed  with  2  parts  of  pounded  lime,  and  the  mixture  gradually  heated  in 
an  iron  or  glass  retort.  (Sck.  63) :  CaO  +  NH»,  HCl  =  CaCl  +  HO  + 
NH*.     The  gas  is  collected  over  mercury. 

2.  In  the  liquid  state : — a.  From  ammonio-chloride  of  silver  (I.,  286.) 
Chloride  of  silver  saturated  with  ammoniacal  gas  and  heated  in  one  arm 
of  the  tube,  fuses,  and  disengages  ammonia  with  effervescence ;  the  am- 
monia condenses  in  the  other  arm  which  is  kept  cool  with  ice.  As  the 
chloride  of  silver  cools,  the  ammonia  is  again  absorbed,  with  disengage- 
ment of  heat  which  raises  the  temperature  to  38°  (100*4°  F.),  while  the 
opposite  branch  of  the  tube  becomes  extremely  cold.  (Faraday.)  For 
expelling  the  ammonia  from  the  chloride  of  silver  a  heat  of  112° — 119^ 
(234^ ....  246°  F.)  is  necessary.  If  the  arm  containing  the  chloride  of  silver 
is  suffered  to  cool,  the  ammonia  in  the  other  arm  begins  to  boil  and  cools 
it  to  -h  6°  (A2'S°  F.);  but  if  the  chloride  of  silver  arm  is  rapidly  cooled 
to  +12'^  (53'6^  F.),  the  ammonia  boils  with  great  violence  and  that 
portion  of  the  tube  becomes  covered  with  ice.  (Niemann,  £t\  Arch,  36, 180.) 
— 6.  Ammoniacal  gas  is  first  passed  through  a  long  tube  containing 
hydrate  of  potash,  and  then  into  a  vertical  tube,  sealed  at  bottom,  and 
cooled  by  a  mixture  of  chloride  of  calcium  and  ice  to  a  temperature  of 
—  40*^.  (Bunsen,  Fogg.  46,  102.)  This  tube,  if  kept  as  cold  as  possible, 
may  afterwards  be  sealed  at  top  also;  Guyton  Morveau  {Scher.  J.  3,  57) 
likewise  condensed  the  gas  by  a  cold  of  —  52°. 

3.  In  the  solid  state:  By  Faraday's  method  {vid.  I.,  287.) 

Properties.  In  the  solid  state,  colourless,  translucent,  crystalline, 
heavier  than  the  liquid;  melts  at  —75°  (—113°  F.) — In  the  liquid  state, 
colourless,  and  very  mobile;  of  specific  p^ravity  0*76;  more  refractive  than 
water  or  liquid  hydrosulphuric  acid.  (Faraday.)  Boils  under  a  pressure 
of  0-7493  met.  at  —  33*7^  (282"  F.)  (Bunsen.)  It  conducts  the  current 
of  a  voltaic  battery  imperfectly  and  with  slight  evolution  of  gas,  probably 
arising  only  from  the  presence  of  a  trace  of  water.  (Kemp.)  The  gas 
is  colourless.  [For  the  tension,  specific  gravity,  and  refractive  power 
of  the  gas,  viae  I.,  261,  280  and  95.]  It  has  a  very  pungent,  exciting 
and  enlivening  odour;  animals  die  when  immersed  in  it;  it  is  not  cor- 
rosive; tastes  highly  alkaline;  reddens  turmeric,  even  perfectly  dry 
turmeric  paper,  and  turns  violet  juice  green;  these  changes  of  colour 
disappear  however  on  exposure  to  the  air.     The  gas  is  feebly  combustible; 


AMMONIA.  421 

burns  in  immediate  contact  with  the  flatne  of  a  candle,  with  a  pale  light; 
bat  the  combustion  does  not  go  on.  It  does  not  support  the  combustion 
of  other  bodies. 

Calculation. 


N  14 

••...• 

.  82-35  . 
.  17-65  . 

80-7  

81*13 

3H  3 

19-3  

18-87 

NH» 17 

5M 

.100-00  . 

Vol. 

....  1  

....  3  

lOO'O 

100-00 

Nitrogen  ( 
Hydrogen 

Sp.gr.            Vol. 
..  0-9706      =      4  .... 
..  0-2080      =      H.... 

....  0-4853 
....  01040 

Ammoniacal  gas  2  1-1786      =      1  0*5893 

(NH'  =  88-52  +  3  .  6*24  =  107-24.    BerieUufl.) 

DecomposUians. — 1.  a.  When  a  succession  of  electric  sparks  is  trans- 
mitted through  ammoniacal  gas  rendered  as  dry  as  possible,  it  doubles  its 
volume  and  is  resolved  into  a  mixture  of  3  volumes  of  hydrogen  gas  and 
1  volume  of  nitrogen.  100  volumes  of  ammoniacal  gas  were  found  by  W. 
Henry,  in  his  eariier  experiments,  to  yield  from  180  to  199  volumes;  in  his 
later  experiment,  from  200  to  204  volumes;  C.  Berthollet  obtained  194^  and 
Am.  Berthollet  204  volames,  of  decomposed  gas.  This  caseous  mixture, 
according  to  W.  Henry's  first  experiments,  contained  m  100  volumes, 
26*25  nitrogen  and  73*75  hydrogen  gas;  according  to  his  last,  25  nitrogen 
and  75  hydrogen;  and  according  to  Am.  Berthollet  24*5  nitrogen  to  75-5 
hydrogen  gas. — h.  A  red  heat  effects  the  same  decomposition, — for  instance, 
the  transmission  of  ammoniacal  gas  through  a  narrow  glass  tube  (Priestley) 
or  a  porcelain  tube  (Am.  Berthollet)  heated  to  redness.  Ammoniacal  gas 
is  scarcely  acted  on  in  an  ignited  porcelain  tube  when  clean  and  emptj, 
but  more  readily  when  it  contains  tragments  of  porcelain;  with  still  greater 
facility  when  it  contains  platinum,  silver,  or  go^d  wire ;  more  easily  still 
when  it  contains  copper  wire,  and  most  quickly  and  completely  when  iron 
wire  is  introduced.  These  metals,  for  the  most  part,  do  not  undergo  any 
observable  alteration  in  weight;  but  copper  and  iron  become  brittle,  while 
gold  and  platinum  remain  perfectly  unchanged.  The  higher  the  tem- 
perature, the  more  easily  is  the  decomposition  effected.  (Th^nard.  Vid. 
Metallic  Nitrides^  Nitrate  of  Irorty  and  Nitrate  of  Copper.) 

2.  a.  A  mixture  of  2  volumes  of  ammoniacal  gas  with  not  less  than 
1,  and  not  more  than  6  volumes  of  oxygen  gas,  may  be  exploded  by  the 
electric  spark.  In  this  case,  when  the  oxygen  is  in  excess,  the  products 
are  nitrogen  gas,  water,  and  nitrate  of  ammonia,  in  the  form  of  a  cloud; 
when  the  ammonia  predominates,  nitrogen  gas,  hydrogen  gas,  and  water 
are  produced,  because  the  unconsumed  ammoniacal  gas  is  resolved,  bj 
the  heat  disengaged,  into  its  gaseous  elements.  (W.  Henry.)  Ammoniacal 
gas  passed  in  a  small  stream  into  oxygen  gas,  may  be  set  on  fire  and  burns 
with  a  small  yellow  fiame.  (Berzeiius.)— Ammoniacal  gas  mixed  with 
atmospheric  air  enlarges  the  flame  of  a  burning  body,  without,  however, 
causing  the  combustion  to  proceed  further ;  in  whatever  proportions  the 
mixture  may  be  made,  it  cannot  be  exploded  by  the  electric  spark ; 
but  a  continuous  succession  of  sparks  induces  slow  combustion.  (W. 
Henry.) — Spongy  platinum  does  not  affect  a  mixture  of  ammoniacal 
gas  and  oxygen;  but  on  the  addition  of  detonating  gas,  the  platinum 
becomes  red-hot,  and  causes  the  ammonia  to  burn.  (Dbbereiner.) — At  a 
temperature  of  1 93'',  spongy  platinum  acts  on  a  mixture  of  equal  mea- 


422  NITROGEN. 

sure*  of  Ammoniacal  and  oxjgen  gasei,  water  being  alowlj  femiedf  and 
the  mtrogen  with  the  exoese  of  oxygen  left  in  the  free  «tate.  (W.  Henry, 
Ann.  Fhil,  25,  424.) — Platinum-buMck  immersed  in  ammoniaokl  gas  loaes 
its  power  of  inducing  combustion,  but  causes  the  ammonia  to  absorb 
oxjgen  from  the  air  and  thereby  to  be  decomposed  into  water  and 
nitrogen  gas;  but  the  action  is  feeble,  and  soon  ceases.  (Dobereiner, 
Ann,  Phartn.  1, 29.)-^.  A  mixture  of  ammoniacal  gas  with  hypochloroos 
acid  gas  explodes  yiolentl^,  with  separation  of  a  large  quantity  of 
chlorine.  Ammoniacal  gas  in  contact  with  a  concentrated  aqueous  solu- 
tion of  hypochlorous  aoid  emits  heat  and  a  yellow  light,  and  evolyes 
nitrogen  and  chlorine  gases.  Aqueous  ammonia,  gnbdnally  added  to 
an  aqueous  solution  of  hypochlorous  acid,  the  mixture  being  constantly 
kept  cool,  yields  nitrogen  gas  and  oily  drops  of  chloride  of  nitrogen; 
if  the  solutions  are  npidly  mixed,  or  if  they  are  highly  concentrated, 
heat  is  eyolved,  and  a  yiolent  disengagement  of  chlorine  and  nitrogen 
gases  takes  place.  (Balard.) — c.  Chloric  oxide  gas  yields  with  ammo- 
niacal gas  at  ordinary  temperatures,  nitrogen  gas,  sal-ammoniao,  and 
chlorate  of  ammonia.  (Stadion.  W-c2.  A  mixture  of  ammoniacal  gas  and 
nitrous  oxide—in  which  the  former  does  not  amount  to  less  thui  -f  of 
more  than  f  of  the  whole— explodes  by  the  electric  spark,  yielding,  when 
the  nitrons  oxide  gaa  is  in  excess,  water,  nitrogen,  oxygen,  and  a  small 
quantity  of  hyponitric  acid,  while  a  small  quantity  of  nitrous  oxide  renuuns 
undeoompoeed;  when  the  ammoniacal  gas  predominates,  tlie  products  are 
water,  nitrogen  gas,  and  hydrogen  gas,  together  with  a  small  quantity  of 
nndeoomposed  ammonia,  in  either  case  the  original  yolume  is  but  slightlf 
diminished.  (W.  Henry.)—  1  yolume  of  ammoniacal  gas  will  explo<b 
with  2*17  yolumes  of  nitrous  oxide,  but  not  with  2*386  yolumes  or  any 
greater  quantity;  eyen  when  the  latter  is  in  excess,  the  whole  of  the 
ammonia  is  not  burnt;  a  portion  is  resolyed  into  hydrogen  gas  and 
nitrogen  gas.  (Bischof,  iSchw.  43,  257.) — e,  Ammoniacal  gas,  mixed  with 
the  proper  proportion  of  nitric  oxide,  likewise  explodes  by  the  electric 
spark,  yielmng  similar  products.  (W.  Heni^.)  At  ordinary  tempera* 
tures,  a  mixture  of  equal  yolumes  of  ammoniacal  and  nitric  oxide  gases 
condenses,  in  the  course  of  a  month,  to  one  half  its  original  yolume,  with- 
out, howeyer,  undergoing  complete  decomposition ;  nitrogen  gas,  and 
probably  also  nitrous  oxide,  are  among  the  products.  Aqueous  ammonia 
in  contact  with  nitric  oxide  gas  likewise  produces  nitrous  oxide.  (Gay- 
Lussao.)— /.  Ammoniacal  gas  is  rapidly  and  yiolently  decomposed  at  or<u- 
nary  temperatures,  both  by  liquid  and  by  gaseous  hyponitric  acid,  with 
eyolution  of  nitric^  oxide  and  nitrogen  gases.  ^Dulong.)  Ammonia- 
cal gas  and  hyponitric  acid  yapour,  when  mixed  in  as  dry  a  state  as 
possible,  and  completely  freed  from  air,  undergo  mutual  decomposition, 
eyolying  great  heat,  and  yielding  nitrogen  gas,  water,  and  nitrite  of 
ammonia;  but  in  consequence  of  tne  formation  of  water  and  the  impossi- 
bility of  completely  excluding  the  air,  traces  of  nitrous  oxide  gas  and 
nitrate  of  ammonia  are  also  obtained.  (Soubeiran,  <7.  Fharm,  18,  329.) 
Probably  thus: 

4NH»  +  3N0*  «  NH*,  NO»  +  9HO  +  5N. 
[For  the  decomposition  of  ammonia  in  combination  with  sulphniio, 
selenio,  iodic,  periodic,  bromic,  hjrpochloric,  chloric,  perchloric,  nitrous 
and  nitric  acids,  refer  to  the  corresponding  salts.] 

— -a,  Ammoniacal  gas  is  decomposed  by  many  metallic  oxides,  frequently 
below  a  red-heat,  the  products  being  water,  nitrogen  gas,  a  greater  or 
smaller  quantity  of  reduced  metal,  and  occasionally  also  hyponitric  acid 


AMMONIA.  423 

(p.  888);  with  other  metallio  oxides  it  forms  water  and  a  nitride  of  the 
metal. 

3. — a.  With  ignited  charcoal,  ammonia  yields  hjdrocjanate  of  ammo* 
nia  and  nitrogen  gas.  (Glouet,  Langlois,  Ann,  Chim.  Fhys,  76,  111;  also 
J.  pr.  Chan.  23,  232.) 

2NH'  +  2C  =  NH»,  HC»N  +  2H. 

---5.  Transmitted  with  vapour  of  phosphorus  through  a  red-hot  tuhe,  it 
yields  phosphuretted  hydrogen  gas  and  nitrogen  gas  charged  with  vapour 
of  phosphorus;  similarly  with  vapour  of  sulphur,  it  forms  hydrogen  gas, 
nitrogen  gas,  and  a  crystallized  mixture  of  hydrosulphate  and  hydrosul^ 
phite  of  ammonia.  (Fourcroy.)  (For  Ob  decomposition  with  hisulphide 
of  carhon,  vid.  p.  205.) — c.  Iodine  decomposes  ammonia  at  ordinary 
temperatures,  but  only  in  contact  with  water,  yielding  iodide  of  nitrogen 
and  hydriodate  of  ammonia. 

4NH«  +  61  =  3(NH^  HI)  +  NK 

^~d.  Bromine  and  ammoniacal  gas  produce  hydrobromate  of  ammonia, 
heat  being  eyolved,  and  nitrogen  gas  set  free.  (Balard.) 

4NH»  +  3Br  =  3(NH»,HBr)  +  N. 

— ^.  In  chlorine  gas,  ammoniacal  gas  bums  at  ordinary  iemperatnres 
with  a  red  and  white  flame,  yielding  nitrogen  gas  and  hydrocmorate  of 
ammonia.     In  atomic  proportions : 

4NH3  +  3C1  =  3(NH»,HC1)  +  N. 

By  yolame :  8  volumes  of  ammoniacal  gas  and  3  volumes  of  chlorine 
gas  yield  sal-ammoniac  and  1  volume  of  nitrogen,  inasmuch  as  2  volumes  of 
ammoniacal  gas  give  up  their  3  volumes  of  hydrogen  to  the  3  volumes  of 
chlorine,  to  form  6  volumes  of  hydrochloric  acid  gas,  which  condense  with  6 
volumes  of  ammoniacal  gas  and  form  sal-ammoniac — ^while  from  the  2 
volumes  of  ammoniacal  gas  decomposed,  1  volume  of  nitrogen  gas  is  set  free. 
When  chlorine  gas  is  passed  in  successive  bubbles  into  concentrated  aqueous 
ammonia,  each  bubble  produces  a  slight  explosion  and  a  flash  of  light 
visible  in  the  dark.  (Simon,  Scher.  J.  9,  588.)  If  the  chlorine  is  made 
to  act  upon  ammonia  in  combination  with  a  strong  acid  and  dissolved  in 
water,  decomposition  takes  place  more  slowly,  and  the  nitrogen  separated 
from  the  ammonia  unites  with  a  portion  of  the  chlorine.  (Vid.  Uhloride 
of  Nitrogen.)^,  Chloride  of  sulphur,  under  certain  circumstances,  decom- 
poses ammonia,  great  heat  being  evolved  and  a  variety  of  products  formed. 
(Vid.  Sulphide  of  nitrogen  vnth  excess  of  sulphur ^  Ammonio'chloride  of 
sulphury  and  the  compound  of  Ammonio-^Moride  of  ndphur,  with  Ammonuh 
sulphide  of  nitrogen.) — Bi-chloride  of  selenium  decomposes  ammoniacal 
gas  with  the  aid  of  heat.  (H.  Rose,  Fogg.  52,  64.) 

Oombinations,  a.  Aqueous  Ammonia, — Liquid  Ammonia,  or  simply 
Ammonia-,  Spirit  of  Hartshorn,  Salmiakgeist,  dtsender  Salmiakgeist,  Spi- 
ritus  salis  ammoniaci  eausticus  s.  cum  eaUse  vivd  paratus, 

Ammoniacal  gas  is  absorbed  by  water  with  great  rapidity  and  con- 
siderable disengagement  of  heat.  Ice  rapidly  abwrbs  the  gas,  and  at  the 
same  time  liquefies,  with  reduction  of  temperature.  According  to  Davy, 
water  at  +  10°,  and  under  a  pressure  of  29*8  in.  absorbs  at  most  670 
times  its  volume  of  ammoniacal  gas,  or  nearly  half  its  own  weight ;  the 
specific  gravity  of  a  solution  of  this  strength  is  0*875.  According  to 
Dalton,  water  at  a  lower  temperature  absorbs  even  more  than  half  its 


424  NITROGEN. 

weight;  its  specific  gravity  then  falls  to  0-850.  At  24°  (75-2  P.)  lOO 
parts  of  water  absorh  8*41  parts,  and  at  55**  (131''  F,)  5*96  parts  of  am- 
moniacal  gas.  (Osann.)  6  measures  of  water  become  10  measures  when 
saturated  with  ammoniacal  gas.  (Thomson.)  1  measure  of  water,  bj 
absorbing  505  measures  of  ammoniacal  gas,  forms  a  liquid  occupying  1*5 
measures,  and  of  specific  gravity  0*900 ;  this  when  mixed  with  an  equal 
bulk  of  water,  yields  a  liquid  of  specific  gravity  0-9455;  consequently 
expansion  takes  place.  (Ure.) 

Preparation.  Into  the  glass  flask  a  (App.  50) — or,  in  preparing 
it  on  the  large  scale,  into  a  vessel  of  earthenware,  copper,  or  cast  iron, 
furnished  with  an  air-tight  cover — 1  part  of  sal-ammoniac  (or  sulphate 
of  ammonia  freed  by  gentle  roasting  from  empyreumatic  oil),  is  introduced 
in  lumps  and  covered  with  cold  milk  of  lime,  prepared  by  slaking  from  f 
to  1  part  of  lime  with  3  or  4  parts  of  water.  The  vessel  is  then  con- 
nected, as  in  the  preparation  of  hydrochloric  acid  (p.  322),  by  means  of 
three  bent  tubes,  (the  middle  one  being  a  Welter's  tube)  with  three 
Wonlfe*s  bottles,  the  first  of  which  contains  a  very  small  quantity  of 
water,  the  second  a  quantity  equal  in  weight  to  the  sal-ammoniac  employed, 
and  the  third  a  smaller  quantity.  The  first  two  bottles  are  surrounded 
with  cold  water  and  moistened  paper;  a  gentle  heat  is  then  applied,  and 
is  slowly  increased — so  that  the  mass  may  not  boil  over — till  from  one- 
fourth  to  half  the  water  in  the  vessel  a  has  distilled  over  into  the  first 
bottle  h.  In  the  first  bottle  a  weak  solution  of  ammonia  is  obtained, 
frequently  coloured  yellow  from  empyreumatic  oil  contained  in  the  sal-am- 
moniac ;  this  may  be  added  in  the  next  operation  to  the  sal-ammoniac 
and  milk  of  lime  in  the  vessel  a.  In  the  second  bottle  a  pure  and  con- 
centrated solution  of  ammonia  is  obtained;  if  required  to  be  perfectly 
saturated,  the  quantity  of  water  in  this  bottle  should  not  exceed  <|  of 
the  sal-ammoniac.  The  third  bottle  contains  very  weak  but  pure  am- 
monia. 

Distillation  from  a  retort  or  an  alembic  into  a  receiver,  yields  a  less 
pure  preparation. 

If  less  water  is  added  to  the  lime,  the  residue  consisting  of  chloride  of 
calcium  and  lime  adheres  more  firmly  to  the  bottom  of  the  vessel.  This 
solidification  of  the  mass  is  in  a  great  measure  obviated,  according  to 
Wiegleb  {Taachenh.  1781,  149),  by  the  addition  of  a  small  quantity  of 
common  salt.  The  sal-ammoniac  may  also  be  heated  with  finely  divided 
burnt  lime,  or  with  hydrate  of  lime  slaked  to  a  dry  powder  with  a  third 
of  its  weight  of  water.  Either  the  two  substances  are  mixed  in  the  state 
of  powder — whereby,  however,  a  large  Quantity  of  ammonia  is  lost  before 
the  mixture  is  introduced  into  the  vessel,  and  a  fused  mass  is  obtained  on 
heating,  which  as  it  cools  causes  the  glass  vessel  to  crack— or  the  sal-am- 
moniac is  placed  in  large  pieces  at  the  bottom  and  the  powdered  lime 
above  it;  in  the  latter  case  the  volatilized  sal-ammoniac  leaves  an  empty 
space,  by  which  the  vessel  is  preserved  from  injury.  This  method  is  so 
far  preferable,  that  for  a  given  amount  of  product,  smaller  vesseb  may  be 
employed,  and  the  operation  may  be  conveniently  carried  on  in  cast  iron 
retorts  very  slowly  heated.  But  a  portion  of  sal-ammoniac  volati- 
lizes, and  not  only  contaminates  the  liauid  in  the  first  bottle,  but  may 
also  stop  up  the  first  bent  tube,  and  thereuy  cause  a  dangerous  explosion. 
A  larger  quantity  of  empyreumatic  oil  also  passes  over  with  the  ammonia. 
Lastly,  the  resulting  chloride  of  calcium  obstinately  retains  a  portion  of 
the  ammonia,  and  consequently  diminishes  the  product. 


AMMONIA. 


425 


Impurities  in  aqueous  Ammonia:  Carhonaie  of  Ammonia.  Occur  when 
the  lime  used  in  the  preparation  contains  a  large  quantity  of  carhofiic  acid, 
or  the  solution  is  afterwards  exposed  to  the  air.  Renders  lime  water 
turbid,  at  least  on  the  application  of  heat. 

Chloride  of  Ammonium;  carried  over  mechanically  or  in  the  form  of 
vapour,  into  the  first  bottle.  The  liquid  supersaturated  with  nitric  acid, 
gives  a  cloud  with  solution  of  silver;  lea7es  sal-ammoniac  on  evaporation. 

Lime  and  Chloride  of  Calcium;  mechanically  carried  over  into  the 
first  vessel.     Left  behind  on  evaporating  the  solution. 

Copper  and  Tin;  when  the  still  heads,  condensing  tubes,  or  bent  tubes 
are  made  of  copper.     The  liquid  is  turned  brown  by  sulphuretted  hydro* 

fen,  after  being  saturated  with  hydrochloric  acid.     The  oxides  are  left 
ehind  on  evaporation. 

Empyreumaiic  oil;  from  the  sal-ammoniac.  Imparts  a  yellow  colour 
and  characteristic  odour. 

Properties.  Colourless,  transparent  liquid.  Specific  gravity  between 
I'OOO  and  0*850,  depending  upon  the  amount  of  ammonia  present. 
When  concentrated,  it  does  not  freeze  till  cooled  to  between  —  36° 
and  —41°  (—36°  and  —42°  P.);  it  then  forms  brilliant  flexible  needles; 
at  —40°  (—60°  F.),  it  solidifies  to  a  grey  gelatinous  mass,  almost  desti- 
tute of  odour.  (Fourcroy  &  Vauquelin.)  Smells  like  ammoniacal  ga«, 
and  has  a  sharp,  burning,  urinous  taste.  Loses  the  greater  part  of  the 
ammonia  at  a  temperature  below  100°.  According  to  Thomson,  the  gas 
is  entirely  expelled,  even  at  55°.  (see,  however,  Osann's  statement,  p.  424.) 
On  dissolving  hydrate  of  potash  in  aqueous  ammonia,  bubbles  of  ammo- 
niacal gas  are  disensaged,  which  are  again  absorbed  by  the  upper  portion 
of  the  liquid.  (Waller.) 

Amount  of  real  Ammonia  in  Aqueous  Ammonia  of  different  Densities, 


1 

According 

to  Sir  H.: 

According  to  Dalton    { 

Davy            1 

According  to  Ure  {Schw,  32, 

58). 

(N,  Sytt,  2, 

230). 

{Elements 

1,241). 

Sp. 

Amm. 

Boiling 

Amm. 

Amm. 

Amm. 

8T- 

pep  c. 

point. 

Sp.gr. 

per  c. 

Sp.gr. 

per  c. 

Sp.gr. 

per  c. 

0-85  .. 

..  35-3  . 

...  -4  ° 

0-8750  .. 

..  32-3* 

0-8914  .. 

..  27-940 

0-9363  .. 

.  15-900 

0-86  .. 

..  32-6  . 

...   +3-5 

0-8857  .. 

..  29-25 

0-8937  .. 

..  27-633 

0*9410  .. 

.  14-575 

0-87  . 

..  29-9  . 

...     10 

0-9000  .. 

..  26 

0-8967  .. 

..  27038 

0-9455  .. 

.  13-250 

0-88  . 

..  27-3  . 

...     17 

0-9054  .. 

..  25-37* 

0-8983  .. 

..  26-751 

0-9510  .. 

..  11-925 

0-89  . 

..  24-7  . 

...     23 

0-9166  .. 

..  22-07 

0-9000  .. 

..  26-500 

0-9564  .. 

..  10-600 

0-90  . 

..  22-2  . 

...    30 

0-9255  .. 

..  19-54 

0-9045  .. 

..  25-175 

0-9614  .. 

..     9-275 

0-91  . 

..  19-8 

...    37 

0-9326  .. 

..  17-52 

0-9090  .. 

..  23-850 

0-9662  .. 

..     7-950 

0-92  . 

..  17-4 

...     44 

0-9385  .. 

..  15-88 

0-9133  .. 

..  22-525 

0-9716  .. 

..     6-625 

0-93  . 

..  15-1 

...     50 

0-9435  .. 

..  14-53 

0-9177  .. 

..  21-200 

0-9768  .. 

..     5-500 

0-94  . 

..  12-8 

...     57 

0-9476  .. 

..  13-46 

0-9227  . 

..  19-875 

0-9828  .. 

..     3-975 

0-95  . 

..  10-5 

...    63 

0-9513  .. 

..  12-40 

0-9275  .. 

..  18-550 

0  9887  .. 

..     2-650 

0-96  . 

..     8-3 

...     70 

0-9545  .. 

..  11-56 

0-9320  . 

..  17-225 

0-9945  .. 

..     1-325 

0-97  . 

..     6-2 

...     79 

0-9573  .. 

..  10-82 

0-98  . 

..     4-1 

...     87 

0-9597  .. 

..  10-17 

0-99  . 

...     20 

...     92 

0-9616  .. 
0-9632  .. 

..     9-6 
..     9-5* 

In  Davy's  tables  the  three  numbers  marked  with  asterisks  were 
determined  by  experiment,  the  rest  by  calculation.  (Richter's  tables, 
Slochiometrie,  3,  233.) 


426  NITROOBN. 

Ammonia  likewue  eombinM*.— ^.  With  Phosphorio  Oxide.*— «.  With 
Bisulphide  of  Carbon.— c2.  With  Sulphide  of  Phosphorns.^-^.  With  Iodine  t 
—f.  With  Phosgene.-*^.  With  Chloride  of  Boron.— iA.  With  Chloride  of 
Phosphorus. — i.  With  Chloride  of  Sulphur. — h.  With  Carbonate  of  Chlo- 
ride of  Sulphur. — I.  With  Fluoride  of  Boron. 

m.  With  acids  with  which  it  fomu  the  AmfMmva/cal  SaU».  Ammonia 
is  capable  of  uniting  with  the  hydrogen  acids  without  the  interrention  of 
water.  These  compounds  maj  be  regarded  in  three  different  ways: 
— 1.  According  to  the  old  yiew,  they  are  compounds  of  hydrogen  aoids 
with  ammonia:  thus^  sal-ammoniao  is  NH',  HCl.-^2.  According  to 
Kane,  they  are  compounds  of  hydrogen  acicLBi  with  hydramide:  HAd, 
HCl. — 3.  Accordiug  to  Berxelius,  thej  are  compounds  of  ammonium 
(a  substance  resembling  the  metals  in  many  respects,  and  contain- 
ing 1  atom  of  nitrogen  and  4  atoms  of  hydrogen,)  with  different  salt- 
radicals.  According  to  this  view,  sal-ammoniac  is  NH^Cl,  corresponding 
to  KCl,  NaCl,  &c.,  the  crystalline  form  of  which  it  also  possesses.  When 
ammonia  is  added  to  a  solution  of  chloride  of  glucinum,  the  latter  theory 
supposes  that  the  precipitation  of  the  metallic  oxide  is  accompanied  by 
decomposition  of  water. 

GCl  +  HO  +  NH>  =  NH*a  +  GO. 

With  the  oxygen  acids,  howeyer,  ammonia  combines,  for  the  most 
part,  only  in  presence  of  water,  1  atom  of  which  the  salt  obstinately 
retains,  so  that  it  cannot  be  expelled  by  heat  without  decomposition  of 
the  salt  itself.  This  characteristic  behayionr  is  explained  by  Berselius 
in  the  following  manner:  The  ammonium,  NH^,  is  conyerted  by  uniting 
with  1  atom  of  oxygen  into  oxide  of  ammonium,  NH^O,  which  like  potassa 
and  other  salifiable  bases  is  capable  of  combining  with  oxygen  acids. 
According  to  this  yiew,  sulphate  of  ammonia  is  not  NH',  SO'-f  HO  but 
NH^O,  SO".  Kane  regards  ammonia,  HAd,  as  a  salifiable  base  isomor- 
phous  with  HO,  MgO,  MnO,  ZnO,  FeO,  CoO,  NiO,  CuO,  in  short  with  the 
bases  of  Graham's  Magnesia  aroup.  In  many  instances,  two  of  these 
bases — 1  atom  of  each — are  tound  intimately  combined  with  I  atom  of 
acid.  Thus,  according  to  Graham,  on  heatmg  white  yitriol,  ZnO,  SO' 
-h  7Aq,  to  a  temperature  of  100^,  there  remains  a  compouudof  1  atom  of 
sulphuric  acid  with  1  atom  of  oxide  of  zinc  and  1  atom  of  water  =  ZnO, 
HO,  SO',  from  which  the  water  can  only  be  expelled  at  a  temperature 
approaching  238^.  These  salts,  vehich  contain  1  atom  of  acid  to  1  atom 
of  oxide  and  I  atom  of  water,  are  the  analogues  of  the  ordinary  ammo- 
niacal  oxygen-acid  salts,  the  metallic  oxide  being  replaced  by  hydra- 
mide; sulphate  of  ammonia  for  instance  is:  HAd,  HO,  SO'. 

Most  of  the  ammoniacal  salts  may  be  formed  by  bringing  ammonia  or 
carbonate  of  ammonia  directly  in  contact  with  acids. 

Although  the  affinity  of  ammonia  for  acids  is  less  than  that  of  the 
other  alkalis,  it  yet  neutralizes  them  more  completely.  The  ammoniacal 
^alts  haye  generally  a  pungent,  saline,  somewhat  urinous  taste. 

All  the  ammoniacal  hydracid  salts,  and  likewise  carbonate  of  ammo- 
nia, are  yolatilized  by  heat  without  decomposition;  the  other  oxygen-acid 
salts  when  heated  either  evolve  the  ammonia  undecomposed  and  leave 
the  acid  in  its  entire  state  (phosphoric  acid),  or  the  hydrogen  of  the 
ammonia  combines  wholly  or  in  part  with  the  oxygen  of  the  acid — water 
being  formed  and  nitrogen  gas  set  free  (as  with  sulphuric  acid).  Many 
ammoniacal  oxygen  salts^  and  even  sal-ammoniac,  when  exposed  to  the 


s 


AMMONU.  427 

air  at  ordinal^  temperatoreS;  and  Btill  more  on  the  evaporation  of  their 
aqueoiu  solutions,  lose  a  portion  of  ammonia,  so  that  the  residue  exhibits 
an  aoid  reaction,  Ammoniaoal  salts  dissolved  in  water  and  treated  with 
chlorine  gas  yield  either  hydrochloric  acid  and  nitrogen,  or,  if  the  salt 
contains  a  powerful  acid,  hydrochloric  acid  and  chloride  of  nitrogen. 
(Dulong.)  An  aqueous  solution  of  hypochlorous  acid  yields  with  dry 
ammoniacal  salts,  water,  chloride  of  nitrogen  and  nitrogen  gas,  while 
nitrogen  and  chlorine  remain  in  solution.  (Balard.)  Fixed  alkalis,  oxide 
of  lead,  &c.,  rubbed  up  with  ammoniacal  salts,  especially  if  a  small 
quantity  of  water  is  present,  disengage  ammonia,  which  may  be  recog^ 
nized  by  its  odour,  by  the  red  colour  which  it  imparts  to  turmeric  paper, 
and  by  the  cloud  which  a  glass  rod  moistened  with  hydrochloric  acid 
produces  when  held  over  the  mixture.  Magnesia  expels  only  half  the 
ammonia  and  forms  a  double  salt.  (Sch,  96.) 

All  ammoniacal  salts  dissolve  in  water  and  for  the  most  part  with 
facility.  A  solution,  when  not  too  dilute,  gives  a  crystalline  granular 
precipitate  with  concentrated  sulphate  of  alumina  (ammonia  alum),  with 
bichloride  of  platinum  (chloride  of  platinum  and  ammonium),  and,  often 
after  a  long  time  only,  with  tartaric  aoid  (bitartrate  of  ammonia).  Only 
the  most  concentrated  solutions  of  ammoniacal  salts  give  a  precipitate 
with  perchloric  acid,  hydrofluosilicic  acid,  and  carbasotic  acid.  Sal-am« 
moniac  dissolved  in  so  much  water  that  1  part  of  ammonia  is  contained 
in  100  parts  of  the  liquid  yields  an  abundant  precipitate  with  solution  of 
platinum ;  with  200  parts  of  water,  a  slight  precipitate ;  with  400  parts, 
very  slight  indeed;  and  with  800  parts  of  water,*  a  scanty  precipitate 
after  a  lapse  of  12  hours.  (Lassaigne,  J,  Chim,  Med,  8,  528.)  Dilute 
alcohol  heated  with  pounded  ammoniacal  salts  and  then  set  on  fire, 
bums  with  a  blue  or  violet  flame. 

The  ammoniacal  salts  form  numerous  double  salts  with  the  salts  of 
soda,  magnesia,  alumina,  and  the  oxides  of  manganese,  zinc,  cobalt,  nickel, 
copper,  platinum,  palladium,  rhodium,  iridium,  and  others. 

The  compounds  of  anhydrous  oxygen  acids  with  ammonia  may  be 
distinguished,  according  to  H.  Roses  nomenclature,  as  Afn/mon^alt9 
{Ammonsalze).     [Vide  Carbonate,  Sulphite,  and  Sulphate  of  Ammon,'] 

n.  Aqueous  ammonia  forms  solutions  with  numerous  heavy  metallic 
oxides,  as  with  the  sesqui-oxide  of  chromium,  the  oxides  of  tellurium, 
zinc,  and  cadmium,  binoxide  of  tin,  the  protoxides  of  lead,  iron,  tin, 
cobalt  and  nickel,  the  dinoxide  and  protoxide  of  copper,  and  with  oxide 
of  silver;  with  the  oxides  of  vanadium,  uranium,  antimony,  mercury, 
silver,  gold,  platinum,  and  rhodium,  ammonia  likewise  forms  solid  com* 
pounds,  some  of  which  are  explosive. 

o.  With  many  Anhydroue  Oxygen-scUts  of  Metallic  Oxidee,  which 
absorb  ammonia  abundantly  and  in  atomic  proportion,  the  combination 
being  frequently  attended  with  rise  of  temperature.  The  ammonia  in 
these  compounds  replaces  the  water  of  crystallization;  when  heated, 
they  evolve  the  ammonia  wholly  or  in  part,  and  are  generally  decom- 
posed by  water.  ^(H.  Rose,  Po^^.  20,  147). 

p.  With  many  metallic  iodides,  bromides,  and  chlorides,  which,  some- 
times by  exposure  to  ammoniacal  gas — the  absorption  being  frequently 
attended  with  disengagement  of  heat — sometimes  m  the  wet  way,— com- 
bine, according  to  their  nature,  with  ^,  1 ,  2,  or  3  atoms  of  ammonia^ 
HAd,  which  in  these  compounds  takes  tne  place  of  water  HO.  Many  of 
these  compounds  lose  their  ammonia  even  when  exposed  te  the  air;  others, 
but  not  all,  give  it  np  when  heated :  in  some  cases,  the  application  of 


428  NITROGEN. 

beat  causes  the  sublimation  of  hjdriodate^  hydrobromate^  or  hydrochlo* 
rate  of  ammonia.  Water  decomposes  the  greater  number  of  these  com- 
pounds, either  dissolring  the  haloid  salt  and  separating  the  ammonia 
(chloride  of  calcium),  or  in  other  cases  precipitating  the  metal  in  the 
state  of  oxide.  Some  of  them  howeyer  dissolve  in  water  without  being 
decomposed  ;  and  the  solution  frequently  contains  a  portion  of  the  ammo- 
nia in  a  condition  similar  to  that  in  which  it  exists  in  anhydrous  sulphate 
of  ammon,  so  that  solution  of  platinum  precipitates  only  part  of  the  am- 
mouia  from  it.  (Vid.  Faraday,  H.  Rose,  Persoz,  Rammelsberg,  in  the 
memoirs  referred  to  on  pase  370.) 

q.  With  Fluoride  of  Silicium.— r.  With  Metallic  Cyanides.— <.  With 
many  other  organic  compounds. 


C.    Ahhoxium.    NH*. 

Kane's  Suhamidide  of  Hydrogen^^WKA, 

Not  known  in  the  separate  state.  Exists  in  the  ammoniacal  amalgam, 
combined  with  mercuiy ;  also  according  to  Berzelius,  in  the  ammoniacal 
salts,  in  combination  either  with  the  radical  of  the  hydrogen  acid,  or  as 
oxide  of  ammonium  with  the  oxygen  acid. 

Theories  relating  to  Ammonia. 

1.  Old  Theory: — Ammonia,  NH^,  is  an  alkali.  It  combines  directly 
with  hydrogen  acids ;  thus,  with  hydrochloric  acid  it  forms  hydrochlorate 
of  ammonia  =  NH^,  HCl.  With  oxygen  acids,  ammonia  unites  for  the 
most  part  only  when  an  atom  of  water  is  present,  in  which  case  the  com- 
bination is  perhaps  rendered  possible  by  the  circumstance  of  the  water 
containing  hydrogen  like  ammonia,  and  oxygen  like  the  ox-acid.  Accord- 
ing to  this  view,  sulphate  of  ammonia  is  NH',  HO,  SO*.  The  union  of 
1  atom  more  of  hydrogen  with  the  ammonia  forms  a  compound,  NH^, 
which  is  known  only  in  the  form  of  the  ammoniacal  amalgam. 

2.  Ammomumrtheory  of  Berzelius, — Formerly  proposed  by  Ampere 
(Ann.  Chim.  Phys,  2,  6)  but  first  consecutively  followed  out  by  Berzelius. 
Ammonia  doesjnot  combine  directly  with  hydrogen  acids,  but  i8|convreted, 
by  uniting  with  the  hydrogen  of  the  acid,  into  ammonium,  NH*,  which 
then  unites  with  the  radical  of  the  acid.  Thus,  with  hydrochloric  acid 
ammonia  yields  chloride  of  ammonium  =  NH^Cl.  Ammonium,  NH*,  is  a 
compound  metal,  that  is  to  say  a  compound  substance  having  the  chemi- 
cal relations  of  a  metal:  when  1  atom  of  oxygen  unites  with  it  (or, 
what  is  the  same  thing,  1  atom  of  water,  HO,  with  1  atom  of  NH*), 
a  salifiable  metallic  oxide,  the  oxide  of  ammonium,  is  produced  capable 
like  oxide  of  potassium  KO — with  which  it  is  isomorphous— of  forming 
salts  with  oxygen  acids.  According  to  this  view,  sulphate  of  anmionia 
is  more  properly  to  be  regarded  as  sulphate  of  oxide  of  ammonium  = 
NH*0,  SO*. 

This  theory  presents  the  following  advantages: — 1.  It  explains  the 
great  similarity  in  physical  and  chemical  characters,  which  the  hydro- 
chlorate  of  ammonia  (considered  as  chloride  of  ammonium)  bears  to  chlo- 
ride of  potassium  and  other  metallic  chlorides,  that  of  iodide  of  ammonium 
to  the  metallic  iodides,  &c. — 2.  If  the  existence  of  the  hydrogen-acid 
salts  is  denied  (pp.  10 — 13)  this  view  does  away  with  the  exception  which 


AMMONIUM.  429 

the  componnds  of  ammonia  with  the  hydrogen  ^cida  would  otherwise 
create.— -3.  The  theory  sufficiently  explains  why  the  oxygen  acids  gene- 
rally unite  with  ammonia  only  when  water  is  present^  the  water  having 
first  to  convert  the  ammonia  into  oxide  of  ammonium,  which  then  forms 
the  salifiable  base. 

On  the  other  hand,  the  following  considerations  must  be  taken  into  ac- 
count.— 1.  It  is  improbable  that  ammonia  should  be  capable  of  separat- 
ing the  hydrogen  from  the  chlorine  in  hydrochloric  acid ;  at  all  events 
such  separation  supposes  an  extraordinary  affinity  of  chlorine  for  ammo- 
nium.— 2.  If  ammonia  is  not  converted  into  a  base — the  oxide  of  ammo- 
nium— unless  it  takes  up  an  atom  of  water,  it  is  not  very  easy  to  see  in 
what  light  ammonia  is  to  be  regarded,  seeing  that  even  in  the  anhydrous 
state  it  reddens  turmeric,  and  has  an  alkaline  taste  and  other  alkaline 
properties. — 3.  Phosphuretted  hydrogen  PH'  has  a  composition  similar 
to  tnat  of  ammonia  NH',  and  forms  both  with  hydriodic  acid  and  hydro- 
bromic  acid,  crystalline  compounds  similar  to  those  of  ammonia.  Hence 
in  accordance  with  the  ammonium  theory,  the  hydriodate  of  phosphuret- 
ted hydrogen,  must  be  regarded  as  PH*,  I,  and  the  existence  of  a  hypothe- 
tical compound  PH^  allowed;  or  the  compound  must  be  viewed  as  PH^,HI, 
and  by  tnis  dissimilarity  in  the  formula,  the  similarity  in  composition 
is  lost  sight  of,  whilst  that  of  the  physical  and  chemical  characters  is  con- 
siderable.— 4.  It  is  remarkable  that  the  oxide  of  ammonium,  NH^O,  can- 
not be  isolated. — 5.  Whether  ammonium,  if  chemists  could  succeed  in 
preparing  it,  would  exhibit  a  metallic  appearance,  must  for  the  present 
remain  undecided. 

3.  Kane's  Amid'iheory,  Amidogen,  H*N,  is  a  feeble  salt-radical ; 
from  its  combiuation  with  1  atom  of  hydrogen,  results  Ammonia^ 
Hydramide,  or  Amide  of  Hydrogen,  =  HAd.  This  compound  is  a 
base  similar  to  HO  and  belonging  to  Graham's  magnesian  group  of 
isomorphous  elements:  (CaO,  MgO,  MnO,  ZnO,  FeO,  CoO,  NiO,  CuO.)  It 
unites  as  such  with  the  hydrogen  acids,  yielding  for  instance  with  hydro- 
chloric acid:  HAd, HCl.  It  forms  similar  compounds  with  metallic 
chlorides,  &c.,  in  which  it  replaces  HO.  It  also  combines  with  a  few 
anhydrous  oxygen  acids,  for  instance,  with  sulphuric  acid,  forming  HAd, 
SO',  or  according  to  the  binary  salt  theory  (pp.  14....  16)  H,  SO'Ad. 
Ammonium,  according  to  this  view,  is  a  compound  of  2  atoms  of  hydrogen 
with  1  atom  of  amidogen  =  H^Ad,  or  a  Stihamidide  of  hydrogen.  The 
oxide  of  ammonium,  NH*0,  of  Berzelius,  consists,  according  to  Kane,  of 
two  salifiable  bases,  namely  water  and  amide  of  hydrogen,  =  HAd,  HO. 
In  the  ordinary  ox-acid  ammoniacal  salts,  thereK>re,  1  atom  of  acid  is 
combined  with  1  atom  of  ammonia  and  1  atom  of  water,  that  is  to 
say,  with  2  atoms  of  base.  According  to  this  view,  sulphate  of  ammo- 
nia is  HAd,  HO,  SO'.  Whilst  HAd  alone  is  isomorphous  with  the  mem- 
bers of  the  magnesia  group,  HAd,  HO  is  for  the  most  part  isomorphous 
with  potash  and  soda.  (I.,  90.)  This  supposition  is  supported  by  the 
fact  that  CaO,  HO  in  Scolezite  replaces  NaO  in  Natrolite  (I.  89,  23). 
Whence  it  appears  to  follow  that  KO  or  NaO  may  be  replaced  by  HAd, HO, 
or  CaO,  HO;  in  short,  that  2  atoms  of  a  base  belonging  to  the  magne- 
sian group  replace  1  atom  of  potash  or  soda  in  combination.  The  salts 
of  zinc,  nickel,  copper,  &c.,  cyrstallized  from  an  aqueous  solution,  are  also 
analogous  to  the  ordinary  ammoniacal  salts  in  this  respect,  that  they  con- 
tain 1  atom  of  water  in  a  state  of  intimate  combination  (p.  42G). 

Whatever  may  be  the  fate  of  these  two  theories,  which  no  doubt  have 
some  truth  in  them,  the  following  facts  may  be  regarded  as  established: 


430  NITROGEN. 

NH'  is  a  compound  analogooB  to  oxygen,  chlorine,  iodine,  Aa.;  NH'  is  a 
Balifiable  base,  probably  isomorpbons  with  water  and  with  the  bases  of 
themagnesian  gronp;  NH*  behaves  like  a  metal;  'NH%  HO  or  NH^O 
is  likewise  a  salifiable  base  isomorphoos  with  potash  and  soda.  > 

NiTROOBN  AND  GaBBON, 

[Cyanogen  and  the  compounds  connected  with  it  will  be  discussed 
with  the  Organic  Compounds.] 

Carbonate  of  Ammonia. 

a.  Anhydrous  Mono-carbonate  of  Ammon, — In  whatever  pronortions 
ammoniacal  gas  and  carbonic  acid  gas  (both  perfectly  diy)  are  oronght 
together,  they  condense  slowly  and  with  disengagement  of  heat,  in  the 
proportion  of  1  volume  of  carbonic  acid  to  2  volumes  of  ammonia. 
(6ay-Lussac,  J.  Davy,  H.  Rose.) — 1.  A  mixture  of  1  volume  of  carbonic 
acid  gas  with  2  volumes  of  ammoniacal  gas  is  passed  through  a  number 
of  glass  tabes  cooled  down  to  a  very  low  temperature.  In  these  tubes 
the  salt  collects  in  the  form  of  a  sublimate;  they  are  afterwards  cat  in 
pieces  and  the  salt  quickly  extracted. — 2.  A  mixture  of  anhydrous  sul- 
phate of  ammon  and  carbonate  of  soda  is  sublimed  in  such  a  manner 
that  no  moisture  can  have  access  to  it.  (H.  Rose.) 

White  mass  which  smells  of  ammonia  (H.  Rose);  has  a  powerful  alka- 
line action ;  volatilizes  at  a  temperature  just  above  60^,  and  again  condenses 
below  60^.  (J.  Davy.)  (For  the  specific  grayity  of  the  vapour  vid,  I. 
280.) 

Calculation.  H.  Rose.  Vol.      Sp.  gr. 

NHS  17  43-59  44*69  Ammoniacal  gaa  ....  {  ....  0*3929 

CO*  22  56*41  55-45  Carbonic  acid  gaa....  )  ....  2*5084 

NH»,CO« 39  10000  100*14  Vapour 1  ....     -9013 

Hence  the  two  gases  combine  without  condensation.  (J.  Davy;  Bineau, 
Ann,  Chim,  Phys,  67,  240 ;  H.  Rose.)  The  salt  may  be  repeatedly  sub- 
limed without  change  of  composition.  (H.  Rose.) 

Aqueous  acids  cUsengage  carbonic  acid  from  the  salt,  and  fixed  alkalis 
liberate  ammonia.  (H.  Rose.)  Chloride  of  calcium  precipitates  carbonate 
of  lime  from  the  aqueous  solution,  without  causing  any  evolution  of  gas. 
(J.  Davy.)  Dry  chlorine  gas  converts  the  anhydrous  salt  after  some 
days  into  sal-ammoniac,  carbonic  acid,  and  nitrogen  gas.  The  vapour  of 
anhydrous  sulphuric  acid  passed  over  it,  expels  carbonic  acid  and  pro- 
duces anhydrous  sulphate  of  ammon.  When  heated  in  sulphurous  acid 
gas,  it  yields  on  orange-coloured  sublimate  of  anhydrous  sulphite  of  am- 
mon. It  is  decomposed  in  hydrochloric  acid  gas,  on  the  application  of  heat, 
yielding  carbonic  acid  and  sal-ammoniac ;  heated  in  hydrosulphuric  acid 
gas  it  forms  hydrosulphate  of  ammonia.  If  not  kept  perfectly  free  from 
moisture,  it  appears  to  be  converted  into  b.  (H.  nose.)  A  solution  of 
this  salt  in  water  behaves  like  a  solution  of  the  following  salts  mixed  with 
a  proportional  quantity  of  ammonia.  (Mitscherlich.) 

b,  Hydraied  Mono-Carbonaie  of  Ammonia, — 1.  Ordinary  sesqui-car- 
bonate  of  ammonia,  or  a  mixture  of  sal-ammoniac  and  carbonate  of  soda,  is 

fently  heated  in  a  retort,  the  neck  of  which  is  prolonged  by  a  glass  tube 
ipping  into  mercuiy;  pure  carbonic  acid  is  first  disengaged,  and  after- 
wards the  compound  b  sublimes  and  is  deposited  at  the  end  of  the  neck. 


AMMONIA.  431 

(J.  Dary,  H.  Rose.)  Towards  the  eod  of  the  prooess^  other  salts  are  sub* 
limed. — 2,  The  commercial  salt  is  heated  in  alcohol  or  ether^  and  the  sub* 
limed  salt  h  is  freed  by  evaporation  in  yacao  over  oil  of  yitriol  from 
adhering  alcohol  or  ether.  (Hiinefeld,  J.  pr.  Chan.  7,  25;  H.^  Rose.) — 
Crystalline;  may  be  repeatedly  sublimed  without  decomposition.  De- 
liquesces in  the  air^  dissolyes  readily  in  water,  but  cannot  be  recoyered 
from  the  solution;  because,  eyen  at  ordinary  temperatures  in  vacuo,  am- 
monia is  disengaged  from  it  and  an  acid  salt  obtained.  A  verjr  dilute 
solution  does  not  precipitate  chloride  of  calcium  till  after  some  time— a 
circumstance  which  is  characteristic  of  the  normal  carbonate  of  ammonia. 
(H.  Rose.) 

Calculatioii.  H.  Rote. 

2NH»     84    39-08  89-27 

2CO«  44  50-68  5009 

HO     9    10-34  10-64 

2NHa,HO,2CO»  87 100*00  100-00 

It  must  be  regarded  as  NH^,  C0«  +  NH»,  HO,  CO«. 

c.  Five-faurthg-CarhoiKUe  of  Ammonia, — «.  With  4  atoms  of  toater. — 
Sublimes  on  slowly  heating  the  ordinary  sesqui-carbonate,  and  is  deposited 
in  crystal-line  scales  in  the  arch  of  the  retort. 

ft  With  5  atoms  of  water. — 1.  Formed  by  subliming  the  variety  of 
sesqui-carbonate  of  ammonia  which  contains  5  atoms  of  water. — 2.  By 
heating  the  salt  a  in  a  retort  till  it  fuses  to  a  clear  liquid;  carbonic  acid 
is  then  evolved,  and  the  salt  0  sublimed,  while  the  fused  residue  solidifies 
on  cooling,  and  forms  salt  y, 

y.  With  12  atoms  of  water.  (H.  Rose.) 

Calcnlatioii.      H.  Rose.  Calculation.     H.  Rose.  Calculation.        H.Rose. 

4NH»....  68....31-78....31-13  68....30-49....30-53  68....23-78....22-70 

5CO«....110....51-40  ...52-92  110....49-33....48-56  110....88-46....88'31 

4HO  ....  36....16-82  ...IS'OS  5H0    45....20-18....20-91  12  HO  108....87-76  ...88-99 

a.    214  100-00  10000        p.     223  100*00  100-00         y.      286  10000  10000 

The  salt  a  is  considered  by  H.  Rose  as  3  (NH»,  CO«)-hNH*0,  2C0", 
3H0;  it  may  also  be  regarded  as  2(NH»,  HO,CO»)  +  2NH>,  2H0,  300^ 

d.  SesqmearhonaU  of  Ammonia. — ».  With  2  atoms  of  water.  Sal 
Alkali  volatile,  Sal  volatile  salis  ammoniaci;  Commercial  Carbonate  of 
Ammonia;— M  obtained  by  the  dry  distillation  of  bones,  hartshorn,  &c. 
and  contaminated  with  empyreumatic  animal  oil :  Volatile  salt  of  Harts- 
horn, fluchtiges  Hirschhornsalz,  Sal  volatile  Comu  Otfrvt.— Obtained  by 
heating  a  mixture  of  1  part  of  sal-ammoniac  (or  sulphate  of  ammonia) 
and  2  parts  of  chalk,  to  incipient  redness.  On  the  small  scale,  a  glass 
retort  with  glass  receiver  is  employed ;  on  the  large  scale,  an  earthen- 
ware or  cast-iron  retort  with  an  earthenware  or  leaden  receiver,  which, 
when  tolerably  well  filled  by  several  distillations,  is  broken  or  cut  in  two. 

3(CaO,CO»)  +  3(NH»,HC1)  «  3CaCl  +  (2NH*,  2HO,  3CO*)  +  NH»  +  HO. 
The  atom  of  NH'  and  the  HO  volatilize  at  the  commencement,  after  which 
the  salt  d  distils  over  in  the  form  of  a  liquid  into  the  receiver,  where  it 
rapidly  solidifies.  (Vid.  0.  Figuier,  J.  Pharm.  17,  237;  also  N.  Tr.  24,  1, 
252.) — The  salt  of  hartshorn  obtained  by  the  destructive  distillation  of 
animal  matter,  may  be  also  purified  from  the  combustible  oil  which  it 
contains,  by  subliming  it  once  or  twice  with  1^  times  its  weight  of 
animal  charcoal,  in  cast-iron  vessels  over  which  glass  receivers  are  inverted. 
By  repeated  sublimation,  however^  the  salt  acquires  a  difierent  compo- 


432  NITROOEN. 

Bition^  a  mizinre  of  the  salts  h  and  c  being  formed ;  on  this  account  the 
commercial  salt  frequently  contains  excess  of  ammonia. 

Impurities:  Hypotulphite  of  Ammonia.  This  impurity  occurs  -when 
sulphate  of  ammonia  or  sal-ammoniac  containing  sulphate  of  ammonia  is 
employed  in  the  preparation.  The  salt  neutralized  with  acetic  acid  gives 
a  white  precipitate  which  rapidly  turns  black  on  the  addition  of  nitrate 
of  silver.  (Pfaff,  Schw.  55,  237 .y—Sulphale  of  Ammonia;  from  the  same 
sources.  The  salt  neutralized  with  hydrochloric  acid  precipitates  chloride 
of  barium. — Sal-ammoniac,  The  salt  dissolved  in  pure  nitric  acid,  gives 
a  white  precipitate  with  solution  of  silver. — Lead.  From  the  employ- 
ment of  leaden  receivers.  Imparts  a  grey  colour  to  that  portion  of  the 
salt  which  has  been  in  contact  with  the  receiver.  The  salt  boiled  with 
a  slight  excess  of  dilute  nitric  acid  yields  a  solution  which  gives  the 
reactions  of  lead. — Lime  and  Chloride  of  Calcium;  from  mechanical  im- 
purities ;  remain  like  other  fixed  substances,  in  the  form  of  a  permanent 
residue,  when  the  salt  is  volatilized. 

Transparent  fibrous  mass. 

H.Rose. 
Calculation.  Ure.  J.  Davy.         12  3         Kirwan. 

2NH*....  34  ....  28-81  30-5  27*39  ....  2866  ....  307  24 

.3CO«....  66  ....  55-93  54*5  5458  ....  50-55  ....  534  ....  56*23  ....  52 

2HO  ....  18  ....  15*26  150  1803  ....  20*79  ....  15*9  24 

dTo       118       10000  1000  100^00       100*00       1000  100 

The  varieties  1  and  2  of  the  commercial  salt  examined  by  H.  Rose, 
contained  portions  of  the  salt  c,  /?.  The  salt  may  be  regarded  as  2NH^ 
2HO,3CO»;  or,  according  to  H.  Rose,  as  NH^CO»^-NH^2C0^2HO. 
The  decomposition  which  the  salt  undergoes  by  exposure  to  the  air, 
favours  the  latter  view. 

When  the  vapour  of  anhydrous  sulphuric  acid  is  passed  over 
the  salt,  carbonic  acid  gas  and  ordinary  sulphate  of  ammonia  are  ob- 
tained. In  sulphurous  acid  gas,  the  salt  remains  unaltered  at  ordinary 
temperatures;  on  the  application  of  heat,  a  yellow  sublimate  of  anhy- 
drous sulphite  of  ammon  is  first  obtained,  and  then  a  white  sublimate  of 
hydrated  sulphite  of  ammonia.  When  heated  in  hvdrosulphuric  acid  gas, 
it  is  only  partially  converted  into  bi-hydrosulphate  of  ammonia.  (H. 
Rose).' — The  salt  when  heated  alone,  evolves  carbonic  acid  gas,  the  decom- 
position beginning  at  a  temperature  of  49°;  afterwards  the  salt  b  is  evolved^ 
together  with  a  continually  increasing  quantity  of  sesquicarbonate  of  am- 
monia; and  lastly,  the  same  mixture  with  excess  of  water.  (J.  Davy.)  After 
the  salt  6,  the  salt  c  sublimes;  and  in  the  retort  there  remains  a  clear  liquid, 
which,  on  cooling,  deposits  crystals  of  sesquicarbonate  of  ammonia  with 
5  atoms  of  water,  while  mouocarbonate  of  ammonia  remains  dissolved  in 
the  mother  liquor.  (H.  Rose.) — The  salt  efiSioresces  in  the  air,  forming  a 
friable  mass  of  bicarbonate  of  ammonia,  while  anhydrous  carbonate  of 
ammon,  a,  sublimes;  this  takes  place  very  rapidly  if  the  salt  is  exposed 
in  the  state  of  powder.  (H.  Rose.)  According  to  Mitscherlich,  (Lehrb. 
2,  100,)  more  than  1  atom  of  ammonia  volatilizes  for  each  atom  of 
carbonic  acid ;  hence  a  solution  of  chloride  of  barium,  placed  with  the 
salt  under  an  air-tight  receiver,  becomes  ammon iacal  in  a  short  time. 
According  to  Dalton  {Ann.  Fhily  15,  137),  pure  ammonia  is  set  free. — If 
the  salt  is  treated  with  a  smaller  quantity  of  water  than  is  required  for 
perfect  solution,  the  water  dissolves  out  monocarbonate  of  ammonia, 
leaving  bi-carbonate  undissolved.  (Dalton;  Scanlan,  i^,  Bibl,  univ.  17, 
182; — J.  Davy; — H.  Rose.) — Accordingly,  if  small  quantities  of  water 


SESQUICARBONATE  OP  AMMONIA.  433 

ai'e  successively  added  to  the  salt,  and  poured  off  when  saturated,  the  first 
solution  shows  the  greatest  specific  gravity,  the  next,  a  lower  specific 
gravity,  and  so  on,  in  proportion  as  the  more  soluble  monocarbonate 
decreases,  and  the  less  soluble  bicarbonate  increases  in  quantity  in  the 
solution.  The  first  solution  evaporated  in  vacuo  leaves  efflorescent 
crystals  of  monocarbonate  of  ammonia;  the  latter  solutions  contain  bi- 
carbonate only;  the  portions  of  bicarbonate  which  remain  undissolved 
still  retain  the  form  of  the  salt  d,  originally  employed.  (Scaulan.) 

On  heating  the  complete  solution  obtained  by  using  a  larger  quan- 
tity of  water,  carbonic  acid  gas  is  disengaged,  with  traces  of  ammonia, 
till  monocarbonate  of  ammonia  alone  remains  in  the  liquid.  The  solu- 
tions of  the  other  salts  which  contain  more  than  1  atom  of  carbonic 
acid  to  1  atom  of  ammonia,  behave  in  a  similar  manner.  (H.  Rose.)-- > 
The  salt  when  boiled  with  alcohol  or  ether,  first  evolves  carbonic  acid, 
and  then  yields  a  sublimate  of  the  salt  6.  (Hiinefeld,  H.  Rose.) — At 
ordinary  temperatures,  alcohol  of  specific  gravity  0*829  removes  nearly 
pure  ammonia,  together  with  a  very  small  quantity  of  carbonic  acid,  and 
leaves  bicarbonate  of  ammonia.  More  dilute  alcohol  also  dissolves  out 
a  small  quantity  of  monocarbonate  of  ammonia  as  well  as  free  ammonia. 
(J.  Davy.) 

The  solution  of  this  salt  in  water  is  the  Spiritus  sails  ammoniaci 
aquosus.  In  the  old  method  of  preparing  it  by  distilling  a  mixture  of 
sal-ammoniac  with  carbonate  of  potash  and  water,  a  liquid  was  obtained, 
which,  if  an  excess  of  carbonate  of  potash  were  used,  contained  mono- 
carbonate and  also  caustic  ammonia,  because  the  carbonate  of  potash 
was  converted  into  bicarbonate. — ^When  a  sufficient  quantity  of  water 
is  employed  to  effect  complete  solution,  1  part  of  the  salt  at  18^,  dis- 
solves  in  4  parts  of  water,  at  16*7°  in  3*3  parts  at  32-2°;  in  2*7  parts 
at  40*6'^  in  2*4  parts;  and  at  49^  in  2  parts  of  water.  From  a  hot 
saturated  solution,  the  bicarbonate  of  ammonia  crystallizes  on  cooling. 
(J.  Davy.)  Alcohol  likewise  precipitates  crystallized  bicarbonate  from 
a  saturated  solution.  (Fischer,  Sckw.  53,  123.)  This  precipitate  was 
formerly  called  Ofa  llelmontii, 

0.  With  .5  0^07715  of  Water, — The  salt  d,  a,  is  gently  heated  in  a  retort 
to  the  neck  of  which  is  adapted  a  glass  tube  dipping  under  mercury,  till 
the  residue  fuses  to  a  clear  liquid.  From  the  latter,  after  some  weeks, 
the  salt  d,  0  crystallizes,  leaving  monocarbonate  of  ammonia  dissolved  in 
the  mother-liquor. 

Thin  six-sided  tables,  which  effloresce  in  the  air  and  are  converted 
into  bicarbonate  of  ammonia.  (H.  Rose.) 

Calculation.  H.  Rose. 

2NH3   ....  34  23-45  23*56 

3CO«    ....  66  45-52  4555 

5HO     ....  45  31-03  30*89 

d,  P 145  10000  100*00 

e.  Seven-fourths  Carbonate  q^  ilmmonta.— Produced  by  distilling  the 
bicarbonate  containing  3  atoms  of  water. 

Calcnlation.  H.  Rose. 

4NH3     68  20*60  19*41 

7C0« 154  46-67  47*70 

121IO  108  32-73  32*89 

e 330  10000  100*00 

Probably:  NH3,H0,C0«  +  3(NH',  HO,  2C0«)  +  8H0? 
VOL.   IT.  2    P 


434  NITROGEN. 

/.  Bicarbonate  of  Ammonia, — a.  With  2  atoms  of  Water. — 1.  Obtained 
in  one  instance  only  in  the  crystalline  form,  by  evaporating  in  yacno  a 
solution  of  the  monocarbonate  of  ammonia. — 2.  Deposited  in  the  form  of 
a  sparingly  soluble  powder,  when  a  perfectly  saturated  solution  of  the 
ordinary  sesquicarbonate  is  rapidly  evaporated  in  vacuo  over  oil  of 
vitriol;  the  powder  must  be  quickly  dried  between  folds  of  bibulous 
paper. — 3.  Remains  as  a  crystalline  mass,  when  an  aqueous  solution  of 
the  sesqui-carbonate  is  completely  and  slowly  evaporated  in  vacuo,  over 
potash,  lime,  or  chloride  of  calcium. — 4.  Or  when  the  +  ^-acid  salt  is  eva- 
porated over  oil  of  vitriol.  (H.  Rose.) — 5.  Remains  behind  when  the 
sesquicarbonate  is  kept  in  badly  closed  bottles.  (J.  Davy,  H.  Rose.) — 
6.  crystallizes  from  an  aqueous  solution  of  the  sesquicarbonate,  on  satura- 
ting it  with  carbonic  acid  gas.  (J.  Davy.) — 7.  Precipitated  from  a  solu- 
tion of  the  sesquicarbonate  by  alcohol.  (J.  Davy.) — 8.  Sometimes  formed 
in  the  preparation  of  carbonate  of  ammonia  on  the  large  scale.  (Phillips, 
Ann.  Fhil.  17,  110.) 

The  salt  obtained  by  the  first  method,  has  the  same  crystalline  form 
as  bicarbonate  of  potash,  to  which  it  corresponds  in  composition.  (H. 
Rose.) 


Phillips. 

J.  Davy. 

H.  Rose. 

Calculation. 

8 

1 

2                3 

5 

NH» 

....  17  ....  21-52 

...  21-16  . 

...  21-56  .. 

.  21-39  . 

..  21-24  ....  21-12  . 

..  21-60 

2CO« 

....  44  ....  55-69 

...  55-50  . 

...  5601  .. 

..  5609  . 

..  55-42  ....  55-95  . 

..  55-88 

2H0. 

18  ....  22-79 

...  23-34  . 

...  22-43  .. 

!.^ioo-bo~y. 

..  22-52  . 

..  23-34  ....  22-93  . 

...  22-52 

/,«. 

79  ....100-00 

....100-00  . 

..100-00  . 

.100-00  ...100-00  . 

.100-00 

The  numbers  8,  1,  2,  3,  5,  refer  to  the  different  methods  of  preparing 
the  salt. — Bicarbonate  of  ammonia  may  be  regarded  as  NH',  HO,  CO'  -4- 
HO,  C0».  (H.  Rose.) 

0.  With  2i  atoms  of  Water. — Sesquicarbonate  of  ammonia  is  digested 
in  a  strong  bottle,  with  a  sufficient  quantity  of  boiling  water  to  dissolve 
it,  and  the  bottle  immediately  closed  to  prevent  the  escape  of  carbonic 
acid:  When  the  solution  thus  obtained  is  allowed  to  cool  gradually,  it 
deposits  the  salt  in  crystals. 

Large,  transparent,  colourless  crystals,  with  smooth  brilliant  faces; 
belonging  to  the  right  prismatic  system  of  crystallization.  {Fig.  69)  u  :  u 
=  112°  9';  t  :  t  =  136*^  25';  y  :  y  backwards  =  118°  33';  p  :  t  =  158'' 
12-5';  p  :y=  149°  165';  i:t=  111°  47*5';  y  :  ot=  120°  435';  t  :u 
=  lOr  56^;  y\  u=  115°  5'.  Perfectly  cleavable  parallel  to  u.  (G.  Rose.) 
u  :  u  =  lir  48';  i:i=  135°  40';  y  :  y  =  117°  40'.  (Miller,  PhU.  Mag. 
Ann.  6,  40;  also  Fogg,  23,  558.) 

y.  WUh  3  atoms  of  ITo^r.—Sublimes  on  heating  the  salt  c,  j9.  (H. 
Rose.) 

Calculation.  H.  Rose.  Schrader.  BertlioUet.  Calculation.         H.Rose. 

2NH»....34  ....  20-36  ....  20-02  ....  19     ....       20  NH'  17  ....  19*32  ....  1812 

4C0*  ...88  ....  52-70  ....  62-89  ....  56     ....       65        2CO«  44  ....  5000  ....  50-67 
5HO  ....45  ....  26-94  ....  27-09  ....  25     ....       25        3HO    27  ....  30-68  ....  31-21 

/,/3     167  ....10000  ....100-00  ....100     ....     100  /,  7     88  ....10000  ...10000 

Schrader*s  and  BerthoUet's  salt  was  obtained  by  saturating  a  solution 
of  the  sesquicarbonate  with  carbonic  acid. 

The  salts/  «,  jS,  and  y  are  inodorous,  and  have  a  slight  but  not  alkaline 
taste,  though  they  turn  violet  juice  green.  They  volatilize  more  slowly 
than  the  monocarbonate,  and  without  becoming  opaque ;  according  to  J. 
Davy,  they  volatilize  the  more  quickly  in  proportion  to  the  quantity  of 
moisture  present  in  the  atmosphere,  because  the  water  sets  free  a  portion 


BORATE  OF  AMMONIA.  435 

of  the  carbonic  acid.  On  this  account^  the  vapour^  as  Schrader  foand,  has 
an  alkaline  reaction.  One  part  of  the  saAif,  a,  dissolves  at  12*8'^^  in  about 
6  parts  of  water ;  if  a  larger  quantity  of  salt  is  added  to  the  water,  it 
evolves  bubbles  of  carbonic  acid  gas,  even  at  this  temperature;  at  38*7** 
the  evolution  of  gas  is  rapid,  and  tbe  liquid  acquires  an  ammoniacal  odour. 
Hence  a  solution  of  the  sesquicarbonate  of  ammonia  cannot  be  saturated 
with  carbonic  acid,  at  ordinary  temperatures;  and  an  aqueous  solution  of 
the  bicarbonate,  whether  concentrated  or  dilute,  becomes  ammoniacal  by 
keeping. — Bicarbonate  of  ammonia  is  not  soluble  in  alcohol;  but  when 
exposed  to  the  air  under  alcohol,  it  dissolves  as  monocarbonato  with  dis- 
engagement of  carbonic  acid.  (J.  Davy,  vid,  also  Schrader,  A.  Oehl,  2, 
582;— BerthoUet,  N.  Gehl.  3,  555.) 

g.  Nine-fourtlis  Carbonate  of  Ammonia, — A  solution  of  sesquicarbonate 
of  ammonia  evaporated  in  vacuo  over  oil  of  vitriol,  so  slowly  as  not  to 
enter  into  ebullition,  deposits  small  crystals,  which  must  be  removed  before 
they  are  converted  by  efflorescence  into  the  salt  /,  a. — In  consequence  of 
the  oil  of  vitriol  absorbing  the  ammonia  from  the  volatilizing  carbonate, 
there  remains  an  atmosphere  of  carbonic  acid  gas,  which  gradually  com- 
bines with  the  salt  left  in  solution. — The  salt  readily  effloresces,  losing 
carbonic  acid  and  changing  into  the  salt/,  a. 

Calculation.  H.  Rose. 

4NH'     ....     68  ....  1910  ....  1912 

9CO» 198  ....  55-62  ....  55*83 

lOHO  90  ....  25-28  ....  25  05 

g 356  ....100-00  ....100*00 


Nitrogen  and  Boron. 
Borate  of  Ammonia. 

a.  Four-thirds  Borate. — 1.  The  salt  b  is  dissolved  in  a  isavered  vessel 
in  hot  and  very  strong  ammonia;  as  the  liquid  cools,  the  salt  a  crystallises 
out.— *2.  100  parts  of  crystallized  boracic  acid,  exposed  for  a  ooneiderable 
time  to  an  atmosphere  of  ammoniacal  gas,  absorb  21  parts  of  ammoBiA. 
(Arfvedson). 

Calculation.  Aifredson. 

3NH' 51*0  ....  20*88  ....  21*55 

4B03  139-2  ....  5700  ....  55*95 

6HO    540  ....  22*12  ....  22*50 

a 244-2  ....100*00  ....10000 

b.  Biborate. — Prepared  by  dissolving  a  moderately  large  qoaatity  of 
boracic  acid  in  hot  aqueous  ammonia,  and  slowly  cooling;  the  act  of 
solution  is  attended  wito  rise  of  temperature. — The  salt  crystallizes  in  semi^ 
transparent  rhombic  octohedrons,  not  so  acute  as  those  of  sulphur,  with 
truncated  terminal  summits,  and  frequently  also  with  truncated  edges. 
It  has  an  alkaline  taste  and  action.  (Gmelin.) 

Calculation.  Gmelin.      Arfiredson.     Soubeir^. 

NH»   ....  170  ....  12*92  ....     12*5     ....     12*88     ....     13544 

2BOa    ....  69-6  ....  52*89  ....     51  0     ....     63*34     ....     50*000 

5HO 45*0  ....  3419  ....     36-5     ....     23*78     ....     86'452 

b 131*6  ....100*00     ....  100  0     ....  100*00     ....     99*996 

Effloresces  in  the  air  and  is  converted,  with  loss  of  ammonia,  into  the 

2  F  2 


436  >^tTROGEN. 

quadroborate.     Soluble  in  aboat  12  parts  of  cold  water.     The  solution 
evolves  ammonia  when  heated. 

c.  Quadroboraie. — Prepared  by  saturating  a  hot  aqueous  solution  of 
ammonia  with  boraoio  acid^  and  slowly  cooling.  It  forms  colourless  and 
transparent,  irregular,  six-sided  prisms,  belonging  to  the  right  prismatic 
system,  with  four,  five,  or  six-sided  summits.  Appears  tasteless  at  firsts 
afterwards  excites  a  burning,  bitter  taste ;  has  an  alkaline  action  on  vege- 
table colours.  (Gmelin.)  Miller  (Pogg.  23,  558,)  describes  borate  of 
ammonia  as  crystallizing  in  square-based  octohedrons,  with  the  solid 
angles  of  the  base  perpendicularly  truncated,  and  an  inclination  of  the 
terminal  edges  =  105^  Id' j  he  does  not,  however,  state  which  of  the  three 
salts  he  examined. 


Calculation. 

Gmelin. 

Arfredson. 

Souberian. 

NH* 

....     170  .... 

7-76  .. 

5-9     . 

7-9     .... 

7-24 

4BO» 

....  139-2  .... 

63*50  .. 

..     63-4     . 

...     640    .... 

55-80 

7HO... 

....     63-0  .... 

28-74  .. 

..     30-7     . 

..     28-1     .... 

36-96 

e 219-2  ....100-00  ....  lOO'O     ....  1000     ....  10000 

Permanent  in  the  air;  when  heated  it  swells  up  and  fnses,  leaving 
vitrefied  boracic  acid. — It  dissolves  in  about  8  parts  of  cold  water;  this 
solution  also  gives  ofi*  ammonia  when  boiled.  (  Vid.  Lasonne,  Cr€ll.Ckem,J. 
5,  83; — Wenzel,  Le^ire  von  der  Verwandtschaft,  355; — L.  Gmelin,  Sckw, 
15,  258; — Soubeiran,  J.  Pharm.  1134; — Arfvedson,  Pogg,  2,  130.) 


Nitrogen  and  Phosphorus. 

A,    Phosphide  op  Nitrogen.    N*P. 

Formed  in  the  decomposition  of  ammonio-terchloride  of  phosphorus  or 
ammonio-terbromide  of  phosphorus  by  heat. 

Preparation. — 1.  Terchloride  of  phosphorus  freed  by  repeated  diatil- 
lation  from  all  excess  of  phosphorus,  and  surrounded  by  a  freezing 
mixture,  is  slowly  saturated  with  ammoniacal  gas.  The  compound  is 
then  rapidly  introduced — ^before  it  can  absorb  moisture  from  the  air — 
into  a  wide  tube  of  difficultly  fusible  glass,  and  the  atmospheric  air 
expelled  by  a  current  of  dry  carbonic  acid  gas.  It  is  then  heated  in  a 
strong  charcoal  fire  for  a  considerable  time,  till  no  more  traces  of  sal-ammo- 
niac vapour  are  evolved,  the  current  of  carbonic  acid  gas  being  kept  up 
throughout  the  process,  and  not  arrested  till  the  whole  has  become  per- 
fectly cold.  (H.  Rose.) — 2.  Vapour  of  terchloride  of  phosphorus  is  passed 
over  sal-ammoniac,  which  is  heated  till  it  volatilizes.  Hydrochloric  acid 
and  phosphorus  escape,  phosphide  of  nitrogen  remains  in  bulky  masses 
spotted  with  white,  red,  and  orown. 

2PC1»  +  2(NH»,  HCl)  =  N«P  +  8HC1  +  P. 

If  pentachloride  of  phosphorus  is  used,  a  white  phosphide  of  nitrogen 
is  obtained,  which  however  even  after  prolonged  ignition  in  a  current  of 
carbonic  acid  gas,  still  retains  between  1  -5  and  3  per  cent,  of  chlorine, 
besides  hydrogen,  and  conseauently  evolves  a  small  quantity  of  ammonia 
when  ignited  with  copper.  (W5hler  &  Liebig.) 

White  bulky  powder,  which  neither  fuses  nor  volatilizes  when 
exposed  to  a  moderately  strong  red  heat  out  of  contact  of  air.  If 
the   ammonio-chloride  of  phosphorus    contains    moisture   previous    to 


PHOSPHIDE  OF  NITROGEN.  437 

ignition^  the  resulting  phosphide  of  nitrogen  exhibits  a  reddish  colour, 
(H.  Rose.) 

Calculation.  H.  Rose.         Wohler  &  Liebig. 

2N    28-0  4714  47*32  49 

P     31-4  52-86  52-68  51 

N«P 59-4  10000  100-00  100 

Decompontions, — 1.  Phosphide  of  nitrogen  when  heated  in  the  air, 
evolves  white  fumes  of  phosphoric  acid,  and  is  slowly  oxidized,  without 
Hame,  producing  phosphoric  acid.  (H.  Rose.) — 2.  It  is  scarcely  acted  on 
bv  dilute  nitric  acid;  strong  nitric  acid  converts  it  very  slowly  into  phos- 
phoric acid.  It  dissolves  in  oil  of  vitriol,  with  disengagement  of  sulphur- 
ous acid;  the  solution  contains  phosphoric  acid.  (H.  Rose.) — 3.  Ex- 
plodes violently  when  heated  with  a  nitrate.  (H.  Rose.)  Also  with 
chlorate  of  potash,  chlorine  gas  being  disengaged.  (Wohler  Sc  Liebig.) 
When  fused  with  hydrate  of  potash  it  is  readily  decomposed,  the  decom- 
position being  frequently  attended  with  incandescence ;  when  fused  with 
hydrate  of  baryta,  powerful  incandescence  invariably  ensues ;  the  results 
in  both  cases  are  nitrogen  gas  and  hydrogen  gas  in  about  equal 
volumes,  together  with  ammonia  and  phosphate  of  the  fixed  alkali. 
According  to  H.  Rose,  2N'P  yields  with  lOHO  from  the  alkaline  hydrate, 
2PO«  +  3NH'  +  H  +  N;  but  why  the  whole  of  the  hydrogen  is  not  em- 
ployed  in  the  formation  of  ammonia,  according  to  the  formula,  SN'P  + 
15H0  =  3P0*  +  5NH'  +  N,  remains  yet  to  be  explained.  An  alka- 
line phosphate  is  also  produced,  with  rapid  disengagement  of  carbonic 
acid  gas,  when  phosphide  of  nitrogen  is  ignited  with  carbonate  of 
potash  or  soda.  (H.  Rose.) — 4.  When  a  mixture  of  phosphide  of  nitrogen 
and  red  oxide  of  mercury  is  heated,  it  fuses  and  is  decomposed,  with 
disengagement  of  light  and  heat---evolving  vapour  of  mercury  and 
leaving  phosphate  of  mercury,  which,  on  being  further  heated,  leaves 
a  residue  of  phosphoric  acid.  Again,  when  phosphide  of  nitrogen  is 
heated  with  oxide  of  copper,  flame  and  sparks  are  emitted  and  hypo- 
nitric  acid  formed.  (Wohler  &  Liebig.) — 5.  Dry  sulphuretted  hydrogen 
gas  passed  over  ignited  phosphide  of  nitrogen,  volatilizes  it  completely 
in  white  clouds,  which  condense  to  a  white  or  yellowish-white  powder. 
This  powder  takes  fire  in  the  air  at  a  summer-heat,  and  bums  with 
a  vivid  white  flame,  leaving  phosphoric  acid.  By  nitric  acid  it  is 
violently  oxidized  and  dissolved,  leaving  only  a  small  quantity  of  sul- 
phur; the  solution  contains  sulphuric  acid  and  phosphoric  acid.  It 
also  iuflames  in  the  vapour  of  hyponitric  acid.  When  recently  prepared, 
it  is  inodorous ;  but  when  exposed  to  the  air  for  some  time,  it  acquires 
the  odour  of  hydrosulpharic  acid.  With  water,  it  forms  a  milky  solution 
which  smells  of  hydrosulphuric  acid,  and  deposits  sulphur  when  kept  out 
of  contact  of  air;  the  supernatant  liquid  reddens  litmus,  and  gives  with 
chloride  of  barium,  on  the  addition  of  ammonia,  a  copious  precipitate  of 
phosphate  of  baryta.  With  hydrate  of  potash  it  evolves  ammonia ;  it 
dissolves  completely  in  hot  solution  of  potash,  but  not  in  solution  of  am- 
monia or  in  hydrochloric  acid,  which  it  renders  milky.  (H.  Rose.)  [Can 
this  powder  be  2NH^  PS«  produced  from  N'P-|-6HS?]— 6.  Dry  hydro- 
gen gas  transmitted  over  ignited  phosphide  of  nitrogen,  converts  it 
into  ammonia  and  phosphorus,  which  is  deposited  in  yellow  or  brownish 
drops.  Phosphide  of  nitrogen  is  not  decomposed  at  a  red  heat  by  anhy- 
drous chlorine,  hydrochloric  acid,  carbonic  acid,  or  ammouiacal  gas ;  when 
moisture  is  present,  hydrochloric  acid  gas  gives  rise  to  the  formation  of  a 


438  NITROGEN. 

dtnall  quantity  of  ammonia.  It  is  not  decomposed  when  fused  and  dis- 
tilled with  sulphur.  It  is  not  altered  in  composition  or  dissolved,  bj 
dilute  hydrochloric,  sulphuric,  or  nitric  acid,  or  even  by  boiling  alkaline 
solutions.  (H.  Rose.) 

B.     Phosphaiiide. 

Hydrate  of  Phosphide  of  Nitrogen, — Formed  by  saturating  pentachlo- 
ride  of  phosphorus  with  ammoniacal  gas ;  extracting  the  greater  part  of 
the  sal-ammoniao  by  washing  with  water;  then  removing  the  last  portions 
of  that  substance,  which  adhere  obstinately,  by  boiling  first  with  caustic 
potash,  and  afterwards  with  nitric  (or  sulphuric  acid),  and  finally  washing 
with  water. 

White  powder,-^volves  ammonia  when  heated  alone  j  when  ignited 
with  oxide  of  copper,  it  yields  ammonia,  white  phosphide  of  copper,  and 
a  red  fusible  substance,  which  probably  consists  of  phosphate  of  dinoxide 
of  copper.  (Wdhler  &  Liebig.) 

IT  When  heated  alone,  without  access  of  air,  it  evolves  ammonia,  and 
leaves  a  new  compound  called  Biphosphamide  (p.  439).  If  it  be  moist 
when  heated,  it  is  resolved — completely,  according  to  Gerhardt,  incom- 
pletely, according  to  Gladstone — into  ammonia  and  metaphosphorio  acid* 
If  the  air  has  access  to  the  substance  while  heat  is  applied  to  it,  and  the 
temjperature  is  slowly  raised  to  between  200°  and  300°  ammonia  is 
evolved — the  substance  increases  in  weight  (from  oxidation) — and  is  con- 
reried  into  a  dark-coloured  mass,  which  is  resolved  by  water  into  an 
insoluble  portion  consisting  of  biphosphamide,  and  an  insoluble  portion 
eonsisting  mainly  of  phosphate  of  ammonia.  Insoluble  in  water;  but 
when  boiled  with  that  liquid  it  is  very  slowly  decomposed,  phosphoric 
acid  and  ammonia  remaining  in  solution.  The  decomposition  is  accele- 
rated by  the  presence  of  caustic  potash,  the  ammonia  being  then  evolved 
as  gas.  Sulpnuric  acid  has  no  effect  upon  it  in  the  cold,  but  decomposes 
it  when  heated,  the  solid  matter  entirely  disappearing,  and  phosphoric 
acid  and  ammonia  remaining  in  the  solution :  no  sulphurous  acid  is 
evolved,  but  the  liquid  acquires  a  dark  colour.  To  proauce  this  effect, 
the  sulphuric  acid  must  be  but  very  little  diluted.  When  the  substance 
i^  fusea  with  caustic  potash,  ammonia  is  evolved  and  phosphate  of  potash 
remains.  It  resists  the  action  of  most  oxidizing  agents ;  is  not  affected 
by  boiling  in  nitric  acid,  or  a  mixture  of  nitric  and  sulphuric  acids; 
slowly  oxidized  by  fusion  with  nitre ;  deflagrates  when  heated  with  chlo- 
rate of  potash.  Chlorine  has  no  effect  upon  it,  either  in  the  cold  or  at  any 
temperature  short  of  that  at  which  the  substance  itself  is  decomposed. 
Insoluble  in  alcohol  or  oil  of  turpentine.  (Gladstone.) 

According  to  Gerhardt. 
According  to  Wohler  &  Liebig.  Calculation.  Exp. 

Calculation.  Exp.         P   32  40*5  40'35 

2N  28    3618  3305         H' 3  38  3*90 

P  31-4 40-57  40-68         N» 28  35*4  35*00 

2H0  18    23-25  24-27        0« 16  203  20-76 

N«P.  2HO  77-4 100-00  100-00    PH^N*0«....  79  100-0  100*00 

According  to  Gladstone. 
CalcalBtion.  Exp. 

a.  b.  e. 

P     32  3107  3204  31*83  30*41 

H»  3  2-91  3*35  3-56 

N*  28  27-19  27-29  27*69 

0»  40  38-33  37-32  36-92 

PH»N*0»  103  100*00  100*00  100*00 


PHOSPHAMID£.  439 

Oladstone's  results  accord  more  nearly  with  the  formula  P*H*N*0', 
Whicb    gives    3232  P4-303  H  + 28-28  N +  36-36  0;   but    the    formula 
PH'N*0*  is  rendered  more  probable  by  the  mode  of  formation  of  the  sub- 
stance, inwhich  it  must  be  observed  that  oxidation  plays  an  essential  part : 
PCI*  +  7NH=»  +  2HO  +  30  =  5rNH^  CI)  +  PH«N*0«. 

Gerhard t,  on  the  other  hand,  maintains  that  chlorophosphamide,  the  sub- 
stance formed  by  the  action  of  ammonia  on  pentachloride  of  phosphorus, 
is  composed  of  PCPN^H*,  being  formed  in  the  manner  represented  by 
the  equation  : 

PCF  +  2NH'  =  PCPN«H*  +  2HCI5 

and  that  when  this  substance  comes  in  contact  with  water,  hydrochloric 
acid  and  phosphamide  are  produced: 

PCl»N*H*  +  2HO  =  3Ha  +  PH»N«0«. 

This  compound  has  not  yet  received  an  appropriate  name;  the  term 
Hydraie  of  phosphide  of  nitrogen^  originally  applied  to  it  by  W5hler  k 
Liebig,  is  manifestly  incorrect;  and  Qerhardt*s  name,  Phosphamide^  is 
liable  to  the  objection  that  the  nitrogen  and  hydrogen  contained  in  the 
substance  are  not  in  the  proportion  to  form  amidogen. 


%   C.      BiPHOSPHAMIDB. 

Formed  by  the  action  of  heat  on  dry  phosphamide  (p.  438),  all  the 
hydrogen  and  half  the  nitrogen  in  that  substance  being  evolved  in  the 
form  of  ammonia,  and  the  new  substance,  biphosphamide,  remaining 
behind  : 

PH^N^O*      =     NH»  +  PNO«    (Gerhardt) 
or:      PH3N«0»  NH'  +  PNO«    (Gladstone.) 

The  phosphamide  should  be  heated  in  a  narrow  tube  open  at  one  end, 
or  better,  in  a  gas  containing  no  oxygen;  because,  if  air  has  access  to  the 
heated  substance,  the  action  which  takes  place  is  altogether  different. 
(Gladstone.) 

Properties, — Grey  powder,  insoluble  in  all  the  ordinary  menstrua,  and 
showing  no  tendency  to  combine  either  with  acids  or  with  alkalis.  Fuses 
at  a  full  red  heat,  and  on  cooling,  solidifies  to  a  black  vitreous  mass :  no 
combustion  takes  place ;  the  weight  remains  unaltered.  (Gladstone.) 

According  to  Gladstone. 

Calculation.  Exp. 

32  37-21  38-82 

14  16-28  16-33 

40  46-51  44-85 


According  to  Gerhardt. 

Calculation. 

Exp. 

p... 

32  51-6  

50-6 

P 

N... 

14  22-6  

22-4 

N 

20« 

16  25-8  

27-0 

50 

PNO« 62  100-0  1000     PNO» 86  100*00  lOO'OO 

Decompositions. — When  biphosphamide  is  moistened  with  water  and 
heated,  it  is  converted,  but  not  completely,  into  phosphoric  acid  and  ammo- 
nia. It  is  not  affected  by  boiling  with  solution  of  potash ;  but  when  fused 
with  solid  hydrate  of  potash,  it  evolves  ammonia  and  leaves  phosphate  of 
potash.  Resists  the  oxidizing  action  of  nitric  acid,  but  deflagrates  when 
fused  with  nitre.  Unaffected  by  chlorine,  both  at  ordinary  temperatures, 
and  when  heated;  iodine  or  sulphur  heated  with  it,  sublimes  without 


440  NITROGEN. 

producing  any  change.  Heated  in  a  stream  of  hydrosulphuric  acid  gaa 
prepared  from  sulphide  of  antimony,  it  assumes  a  dark,  semi-fused,  sticky 
appearance,  and  increases  somewhat  in  weight.  When  it  is  heated  in  a 
current  of  hydrogen,  ammonia  is  given  off,  and  white  fumes,  consisting  of 
phosphoric  or  phosphorous  acid  mixed  with  spontaneously  inflammable 
phosphuretted  hydrogen,  pass  along  the  tube ;  at  the  same  time,  a  red 
substance — probably  impure  phosphoric  oxide — sublimes  in  the  tube,  and 
water  condenses.  There  is  always  a  portion  of  the  substance  left  which 
resists  the  action  of  the  hydrogen. 


According  to  Gerhardt,  the  residue  obtained  by  heating  chloro-phos- 
phide  of  nitrogen  does  not  consist  of  phosphide  of  nitrogen,  as  stated  on 
page  436,  but  contains  hydrogen,  and  is  a  mixture  of  blphosphamide  with 
a  compound  of  phosphorus,  hydrogen,  and  nitrogen,  whose  composition  is 
expressed  by  the  formula  PIl  N^ ;  this  substance  Gerhardt  calls  Phospham. 
According  to  Gladstone,  however,  this  cannot  be  the  case ;  for  the  sub* 
stance  in  question  (phosphide  of  nitrogen)  is  decomposed  and  rendered 
wholly  volatile  by  hydrosulphuric  acid;  but  biphosphamide  is  unaffected 
by  that  re-agent,  and  cannot  therefore  be  present  in  the  substance  in 
question.  Moreover,  Gerhardt*s  own  experiments  give  only  0*7  per  cent,  of 
hydrogen  in  (he  so-called  ji7Ao«^^m,  whereas  the  ^rmula  PHN*  requires 
1*64  per  cent. :  hence  it  would  be  necessary  to  suppose  the  phospham  to 
be  contaminated  with  about  its  own  weight  of  biphosphamide.  {Compare 
Liebig  &  WoYAet,  Ann,  Phamt.  11,  139;  Gerhardt,  N,  Ann.  Chim,  Phys, 
18,  188;  Gladstone,  <?«.  J,  ofChem,  Soc,  2,  121.)  IT 


D.  Compound  op  Phospuoric  Oxide  and  Ammonia. 

1000  parts  of  phosphoric  oxide  rapidly  absorb  between  48  and  49  parts 
of  ammoniacal  gas,  but  no  more.  The  resulting  compound  is  NH^  5P'0. 
It  is  black,  and  loses  part  of  its  ammonia  in  a  dry  atmosphere,  but  retains 
the  remaining  portion  so  tenaciously  that  weak  acids  cannot  separate  it ; 
sulphuric  or  hydrochloric  acid,  however,  remove  it  rapidly  with  the  aid  of 
heat,  or  in  24  hours  at  ordinary  temperatures,  at  the  same  time  restoring 
the  red  colour  of  the  phosphoric  oxide.  In  an  aqueous  solution  of  am- 
monia, phosphoric  oxide  also  turns  black,  but  is  rapidly  converted  into 
phosphuretted  hydrogen  gas  and  phosphate  of  ammonia.  (Leverrier,  Ann. 
Chim.  Phys,  65,  266.) 

With  this  compound  also  the  following  substance — discovered  by 
Pelletier,  and  more  accurately  examined  by  Bockmann  ( Vers,  iiber  das 
VerhaUen  des  Phospltors  in  verschiedeneii  Gasarten ;  Erlangen,  1 800, 
«.  297),  and  by  A.  Vogel  (Gilb.  45,  66;  48,  376),  and  considered  to  be 
phosphide  of  ammonia — appears  to  be  identical.  Phosphorus  absorbs 
ammoniacal  gas,  especially  under  the  influence  of  light,  and  is  converted 
into  a  brownish-black  powder,  which,  however,  turns  yellow  after  some 
days,  unless  moistened  with  solution  of  ammonia.  The  compound  enters 
into  slow  combustion  at  a  temperature  just  above  25°,  but  does  not  take 
fire  till  heated  to  90°.  In  chlorine  gas,  it  burns  at  ordinary  temperatures 
with  a  much  more  brilliant  yellowish- white  flame  than  phosphorus  itself. 
When  heated,  it  turns  red,  but  does  not  fuse  below  a  rea-heat,  when 
ammonia  and  phosphuretted  hydrogen   gas  are  evolved.     Hydrate  of 


PHOSPHATE  OF  AMMONIA.  441 

potash  disengages  ammoniacal  gas  from  it,  and  forms  a  soft  brown  sub- 
stance,  from  which  hydrochloric  acid  expels  phospharetted  h^rdrogen  gas. 
Hydrochloric  acid  separates  but  a  small  quantity  of  ammonia  from  the 
phosphide  of  ammonia,  even  at  a  boiling  heat.  (A.  Vogel.) — Bineau 
\Ann,  Chim,  Phys,  67,  229)  did  not  succeed  in  the  attempt  to  form  this 
compound ;  the  phosphorus  sublimed  in  the  ammoniacal  gas  when  exposed 
to  the  sun's  rays,  and  became  somewhat  darker,  but  did  not  absorb 
ammonia.  [Prooably  the  presence  of  a  trace  of  water  is  necessary,  iu 
order  that  jphosphoric  oxide  may  be  formed  under  the  influence  of  the 
solar  light.  J 

E.     Hypophosphite  of  Ammonia. 

Deliquescent  in  the  air,  very  soluble  both  in  water  and  absolute 
alcohol.  (Dulong.)  Very  much  like  the  potash  salt;  when  heated,  it 
first  evolves  ammonia,  and  then  leaves  hydrated  hypophosphorous 
acid,  which  is  also  decomposed  on  further  exposure  to  heat.  (H.  Rose, 
Fogg.  12,  85.) 

F.    Phosphite  of  Ammonia. 

An  aqueous  solution  of  phosphorous  acid  saturated  with  ammonia  and 
evaporated  to  a  syrupy  consistence,  yields  large  four-sided  prisms  with 
quadrilateral  summits.  When  heated,  the  salt  loses  its  ammonia,  and 
leaves  hydrated  phosphorous  acid,  which  at  a  higher  temperature  is 
resolved  in  the  usual  manner  into  phosphuretted  hydrogen  gas  and 
phosphoric  acid.  The  salt  deliquesces  rapidly  in  the  air.  (Fourcroy  ^ 
Vauquelin — H.  Rose,  Fogg,  9,  28.) 


G.    Ordinary  Phosphate  of  Ammonia. 

a.  Triphosphate  ?  A  concentrated  solution  of  salt  b,  mixed  with  am^ 
monia,  solidifies  to  a  magma,  in  consequence  of  the  separation  of  salt  a; 
in  the  air,  however,  the  mixture  gives  off  ammonia  and  is  reconverted 
into  salt  6.  (Berzelius.) 

6.  Dipkotp/uUe. — Formerly  called  Neutral FhosphaU, — ^Occurs  generally 
in  combination  with  phosphate  of  soda  and  phosphate  of  magnesia,  in  the 
urine  of  carnivorous  animals.  To  prepare  it,  carbonate  of  ammonia  is 
added  to  aqueous  phosphoric  acid  contaming  lime,  till  a  further  addition 
ceases  to  cause  effervescence  and  precipitation  of  phosphate  of  lime ;  the 
solution  is  then  filtered  and  evaporated,  and  the  ammonia  which  volati- 
lizes during  the  evaporation  replaced,  so  that  the  liquid  may  have  rather 
an  alkaline  than  an  acid  reaction  j  it  is  then  left  in  a  cool  place  to  crys- 
tallize. It  forms  large,  colourless,  transparent  crystals,  which  belong  to 
the  oblique  prismatic  system.  {Fig,  91,  43,  94,  95  &  96.)  *  :  axis  =  113** 
34';  i\u=i  105°  22';  i  :/=  109°  44';  u  :  u'  =  84^30';  %  :  »  =  123'' 
20-5';/  :  axis  =  137°  2';  /  :  w  =  119°  28'.  (Mitscherlich.)  t  :  m  =  105° 
50';  i  :/=  109°  32';  u  :  u'  =  84°  15'.  (Brooke,  Ann.  PhU.  22,  285.) 
It  has  a  cooling,  saline,  pungent  taste,  and  alkaline  reaction. 

Calculation.  Mitecherlich. 

2NH3      .340  25-68 

cPO»       „ 71-4  5.3-93  54-426 

3H0       270  20-39 

2NH*0,HO,cPO»    ....  132-4  10000 


442  NITROGEN. 

The  salt  effloresces  superficially  in  the  air^  and  loses  a  portion  of  its 
ammonia;  even  at  ordinarjr  temperatures.  When  heated,  it  first  under- 
goes the  aqueous  fusion — then  dries  up— «.nd  at  a  red-heat  is  couTerted, 
with  slow  and  imperfect  expulsion  of  ammonia,  into  hydrated  phosphoric 
acid  in  a  state  of  igneous  fusion;  according  to  Proust,  the  hydrated  acid 
amounts  to  0*62  of  the  salt.  The  salt  dissolves  in  4  parts  of  cold,  and  in 
a  smaller  quantity  of  hot  water ;  the  solution  loses  a  portion  of  ammonia 
bj  the  mere  application  of  heat.     The  salt  is  insoluble  in  alcohol. 

c.  Monophosphate, — Formerly  called  the  Acid  Phosphate. — An  aqueous 
solution  of  ammonia  is  treated  with  phosphoric  acid,  till  the  solution 
reddens  litmus  strongly  and  no  longer  precipitates  chloride  of  barium. 
The  salt  belongs  to  the  square  prismatic  system  of  crystallizatiou.  {Fiff. 
23  and  30.)  e  :  ef  =z  119"  46';  e  :  c*  =  90*»  25'j  «  :  r  =  135«  12-5'. 
Not  quite  so  soluble  in  water  as  6.  (Mitscherlich,  Ann,  Chim.  Phys,  19 , 
373.) 

Calculation.  Mitacherlich. 

NH>      170  14-73 

cPO*      71-4  61-87  6102 

3HO       27-0  23-40 

NH*0,2H0,cP0«  ....  115-4  10000 

Pybophosphatb  of  Ammonia. 

Known  only  in  the  state  of  solution;  as  soon  as  the  solution  is  evapo- 
rated, the  acid  takes  up  1  atom  of  basic  water,  and  yields  crystals  of 
%  b.  (Graham^  Ann.  Pharm,  29,  19.) 

Metaphosphatb  of  Ammonia. 

Likewise  known  only  in  the  state  of  solution.  When  the  solution  is 
allowed  to  evaporate  spontaneously,  the  salt  is  conyertedj  on  crystalliiing, 
into  E,  C.  (Graham.) 

Nitrogen  and  Sulphur. 

A.    Sulphide  of  Nitrogen. 

Prepatatum,  The  compound  of  protochloride  of  sulphur  with  2  atoms 
of  ammonia  is  prepared  according  to  the  second  method,  p.  482;  (the 
compound  obtained  by  the  first  method  deposits  free  sulphur  in  addition 
to  sulphide  of  nitrogen,  on  the  addition  of  water);  it  is  then  decomposed 
with  cold  water,  which  principally  dissolves  sal-ammoniac  and  hyposul- 
phite of  ammonia,  and  separates  sulphide  of  nitrogen.  The  latter  is 
rapidly  washed  with  cold  water,  till  the  liquid  runs  off  colourless  and  free 
from  chlorine.  It  is  then  washed  twice  with  absolute  alcohol  to  remove 
the  water,  pressed  between  folds  of  bibulous  paper,  and  quickly  dried  in 
vacuo  over  oil  of  vitriol.  Should  it  contain  free  sulphur,  the  latter  must 
be  removed  by  repeated  boiling  in  ether.  When  sulphide  of  nitrogen  is 
free  from  sulphur,  it  dissolves  in  hot  water  without  leaving  a  residue. 
(Soubeiran.) 

Properties,  Light  green  powder.  When  heated  to  100**,  it  becomes 
permanently  yellow  without  alteration  of  weight;  at  ordinary  temperatures 


SULPHIDE  OF  NITROGEN-  44S 

thd  samd  change  takes  place  on  exposure  to  ammoniacal  gas  or  to  the  vapour 
of  protochloride  of  sulphur.  The  sulphide  of  nitrogen  prepared  from  the 
ammonio-chloride  of  sulphur,  made  according  to  the  first  method,  is  yellow 
from  the  commencement.  Hence  there  are  two  isomeric  states  of  this 
compound.  It  crystallizes  from  a  solution  in  hot  ether.  When  rubhed, 
it  becomes  highly  electrical  and  tenacious;  but  if  it  has  been  tarned  yel- 
low in  an  atmosphere  of  ammoniacal  gas,  it  no  longer  exhibits  tnese 
changes.  It  is  inodorous  except  when  heated,  tasteless  at  first,  but 
afterwards  exhibits  a  transient  pungent  taste.  When  applied  to  tender 
parts  of  the  skin,  it  produces  itching.  (Soubeiran.) 

Calculation  according  to  Soubeiran. 

N  14     22-58 

3S 48     77-42 

NS»  62     100-00 

Decompositions  — 1.  Resolved  by  heat  into  nitrogen  gas  and  sulphur. 
A  small  quantity  of  undecoroposed  sulphide  of  nitrogen  mixes  with  the 
nitrogen  in  the  state  of  vapour,  and  may  he  recognized  by  its  aromatic 
odour;  it  also  forms  a  crystalline  sublimate.  The  disengagement  of  ni- 
trogen commences  at  140°  and  slowly  continues  at  this  temperature;  but 
when  the  compound  is  strongly  heated,  the  evolution  of  nitrogen  is  at- 
tended with  deflagration  and  explosion. — 2.  In  cold  water,  sulphide  of 
nitrogen  disappears  in  a  few  days,  but  rapidly  in  hot  water — being  dis- 
solved in  the  form  of  hyposulphite  of  ammonia  with  excess  of  acid. — 
(NS^  +  3H0  =  NH'  +  3S0.)  If  the  water  contains  an  alkali  in 
solution,  the  decomposition  takes  place  more  rapidly;  in  concentrated 
ammonia,  the  decomposition  is  attended  with  so  much  disengagement 
of  heat,  that  ammoniacal  gas  free  from  nitrogen  escapes  with  effer- 
vescence. In  acidulated  water,  the  decomposition  takes  place  as  in 
pure  water,  except  that  in  the  former  case,  sulphur  is  separated  from 
the  hyposulphurous  acid. — 3.  Sulphide  of  nitrogen  dissolves  in  absolute 
alcohol  containinff  sulphide  of  sodium  or  soda  in  solution,  and  forms  a 
dark  hyacinth-rea  liquid;  but  the  solution  undergoes  decomposition  in  a 
few  seconds.  (Soubeiran.) 

Combinations,  a.  Sulphide  of  nitrogen  dissolves  in  protochloride 
of  sulphur,  producing  a  dark  reddish  brown  solution.  If  the  solution 
is  introduced  into  a  tubulated  retort  surrounded  with  hot  water,  and  car- 
bonic acid  gas  passed  through  the  tubulure,  chloride  of  sulphur  volatilizes, 
together  with  a  small  quantity  of  sulphide  of  nitrogen;  yellow  crystals  of 
chloro-sulphide  of  nitrogen  are  sublimed  (recognizable  by  the  blue  colour 
produced  by  ammonia);  and  in  the  retort  there  remains  a  red  substance, 
which  appears  to  contain  an  excess  of  chloride  of  sulphur. 

b.  Sulphide  of  nitrogen  is  very  sparingly  soluble  in  alcohol,  but 
dissolves  more  readily  in  ether,  from  which  it  crystallizes  on  evaporation. 

Stdphide  of  Nitrogen  with  a  larger  proportion  of  Sulphur  ?  Gregory's 
Sulphide  of  Niti^ogen, — Chloride  of  sulphur  is  slowly  dropped  into  an 
aqueous  solution  of  ammonia,  in  such  quantity  that  the  ammonia  may  re- 
main in  excess,  and  the  mixture  left  to  itself  till  the  red  compound  first 
precipitated  has  become  yellow.  (Gregory,  Soubeiran.)  The  precipitate  ob- 
tained from  chloride  of  sulphur  saturated  with  sulphur,  yields  the  maximum 
quantity  of  sulphide  of  nitrogen;  the  precipitate  obtained  with  proto- 
chloride of  sulphur,  yields  scarcely  a  trace.  (Gregory.)     In  this  manner. 


444  NITROGEN. 

a  pale  yellow,  brittle  mass  is  obtained  which  becomes  red  and  soft  at  tern* 
peratures  even  below  100°.  According  to  Gregor)r,  it  is  to  be  regarded 
as  a  compound  of  his  crystallized  sulphide  of  nitrogen  with  excess  of 
sulphur.  According  to  Soubeiran,  it  oYolves,  when  heated,  a  small 
quantity  of  nitrogen  and  ammoniacal  gases  in  equal  volumes,  and  leaves 
sulphur;  with  alcohol  containing  potash  it  yields  an  amethyst-red  coloured 
solution,  which  rapidly  becomes  colourless  in  conseauence  of  the  forma* 
tion  of  hyposulphite  of  potash.  It  gives  up  hyposulphite  of  ammonia  to 
boiling  water,  the  residue  still  possessing  the  property  of  reddening  alcohol 
which  holds  potash  in  solution. 

When  the  pale  yellow  substance  is  repeatedly  boiled  with  large 
quantities  of  alcohol,  it  dissolves  completely.  The  solution  thus  obtain^, 
deposits  crystals  of  sulphur  on  cooling,  and  by  further  evaporation  and 
cooling  more  crystals  are  formed.  The  remaining  mother-liquor  yields 
Gregory's  crystallized  sulphide  of  nitrogen  j  the  mother-liquor  sometimes 
also  contains  a  liquid  lighter  than  water,  of  ethereal,  pungent  odour,  and 
soluble  in  water  and  alcohol;  it  appears  likewise  to  redden  alcohol  con- 
taining potash.  (Gregory.) 

Crystallized  sulphide  of  nitrogen  is  colourless.  When  dried  as  com- 
pletely as  possible  without  tbe  aid  of  heat,  it  is  found  to  contain  between 
92  and  93  per  cent,  of  sulphur  and  between  5'5  and  6*5  per  cent,  of  ni- 
trogen with  a  trace  of  hydrogen;  heuce  its  formula  will  be  about  NS'*. 
(Gregory.)  When  heated,  it  gives  off  rather  more  nitrogen  and  ammo- 
niacal gas  than  the  pale  yellow  substance.  (Soubeiran.)  With  potash 
or  lime  it  evolves  ammonia  only  when  heated,  and  forms  sulphide  of 
potassium  or  calcium.  Its  alcoholic  solution  assumes  a  splendid  purple 
red  colour  on  the  addition  of  potash,  ammonia,  or  baiyta;  a  quantity 
amounting  to  no  more  than  the  y^^^  part  is  sufficient  for  this  purpose;  the 
liquid,  however,  soon  becomes  colourless  and  deposits  colourless  crystals 
of  hyposulphite  of  potash.  An  aqueous  solusion  of  potash  does  not  form 
a  red  coloured  solution  with  sulphide  of  nitrogen.  Sulphide  of  nitrogen 
is  insoluble  in  water,  but  dissolves  readily  in  alcohol.  The  solution  at 
first  tastes  like  wild  fruit,  then  pungent,  and  lastly  hepatic.  (Gregory.) 


B.    a.  Sulphite  op  Niteic  Oxide.     NO',  SO*. 

Nitrosidphuric  acid,  Acide  nUrosuJpkurique,  StickschwefeUiiure,-^ 
Known  only  in  combination  with  ammonia,  potash,  or  soda. 

The  Alkaline  Nitrosulpliaies  are  produced  on  bringing  nitric  oxide  gas 
in  contact  with  alkaline  sulphites,  or  nitric  oxide  gas  and  sulphurous  acid 
gas  in  contact  with  an  alkali,  at  ordinary  temperatures:  an  excess  of 
alkali  promotes  tbe  formation  of  the  compound.  When  the  nitric  oxide 
gas  predominates,  the  alkali  absorbs  2  measures  of  nitric  oxide  gas  for 
every  measure  of  sulphurous  acid,  (consequently  equal  numbers  of  atoms, 
since  sulphurous  acid  gas  is  monatoinic,  and  nitric  oxide  gas  di-atomic; 
vid,  I.,  66).  An  excess  of  nitric  oxide  gas  remains  unabsorbed;  but 
when  an  excess  of  sulphurous  acid  gas  is  present,  an  alkaline  sulphite 
is  formed  in  addition  to  the  nitrosulphate.  (Pelouze.) 

The  compounds  are  colourless  and  crystalline.  The  composition  of  the 
ammoniacal  salt  is  NH*0,NO«,SO^;  that  of  the  potash  salt,  KO,NO*,SO', 
Sir  H.  Davy,  who  first  obtained  these  compounds,  was  of  opinion  that 
nitric  oxide  gives  up  1  atom  of  oxygen  to  the  sulphurous  acid,  and  that 
a  mixture  of  alkaline  sulphate  and  a  compound  of  nitrous  oxide  with  the 


SULPHATE  OP  NITRIC  OXIDE.  445 

alkali  is  obtained^  which  compound  he  called  NitroxU.  Pelouze  demon- 
titrated,  however,  that  the  compounds  crystallize  entire.  With  respect  to 
the  manner  in  which  the  sulphur,  nitrogen,  and  oxygen  are  combined  in 
these  compounds,  the  following  views  may  be  taken: — 1.  It  may  be 
NO',  SO*,  or  sulphite  of  nitric  oxide. — 2.  It  may  be  NO,  SO',  or  sulphate 
of  nitrous  oxide. — 3.  Or  it  may  be  N,  SO*,  a  peculiar  acid  of  nitrogen, 
corresponding  to  nitric  acid,  with  1  atom  of  oxygen  replaced  by  1 
atom  of  sulphur.     The  last  theory  is  that  which  is  adopted  by  Pelouze. 

The  ammoniacal  salt  gradually  evolves  nitrous  oxide  gas  at  ordinary 
temperatures,  and  leaves  sulphate  of  ammonia.  The  potash-salt  is  resolved, 
at  a  temperature  of  130%  into  nitric  oxide  gas  and  sulphite  of  potash.  All 
acids,  even  carbonic  acid,  convert  these  compounds  into  nitrous  oxide  gas 
and  a  salt  of  sulphuric  acid;  many  other  substances  act  in  the  same  way  ^vid. 
Nitros\ilphate  of  Ammonia  and  Potash.) — An  aqueous  solution  of  tnese 
compounds  does  not  decolorize  sulphate  of  manganic  oxide;  hence  they  do 
not  contain  sulphurous  acid.  (Pelouze.) — This  is  not,  however,  conclusive, 
because  the  sulphate  of  manganic  oxide  is  always  very  acid,  and  therefore 
immediately  converts  the  nitrosulphuric  acid  into  nitrous  oxide  and  sul- 
phuric acid.  (Persoz.)  The  solution  does  not  decolorize  solution  of  indigo, 
and  consequently  contains  no  nitric  acid.  (Pelouze.) — This  is  likewise 
inconclusive;  for  the  nitrates  decolorize  solution  of  indigo  only  on  the 
addition  of  an  acid.  (Persoz.)  The  solution  does  not  render  baryta  water 
turbid,  but  gives  a  precipitate  with  nitrate  of  baryta,  which,  after  being 
washed  with  water  containing  pota«h,  is  found  to  be  soluble  in  nitric 
acid,  and  is  therefore  not  sulphate  of  baryta.  (Pelouze.) 

5.    Sulphate  op  Nitric  Oxide.    N0',2S0'. 

Formation, — 1.  Anhydrous  sulphuric  acid  absorbs  dry  nitric  oxide 
gas.  (Aime,  H.  Rose,  Kuhlmann.) — 2.  When  liquid  sulphurous  acid  is 
shaken  up  with  liquid  hyponitric  acid  in  a  sealed  glass  tube,  at  ordinary 
temperatures,  heat  is  evolved,  and  a  greenish  opaque  mixture  formed, 
which  deposits  sulphate  of  nitric  oxide  in  the  form  of  a  yellowish  white 
substance.  The  solid  matter  continues  to  increase,  so  that  the  mixture 
solidifies  in  the  course  of  24  hours  to  within  -^  of  the  whole,  while  the 
remaining  -^  forms  a  greenish  liquid,  which,  on  opening  the  tube,  vola- 
tilizes in  red  vapours  with  great  violence,  and  bursts  the  tube,  unless  it  is 
surrounded  with  a  freezing  mixture.  (Prevostaye.) 
NO<  +  2SO«  =  N0«,  2SO'. 

The  greenish  explosive  liquid,  Prevostaye  supposes  to  be  nitrous  acid ; 
but,  according  to  his  observations,  an  explosion  takes  place  on  opening  the 
tube,  even  after  cooling  the  compound  by  means  of  a  freezing  mixture; 
whereas  the  boiling  point  of  nitrous  acid  is  certainly  not  far  below  — 10°, 
and  moreover  nitrous  acid  is  of  a  blue  colgur:  hence  the  explosive  liquid 
requires  further  investigation.  According  to  Prevostaye,  sulphurous  acid 
and  hyponitric  acid  do  not  act  on  each  other  in  the  gaseous  form;  and  not 
even  in  the  liquid  state  under  the  ordinary  atmospheric  pressure. — 3.  When 
anhydrous  sulphuric  acid  is  brought  in  contact  with  liquid  sulphurous  and 
hyponitric  acids,  this  compound  is  immediately  formed.  (Prevostaye.)  [Is 
there  not  in  this  case  any  free  sulphuric  acid  left?] 

Preparation, — 1.  Nitric  oxide  gas  dried  by  means  of  chloride  of  cal- 
cium is  passed  over  anhydrous  sulphuric  acid  as  long  as  it  is  absorbed. 


446  NITROGEN* 

Tbe  crust  of  the  compound  vhicli  forms  prevents  the  sulphuric  acid 
beneath  from  being  saturated  with  gas.  (H.  nose.)— 2.  Into  one  arm  of  a 
W-shaped  gkss  tube  liquid  sulphurous  acid  is  introduced,  and  into  the 
other  arm  hyponitric  acid,  the  two  gases  being  in  nearly  equal  volumes. 
Both  ends  are  then  sealed,  and  the  two  liquids,  previously  cooled  by  a 
powerful  freezing  mixture,  are  shaken  together.  After  three  days  the 
tube  is  opened,  after  being  first  cooled  in  a  freezing  mixture  to  prevent 
explosion;  and  when  the  vapour  of  the  greenish  liquid  is  entirely  expelled, 
it  is  again  sealed  and  heated  in  an  oil  bath  to  120^  (248''  F.}.  It  is  then 
reopened — upon  which  fresh  red  vapours  escape,  arising  from  portions  of 
the  greenish  liquid  enclosed  in  the  solid  compound;  sealed  once  more; 
heated  till  the  compound  is  completely  fused,  which  takes  place  at  about 
230**  (446^  F.);  and  finally  left  to  cool  (Prevostoye.) 

Properties. — Crystallizes  after  fusion  in  regular  rectangular  prisms, 
often  with  two  opposite  lateral  edges  truncated ;  or  in  a  white  mafis  of 
silky  needles,  sp.  gr.  :=  2'14.  At  217°  it  begins  to  melt,  and  becomes 
perfectly  fluid  at  230®.  When  the  compound  has  absorbed  moisture  from 
the  air,  the  melting  point  is  lower.  The  fused  compound  when  near  its 
boiling  point  is  yellowish  red,  like  hyponitric  acid;  at  230**  it  is  yellow. 
It  begins  to  solidify  at  217°;  at  190°  the  solid  mass  is  transparent;  below 
this  temperature  it  appears  opaque  and  greenish  yellow,  and  is  white  only 
when  perfectly  cold.  The  compound  boils  nearly  at  the  same  temperature 
as  mercury,  and  distils  over  without  decomposition.  It  stains  the  ekin 
dark  red  first,  then  yellow,  and  then  sliffhtly  blackish.  ^Prevostaye.) — 
White,  hard,  does  not  fume  in  the  air;  when  heated  it  melts,  and  maybe 
sublimed  unchanged.  (H.  Rose.) 
Calculation,  (acoordiog  to  H.Rose.)  H.Rose.        Or:  Prevostaye. 

NO«    30  27-27  N  14  12-73  11-79 

2S0*  80  72-73     71-64 2S  32  29-09  27-18 

80 64  58-18  6103 

NO*,2SO'  110  10000  110  10000  10000 

Prevostaye  regards  this  compound  (as  in  fact  it  was  formerly  regarded) 
as  bisulphate  of  nitrous  acid,  or  rather  as  NO*,  SO'  +  SO';  according  to 
this,  it  must  contain  IN,  2S  and  90,  with  which  its  analysis  agrees. 
H.  Rose's  view,  however,  is  the  more  probable. 

Decompositions,^!,  Sulphate  of  nitric  oxide  dissolves  rapidly  in 
water,  nitric  oxide  gas  being  evolved,  and  aqueous  sulphuric  acid 
remaining.  When  air  is  present,  the  nitric  oxide  gas  evolved  forms 
red  vapours,  and  the  liquid  is  found  to  contain  a  small  quantity  of  nitric 
acid.  Sulphate  of  nitric  oxide  deliquesces  in  the  air,  forming  a  permanent 
colourless  liquid,  which,  however,  gives  off  red  vapours  in  contact  with 
the  moisture  of  the  air.  (H.  Rose.)  It  emits  hyponitric  acid  fumes  in  the 
air,  but  its  decomposition  takes  place  slowly, because  the  hyd rated  sulphuric 
acid  produced  protects  tbe  remaining  portions  from  contact  with  the  air. 
(H.  Rose.)  One  gramme  of  the  compound  mixed  with  water  evolves 
at  most,  only  50  cubic  centimetres  of  nitric  oxide,  and  the  liquid  still 
retains  the  odour  of  the  gas.  (Prevostaye.)  With  aqueous  solutions  of 
salts  and  alkalis,  sulphate  of  nitric  oxide  behaves  as  with  water;  a  solu- 
tion of  ferrous  sulphate  colours  the  smallest  traces  of  the  compound, 
brown.  (H.  Rose.) — 2.  Anhydrous  baryta  does  not  act  on  the  compound 
at  ordinary  temperatures ;  when  heated  it  becomes  incandescent,  and  is 
converted  into  sulphate  of  baryta^  with  disengagement  of  red  vapours. 


SULPHATE  OF  NITRIC  OXIDE.  447 

(Prevostaye.) — 3.  Mercury  also  does  not  affect  it  at  ordinary  tempe- 
ratures; when  heated,  it  disengages  a  mixture  of  nitric  oxide  and  sul- 
phurous acid  gas,  and  yields  mercuric  sulphate.  (Prevostaye.) — 4.  It  fuses 
in  a  current  of  ammoniacal  gas,  producing  great  rise  of  temperature,  and 
forming  a  mass  which  is  yellowish  at  first,  but  afterwards  turns  white ; 
when  completely  saturated  with  ammonia  the  new  compound  behaves 
like  ordinary  sulphate  of  ammonia  (NH*,  HO,  SO")  with  a  slight  excess  of 
sulphuric  acid.  Hence  water  must  have  been  formed  [and  nitric  oxide 
disengaged.]  (H.  Rose).  Prevostaye,  on  passing  ammoniacal  gas  through 
the  fused  compound,  obtained  acid  sulphate  of  ammonia,  with  evolution 
of  nitric  oxide  gas. — 5.  It  converts  alcohol  into  nitrous  ether  without  the 
least  disengagement  of  red  fumes.  (H.  Rose.) 

Sulphate  op  Nitric  Oxide  combined  with  Hydratbd  Sulphuric 
Acid. — a.  Crystallized. — Formation  and  Preparation. — 1.  By  dissolving 
snlphate  of  nitric  oxide  in  a  small  quantity  of  hot  oil  of  vitriol.  The  green- 
ish yellow  solution  solidifies,  on  cooling,  to  a  translucent,  nearly  colourless 
mass.  (Prevostaye.) — 2.  Oil  of  vitriol  left  in  contact  with  nitric  oxide 
gas  for  a  period  of  two  months,  absorbs  it  gradually  in  such  quantities, 
that  white  scaly  crystals  are  produced.  (0.  Henry  &  Plisson,  Ann.  Chim, 
Phys.  46,  197.)  According  to  Berzelius  and  Gay-Lussac,  oil  of  vitriol 
does  not  absorb  nitric  oxide  gas. — 3.  A  mixture  of  oil  of  vitriol  and 
byponitric  acid  yields  the  crystallized  compound,  together  with  a  liquid 
consisting  of  sulphuric  and  nitric  acids. — 3N0*  is  resolved  into  NO* — 
which,  in. combination,  with  sulphuric  acid  and  water,  forms  the  crystals — 
and  2 NO*,  which,  with  the  oil  of  vitriol,  forms  the  mother  liquio.  Gay- 
Lussao  obtained  four-sided  prisms  by  this  process. — The  formation  of 
crystals  proceeds  more  slowly  in  the  latter  case — in  consequence  of  a 
larger  quantity  of  nitric  acid  being  produced  —  than  when  hydrated 
sulphurous  acid  is  mixed  with  byponitric  acid.  If  the  vessel  in  which  the 
oil  of  vitriol  and  byponitric  acid  are  mixed  is  filled  with  nitric  oxide  gas, 
crystals  are  formed  immediately.  Anhydrous  sulphuric  acid  mixes  with 
byponitric  acid  without  any  reaction  j  but,  on  the  cautious  addition  of  a 
small  quantity  of  water,  a  portion  of  byponitric  acid  volatilizes,  and 
crystals  are  deposited ;  but  however  small  the  quantity  of  water  added, 
a  liquid  compound  invariably  forms  at  the  same  time.  (Gaultier  de  Clau- 
bry.) — Highly  concentrated  oil  of  vitriol  absorbs  from  a  mixture  of  oxy- 
gen and  nitric  oxide  gases,  4  times  its  bulk  of  the  former,  and  frequently 
more  than  4  times  its  bulk  of  the  latter,  and  at  the  same  time  becomes 
red  and  deposits  crystals.  (Bussy.) — When  the  vapour  of  byponitric  acid, 
evolved  by  heating  a  mixture  of  1  part  of  starch  and  1 0  parts  of  nitric 
acid  of  specific  gravity  1*3,  is  passed  through  ordinary  oil  of  vitriol, 
it  is  absorbed;  and  the  oil  of  vitriol,  which  assumes  a  yellowish  green 
colour,  yields,  on  being  shaken  after  some  hours,  a  white  crystalline 
mass  and  a  mother-liquor  containing  oil  of  vitriol  and  nitric  acid,  besides 
a  portion  of  the  crystallized  compound  in  solution.  (A.  Rose.) — The 
vapour  of  anhydrous  sulphuric  acid  when  brought  in  contact  with  fuming 
nitric  acid,  gives  rise  to  the  formation  of  crystals  and  of  a  liquid,  (Dobe- 
reiner.) — 4.  Highly  concentrated  sulphuric  acid  decomposes  nitric  acid,  at 
a  somewhat  elevated  temperature,  into  oxygen  gas  and  nitric  oxide,  which 
combines  with  the  sulphuric  acid. — Mono-hydrated  nitric  acid,  HO,  NO*, 
kept  cool  by  a  freezing  mixture,  absorbs  the  vapour  of  anhydrous  sul- 
phuric acid  in  great  abundance.  When  the  licjuid  thus  obtained  is 
distilled,  it  first  eyolyes  oxygen  gas  andhyponitnc  acid  vapour;  after- 


448  NITROGEN. 

wardfi  white  needles  sublime;  and  the  residual  liquid  is  a  solution  of 
sulphate  of  nitric  oxide  in  oil  of  vitriol.  (Kuhlmann.) — When  oil  of  vitriol 
is  mixed  with  concentrated  nitric  acsid  so  slowly  that  no  heat  is  evolved, 
the  two  acids  appear  to  mix  without  alteration.  The  mixture  when 
rapidly  heated  in  a  retort,  gives  off  red  vapours  [and  oxygen  gas?]  at 
fir8t,--After  which,  sulphuric  acid  containing  nitric  acid  distils  over,  and 
lastly  pure  sulphuric  acid ;  the  residue  is  a  solution  of  sulphate  of  nitric 
oxide  in  oil  of  vitriol.  (A.  Rose.) — 5.  A  mixture  of  sulphurous  acid  with 
byponitric  acid  and  water,  yields — apparently  with  disengagement  of 
gas — ^the  crystalline  compound  of  sulphate  of  nitric  oxide  with  hydrated 
sulphuric  acid.  Sulphurous  acid  has  no  action  on  nitric  oxide  gas,  nor  on 
the  hyponitric  acid  vapour  produced  on  the  admission  of  atmospheric  air 
or  oxygen  gas,  as  long  as  water  is  not  present;  a  small  quantity  of  water 
causes  the  mixture  to  condense  and  form  the  crystalline  compound.  (H. 
Davy.)  The  crystals  obtained  in  this  manner  are  sometimes  violet- 
coloured,  probably  because  the  nitric  oxide  gas  when  evolved  from  cop- 
per, carries  a  portion  of  copper  with  it. — Moist  sulphurous  acid  gas 
produces  the  crystalline  compound  with  liquid  hyponitric  acid ;  the  hypo- 
nitric  acid,  however,  gives  off  a  small  quantity  of  nitrogen  ^as  in 
solitary  bubbles,  and  a  green  mother-liquor  containing  hyponitric  and 
nitric  acids  remains  over  the  crystals.  Liquid  sulphurous  acid  mixes 
with  hyponitric  acid  at  —  20^  without  further  action ;  but  on  the  addition 
of  a  single  drop  of  water,  a  violent  disengagement  of  gas  takes  place,  and 
crystals  are  formed,  to  which  a  small  quantity  of  nitric  acid  adheres. 
(Gaultier  de  Claubry.)  When  a  mixture  of  1  atom  of  nitre  and  2  atoms 
of  oil  of  vitriol  is  distilled  in  a  cast-iron  vessel,  a  white  crystalline  mass  is 
deposited  in  the  receiver  towards  the  end  of  the  process;  and  this,  on  the 
addition  of  water,  evolves  nitric  oxide  gas — doubtless  in  consequence  of 
the  iron  having  reduced  a  portion  of  the  sulphuric  acid  to  sulphurous  acid, 
which  then  acts  on  the  red  vapours.  (Scanlan,  Kastn,'Arch,  9,  405; 
vid.  also  Bernhardt,  ToKhenh,  1780,  41.) 

The  presence  of  oil  of  vitriol  manifestly  promotes  the  formation  of  the 
sulphate  of  nitric  oxide. 

In  order  to  purify  the  crystals  from  the  mother-liquor  of  sulphuric 
and  nitric  acids,  Gaultier  de  Claubry  washes  them  repeatedly  with  hypo- 
nitric acid ;  after  which  he  introduces  them  into  a  tube,  and  passes  dry 
air  through,  at  a  temperature  between  20''  and  30°,  to  expel  the  hyponi- 
tric acid. 

Properties,  Four-sided  prisms  (Gay-Lussac) ;  or  laminated,  feathery, 
or  granular  crystallized  masses;  colourless,  transparent  or  translucent. 
When  gently  heated,  it  fuses  to  an  oily  liquid ;  the  larger  the  quantity 
of  oil  of  vitriol  present,  the  lower  is  the  temperature  required ;  the  com- 
pound fused  at  60°  may  be  cooled  down  to  10°  if  kept  at  rest,  and  then 
on  being  shaken  solidifies  with  disengagement  of  heat.  (Prevostaye.) 
The  heat  evolved  causes  partial  decomposition,  according  to  Henry, 
Gaultier,  and  Thomson,  {yid,  seq,)  This  substance  stains  the  hand  yel- 
low. (W.  Henry.) 

Approximate  Calculation.  W.  Henry.      Gaultier.     Thomson. 

a,  a.  a, 

NO"     30  17-86  10-32  18*89  12-08 

3S0'   120  71-43  6800  65*59  83-39 

2HO    18  10-71  21-68  15-52  4-53 

NO«, 2S0^~+  2H0rS0\..."  168".'."   100-00  ..."lOO-OO^^.. 100^00  .....".100-00 


SULPHATE  Of  NiralC  OXIDE.  449 

W.  Henry.  Gaultier.  Thomson. 

6.  b,  b, 

N0»      1307     23-96  NO*    21-75 

SO'       68-00     65-59  SO«      66*70 

HO       18-93     1010  HO      1155 

10000     99-65  100-00 

Heniy  and  Gaultier  are  of  opinion  that  the  compound  contains  nitrous 
acid;  sulphuric  acid,  and  water ;  Thomson  thinks  tnat  it  contains  nitric 
acid,  sulphurous  acid,  and  water;  in  accordance  with  which,  thej  have 
given  the  analyses  placed  under  b;  the  water  was  estimated  by  loss  only. 
From  the  results  obtained,  the  author  has  calculated  the  analyses  under 
a,  on  the  assumption  that  the  compound  contains  nitric  oxide.  The 
analyses  agree  so  little  with  each  other,  that  no  definite  formula  can  be 
calculated.  The  want  of  uniformity  is  owing  to  the  difficulty  of  obtain- 
ing the  compound  free  from  mechanically  combined  sulphuric  acid,  nitric 
acid,  and  water.  According  to  Gaultier  s  analysis,  an  additional  atom  of 
water  should  be  assigned  to  the  compound. 

JDeeomposUuyns, — 1.  The  crystals  are  decomposed  by  heat  into  nitric 
oxide  gas  and  a  solution  of  sulphate  of  nitric  oxide  in  excess  of  oil  of 
vitriol.  At  a  temperature  of  50°  they  begin  to  give  off  nitric  oxide  gas 
and  hyponitric  acid  vapour ;  at  90°  tnese  products  are  evolved  in  greater 
abuncmnce.  The  crystals  soften  at  lOO"",  and  fuse  completely  between  120° 
and  130^,  disengaging  at  the  same  time  a  large  quantity  of  hyponitric  acid 
vapour ;  at  200°,  the  liquid  evolves  a  small  quantity  of  nitric  acid ;  at  280" 
it  is  highly  transparent,  and  of  a  yellowish-red  colour,  and  evolves  more 
nitric  acid;  at  the  boiling  point  of  mercury,  nearly  colourless  oil  of  vitriol 
distils  over,  and  on  the  addition  of  water  to  this  liquid,  nitric  oxide  gas 
is  evolved.  (Gaultier.)  The  crystals  remain  undecomposed  at  104-4°, 
and  at  138"^  they  give  off  nitric  oxide  gas;  but  even  after  the  heat  haa 
been  raised  to  205°,  a  liquid  remains  which  still  evolves  a  large  Quantity 
of  nitric  oxide  gas  on  the  addition  of  water.  (W.  Henry.  J — 2.  Tne  crys- 
tals dissolve  rapidly  in  water,  with  disengagement  of  neat  and  nitric 
oxide  gas,  yielding  ailute  sulphuric  acid,  which  still  retains  a  large  portion 
of  the  nitric  oxide  in  solution ;  on  boiling  the  liquid,  however,  the  nitric 
oxide  is  expelled.  In  contact  with  air,  the  nitric  oxide  gas  evolved  forms 
red  vapours,  which  are  partially  absorbed  by  the  aqueous  solution  and 
form  nitric  acid.  The  solution,  when  prepared  in  a  close  vessel  and 
boiled  for  some  time,  is  free  from  nitric  oxide,  and  contains  little  or 
no  nitric  acid  Tthe  presence  of  the  latter  is  recognised  by  the  liquid 
ffiving  a  red  colour  with  ferrous  sulphate  and  oil  of  vitriol,  p.  182, 
but  not  decolorizing  hypermanganate  of  potash) ;  the  nitric  acid  when 
present,  doubtless  arises  from  portions  of  mother-liquor  adhering  to  the 
crystals;  but  a  solution  formed  in  contact  with  air,  contains  nitric 
acid.  (A.  Rose.)  100  parts  of  the  crystals  dissolved  in  water  in  a 
retort  evolve  1208  parts  of  nitric  oxide  gas;  the  resulting  solution  is 
free  from  nitric  acid.  (Thomson.)  On  dissolving  the  crystals  in  water, 
the  rise  of  temperature  amounts  to  more  than  33°;  100  parts  of  the 
crystals  disengage  in  this  manner  5-273  parts  of  nitric  oxide  gas,  of  which 
one  half  is  set  free  immediately,  and  the  other  half  on  boiling ;  the  re- 
maining liquid  still  contains,  besides  9*31  parts  of  nitric  acid,  68  parts  of 
sulphuric  acid  [did  the  air  have  access  to  it?]  (W.  Henry.)  When  the 
crystals  are  exposed  to  the  air,  they  first  become  pasty,  and  then  deli- 
quesce, giving  off  red  vapours,  and  yielding  an  oily  liquid  which  con- 
TOL.  II.  2  a 


450  NITROGSN. 

tains  salphurie,  nitrio,  and  nitrous  acids  [nitric  6xide].  (Gaultier.) 
The  crystals  when  dissolved  in  water  erolye  red  rapours  even  in  an 
atmosphere  of  carbonic  acid,  hydrogen,  or  nitrogen  gas,  though  in  smaller 
quantity  than  in  the  air;  the  solution  appears  blue  at  first,  then  green, 
and  lastly  yellow.  When  laid  on  snow,  the  crystals  melt,  sinking  into 
the  snow  like  red-hot  iron  and  imparting  to  it  a  dark  blue  colour :  at  the 
same  time,  the  temperature  falls  as  much  perhaps  as  from  —  1°  to  —  26*7^^ 
At  —  26*7°,  no  further  action  takes  place.  (Dana.) — 3.  When  heated  with 
roa^esia,  the  crystals  are  decomposed,  the  whole  mass  becoming  red-hot : 
with  baryta,  the  action  is  still  more  yiolent,  the  mass  being  projected 
from  the  vessel.  (Gaultier.)  When  rubbed  up  in  a  mortar  with  bicar^ 
bonate  of  potassa,  the  crystals  first  yield  a  dry  mixture,  and  evolve 
nitric  acid  fumes  [Nitric  oxide  gaslj;  on  continuing  the  rubbing,  a 
pasty  mass  is  produced,  which  in  addition  to  sulphate  and  carbonate  of 
potash,  contains  a*-  minute  quantity  of  nitrate.  With  carbonate  of  am- 
monia the  crystals  may  be  triturated  without  undergoing  decomposi- 
tion. (Thomson.) — 4.  When  heated  with  mercury,  the  crystals  yield 
sulphate  of  mercuric  oxide  with  sulphurous  acid,  nitric  oxide,  and 
nitrogen.  (Gaultier  de  Claubry.) 

fi.  Liquid  Compound. — 1.  Sulphate  of  nitric  oxide  dissolves  abund- 
antly in  cold  oil  of  vitriol.  (H.  Rose.)  It  does  not  dissolve  in  cold, 
and  but  slowly  in  hot  oil  of  vitriol.  (Prevostaye.) — 2.  The  crystalline 
compound  of  sulphate  of  nitric  oxide  and  hydrated  sulphuric  acid  readily 
dissolves  in  oil  of  vitriol,  (Graultier);  according  to  Dan%  very  slowly. 
— 3.  The  liquid  compound  is  also  formed  when  an  excess  of  oil  of  vitriol 
is  present  in  any  of  the  various  methods  of  preparing  the  crystalline  com- 
pound (pp.  447,  448).  Dobereiner  partially  distils  3  parts  of  anhydrous 
sulphuric  acid  or  fuming  oil  of  vitriol  with  i  part  of  fuming  nitric  acid;  the 
residue  in  the  retert  is  the  liquid  compound.  A.  Rose  passes  the  vapour 
disengaged  by  heating  1  part  of  starch  with  10  parts  of  nitric  acid  of 
specific  gravity  1*3,  inte  oil  of  vitriol. — 4.  Remains  in  the  retort,  on  dis- 
tilling the  crystalline  compound.  Berzelius  prepared  it  in  this  manner^ 
and  regarded  it  as  sulphate  of  nitric  acid. 

Oily  liquid,  of  specific  gravity  r887  (Dobereiner),  between  1*94  and 
1  '96  (Berzelius) ;  colourless  at  ordinary  temperatures,  bright  yellow  when 
hot;  has  a  slight  odour.  (Dobereiner.)  Colourless  at  ordinary  tempe- 
ratures, greenish  yellow  while  hot  (Prevostaye);  colourless  at  ordinary 
temperatures,  yellowish  when  hot;  does  not  fume  in  the  air.  (H.  Rose.) 

When  separated  inte  two  equal  parts  by  distillation,  the  distillate  con* 
tains  less  nitrous  acid  [nitric  oxide]  than  the  residue  in  the  retort  When 
mixed  with  water,  it  evolves  nitric  oxide  gas  attended  with  great  rise  of 
temperature.  When  lime,  magnesia,  or  hydrate  of  potash  is  mixed  with 
the  liquid,  great  heat  is  evolved,  nitric  oxide  gas  escapes  with  violent 
effervescence,  forming  hyponitric  acid  by  contact  with  the  air,  and  a 
sulphate  of  the  base  is  produced.  Heated  with  nitre,  it  froths  up  vio- 
lently and  evolves  hyponitric  acid  fumes.  Phosphorus  inflames  in  it  at  s 
temperature  of  62°,  and  emits  red  sparks.  When  distilled  with  sulphur, 
it  yields  nitric  oxide,  sulphurous  acid,  and  a  white  sublimate.  Sulphuret- 
ted hydrogen  precipitates  sulphur,  first  red,  and  afterwards  yellow, 
with  rapid  disengagement  of  sulphurous  acid  gas;  if  water  be  then  added, 
nitric  oxide  and  nitrogen  gases  are  evolved.  Zinc,  iron,  copper,  mercury, 
and  silver  are  oxidized  by  the  liquid,  and  colour  it  either  purple,  red 
(sulphide  of  iron  gives  the  finest  red),  or  violet-blue  (the  finest  is 
obtained  with  copper).  (Dobereiner.)     During  the  solution  of  the  inetaJs, 


jj 


HYDROSULPHATE  OP  AMMONIA.  451 

Aitrio  oxide  ffas  is  disengaged.  (Berzelins.^  Protochloride  of  iron  is  ren- 
dered dark  Irown  and  opaque  by  the  liquid.  The  liquid  compound  is 
also  decomposed  by  starch,  sugar,  alcohol,  and  ether.  (Dobereiner.)  When 
heated  with  sulphate  of  ammonia  to  160^,  it  eyolves  pure  nitrogen  gas. 
(Pelouze.) 

Sulphuric  acid  of  specific  gravity  1*6  dissolves  the  crystals  with  great 
difficulty,  disengaging  a  small  quantity  of  red  vapour.  At  15' 5°,  the  pale- 
yellow  solution  evolves  gas  which  is  again  absorbed  at  a  lower  tempera- 
ture. (Dana.) 

Upon  the  formation  of  sulphate  of  nitric  oxide  and  its  combination 
with  oil  of  vitriol,  is  founded  the  Preparation  of  Englisk  Oil  of  Vitriol, 

1.  Sulphur  is  burned  with  about  \  of  its  weight  of  nitre;  whereby 
nitric  oxide  and  sulphurous  acid  are  evolved,  and  sulphate  of  potaeli 
remains  behind — ^probably  in  the  following  manner  : 

KO,NO*  +  SO  =  KO,SO'  +  NO«. 

2.  Nitric  acid  is  placed  in  shallow  dishes  in  the  leaden  chamber,  into 
which  the  sulphurous  acid  ^as  is  conveyed;  or  it  is  made  to  enter  the  cham- 
ber in  the  form  of  vapour,  being  evolved  by  heating  a  vessel  containing  a 
mixture  of  sulphuric  acid  and  nitrate  of  potash  or  soda,  in  the  flame  of 
the  burning  sulphur.  The  nitric  acid  is  decomposed  by  a  portion  of  the 
sulphurous  acid  into  sulphuric  acid  and  nitric  oxide  gas  : 

NO*  +  3S0«  =  NO«  +  3SO'. 

3.  A  mixture  of  nitric  oxide  gas  and  hyponitrio  acid  vapour,  evolved 
by  heating  sugar,  syrup,  &c.  with  nitric  acid,  is  passed  into  the  leaden 
chamber.  In  all  these  cases,  sulphurous  acid  gas,  hyponitric  acid  vapour 
—formed  from  the  nitric  oxide  gas  and  the  oxygen  of  the  air — and  aque- 
ous vapour,  introduced  for  the  purpose,  mix  together  in  the  leaden  cham- 
ber. By  the  mutual  action  of  these  substances,  there  is  formed  a  crystal- 
line compound  of  sulphate  of  nitric  oxide  with  oil  of  vitriol,  which  falls 
in  dense  white  clouds  to  the  bottom  of  the  leaden  chamber,  where  it  meets 
with  water  purposely  placed  there,  and  is  resolved  into  sulphuric  acid 
which  is  absorbed  by  the  water  and  nitric  oxide  gas  which  escapes.  The 
nitric  oxide  thus  set  free  takes  up  a  fresh  portion  of  oxygen  from  the  air, 
and  again  forms  hyponitric  acid  vapour,  which,  as  before,  combines  with 
sulphurous  acid,  and  produces  another  portion  of  the  crystalline  com- 
pound, &c. 

According  to  Knhlmann,  anhydrous  sulphuric  acid  is  capable  also  of 
combining  with  nitrotu  and  with  hyponitric  acid. 

On  distilling  a  mixture  of  oil  of  vitriol  and  concentrated  nUrie  acid, 
nitric  acid  (with  oxygen  gas  %)  is  first  evolved,  and  then  pure  oil  of  vitriol 
distib  over;  the  residue  contuns  sulphate  of  nitric  oxide.  (A.  Rose.) 

C.      a.      MoNO-HYDROSULPaATB  OF  AmHONIA. 

Monotulphide  of  Ammonium.  A  mixture  of  1  volume  of  hydrosul- 
phuric  acid  gas  with  rather  more  than  2  volumes  of  ammoniacal  gas,  is 
passed  into  a  tube  cooled  down  to  — 18^  At  ordinary  temperatures,  the 
two  gases  combine  only  in  equal  volumes,  producing  bi-hyarosulphate  of 
ammonia.  Berzelius  recommends  the  subbmation  of  a  mixture  of  sal- 
ammoniac  and  monosulphide  of  potassium,  the  latter  not  being  in  excess; 
according  to  the  observation  of  Bineau,  however  (vid,  seq,),  the  product 
will  be  mono-hydrosulphate  or  bi-hydrosulphate  of  ammonia,  accoiding  as 
the  receiver  is  cooled  to  —18**  or  not. 

2  Q  2 


432  NITROGEN. 

Colourless  crystals,  having  a  strong  alkaline  action,  and  at  ordinary 
teraperatnres  immediately  eyolving  half  their  ammonia  in  the  gaseona 
form.  (Bineau,  Ann.  Chim.  Phyi.  70,  261.)  An  aqneous  solution  of  the 
salt  is  obtained  by  dividing  u  quantity  of  aqueous  ammonia  into  two 
equal  parts,  saturating  one  with  hydrosulphuric  acid  gas,  and  then  adding 
the  other  half.  Colourless  alkaline  liquid,  smelling  of  hydrosulphuric 
aicid  and  ammonia;  rapidly  decomposed  on  exposure  to  the  air  (p.  225.) 

CalcaUtion.  Vol. 

NH«  17  50  Ammonutcal  gas    2 

HS 17  50  Hydrosulpharic  acid  gas     1 

NH',HS   34  100 


b,      Bl-HYDROSULPHATE   OP   AmMONIA. 

Double  Sidpkide  of  Hydrogen  and  Ammonium.  Sidph-hydraie  of  Am- 
fnonia.  At  ordinary  or  at  elevated  temperatures,  hydrosulphuric  acid 
and  ammoniacal  gas  invariably  combine  m  equal  volumes,  in  whatever 
proportions  they  may  be  mixed.  (Bineau,  A  nn.  Ckim.  Phys.  67,  230 ;  68, 
435.)  The  two  gases  are  made  to  pass  in  equal  volumes  into  a  vessel 
surrounded  with  ice,  and  previously  filled  with  hydrogen  or  ammoniacal 
gas.  The  compound  crystallizes  in  colourless  needles  and  scales;  it  vola- 
tilizes and  sublimes  even  at  ordinary  temperatures;  has  a  penetrating 
odour  of  ammonia  and  of  hydrosulphuric  acid,  and  an  alkaline  action. 
Rapidly  turns  yellow  in  the  air,  from  formation  of  pentasulphide 
of  ammonium.  (Tbenard.)  The  salt  yields  a  colourless  solution  with 
water.  The  same  solution  is  obtained  by  saturating  aqueous  ammonia 
with  washed  hydrosulphuric  acid  gas,  out  of  contact  of  air. 

Calculation.  Vol.  Sp.  gr. 

NH»     17  33-33  Ammoniacal  gas    \  0*29465 

2HS     34  66-67  Hydrosulphuric  acid  gas    4  0*58930 

NH»,2HS  ....  51  100  00  Vapour  1  0*88395 


IT    c.    Hypo-hydrosulphate  op  Ammonia. 

Telra-sulph  ideofA  mmonium.  Formed  by  passing  ammoniacal  gas  and 
hydrosulphuric  acid  alternately  through  a  solution  of  the  pentasulphide  d. 
It  then  separates  as  a  crystalline  mass.  In  its  modes  of  decomposition  it 
resembles  the  penta-sulpbide.  (</.  v.) 

Calculation. 

NH3 17     20-73 

HS     17     20*73 

3S      48     58-54 

NH',HS*  82     100-00 

(Fritzsche,  J,  pr.  Ohem,  Bd.  33,  abstr.  Ann.  Pharm.  52,  230.)   IT 

d.    Hydrosulphitb  of  Ammonia. 

Pentasulphide  of  Ammonium.  Aqueous  solution  of  ammonia  is  satu- 
rated with  hydrosulphuric  acid  gas,  and  sulphur  in  powder  afterwards 
added,  whilst  ammoniacal  gas  is  passed  into  the  liquid.  The  excess  of 
ammonia  is  then  saturated  by  a  current  of  hydrosulphuric  acid  gas ;  the 


SULPHIDES  OF  AMMONIUM.  453 

solution  again  treated  with  salphur  and  ammoniacal  gas,  and  lastly, 
with  hjdrosulphuric  acid  gas.  After  the  final  saturation,  the  solution, 
if  kept  cold,  solidifies  to  a  crystalline  mass;  it  is  then  brought  into 
the  liquid  state  by  heating  to  a  temperature  between  40^  and  50^,  and 
left  to  cool  slowly  in  a  stoppered  bottle.  (Fritzsche.)  The  crystalline 
compound  is  also  obtained  mixed  with  bi-hydrosulphate  of  ammonia, 
when  a  mixture  of  ammoniacal  gas  and  yapour  of  sulphur  is  transmitted 
through  a  red-hot  porcelain  tube.  (Th^nard.) 

Long,  orange-yellow,  oblique  rhombic  prisms.  When  heated,  it  gives 
off  mono-hydrosulphate  of  ammonia,  and  is  converted  into  hepta-sulphide 
of  ammonium ;  similarly,  when  kept  in  a  large  vessel  full  of  dry  atmo- 
spheric air. 

3(NH*S*)  =  2(NH4S')  +  NH*S. 

The  crystals,  if  moist  from  adhering  mother-liquid,  acquire  under  these 
circumstances  a  ruby  colour,  increasing  in  size  at  first  and  becoming  hol- 
low inside.  In  the  open  air,  the  crystals  gradually  exhale  hydrosulohate 
of  ammonia,  and  are  converted  into  a  yellow  mixture  of  crystallizea  sul- 
phur and  hyposulphite  of  ammonia.  This  decomposition  takes  place 
much  more  slowly  in  air  dried  by  means  of  oil  of  vitriol.  The  compound 
dissolves  in  water,  with  separation  of  sulphur,  which  appears  tenacious  at 
first  but  afterwards  becomes  crystalline.  The  compound  dissolves  com- 
pletely in  alcohol,  but  the  solution,  even  when  kept  in  closed  vessels,  depo- 
sits crystals  of  sulphur  under  certain  circumstances.  (Fritzsche.)  The 
solution  obtained  by  saturating  an  aqueous  solution  of  hydrosulphate  of 
ammonia  with  sulphur  at  a  gentle  heat,  is  a  brownish  yellow,  oily  liquid, 
which  does  not  fume  in  the  air,  and  resembles  hydrosulphate  of  ammonia, 
but  has  a  less  powerful  smell. 

Calculation.  FritzBcke. 

NH'  17  17-35  17120 

HS     17  17-35  16-115 

48  64  65-30  64-700 

NH^HS*  ....  98  100-00  97935 

The  loss  in  Fritzsche's  analysis  arose  from  adhering  mother-liquor. 

e,    Hypo-hydbosulphitb  of  Ammonia. 

Heptamlphide  of  Ammonium, — 1.  Formed  by  the  spontaneous  evapo- 
ration of  o;  the  process  succeeds  best  in  a  wide  vessel  containing  dry  air. 
— 2.  If  the  crystals  of  c  are  re-dissolved  in  the  mother-liquor  by  the  aid  of 
heat,  and  the  vessel  containing  the  solution  suffered  to  cool  under  a  large 
receiver,  which  is  ground  to  fit  a  glass  plate,  mono-hydrosulphate  of 
ammonia  escapes  in  bubbles,  and  d  separates  first  in  ruby-coloured 
crystals,  then  c,  and  lastly  d  again.  The  crystals  may  be  preserved  in 
bottles  completely  filled  with  them,  and  protected  from  heat  and  from  the 
sun's  rays;  they  change  when  exposed  to  the  air,  but  not  so  quickly  as 
c.  When  heated  they  evolve  a  lower  sulphide  of  ammonium,  which  is 
deposited  in  yellow  drops  on  the  sides  of  the  vessel,  and  leave  sulphur : 
the  yellow  compound,  on  exposure  to  heat,  yields  a  sublimate  of  very 
volatile  crystab,  probably  consisting  of  bi-hydrosulphate  of  ammonia. 
The  compound  d  assumes  a  brighter  red  colour  when  heated,  and  becomes 
surrounded  with  fused  sulphur  of  a  liffht  yellow  colour,  into  which  the 
whole  compound  is  gradually  converted,  with  violent  ebullition ;  but  the 
still  undecomposed  portion  of  d  neither  fuses  nor  dissolves  in  the  melted 
sulphur.    A  temperature  not  much  higher  than  the  melting-point  of 


454  NITROGEN. 

sulphur  ig  suffioieut  to  decompose  the  salt.  If  the  residual  fused  snlphor 
be  allowed  to  cool  in  an  atmosphere  which  contains  the  vapour  of  hydro- 
sulphate  of  ammonia,  it  re-absorbs  a  large  quantity,  becomes  orange- 
coloured,  and  remains  liquid;  on  the  application  of  heat  it  boils  again. 
The  residue  of  sulphur  amounts  to  75*82  per  cent.  (Fritzsehe,  J.  pr, 
Chem.  24,  460.) 

Calculation.  Fritzsche. 

NH»  17  1308  1300 

HS 17  1308  12-92 

6S  96  73-84  7509 

NH»,HS7    130  lOOOO  10101 

Volatile  Liver  of  Sulphur^  SpirUus  mlphurattu  Beguini,  Liquor 
funians  Boyliiy  may  be  regarded  as  a  mixture  of  hydrosulphate  and 
hydrosulphite  of  ammonia  dissolved  in  water.  It  is  obtained  by  distiUing 
a  mixture  of  1  part  of  sulphur  with  2  parts  of  sal-ammoniac  and  2  or  3 
parts  of  lime.  The  liquid  is  obtained  even  when  all  the  ingredients  aie 
anhydrous ;  so  that  the  hydrogen  required  for  the  formation  of  the  hydro- 
sulphurous  acid  can  only  be  derived  from  the  hydrochloric  acid,  while 
chloride  of  calcium  is  produced,  and  the  oxygen  of  the  lime  combines 
with  a  portion  of  sulphur,  and  forms  sulphuric  acid,  which  is  retained  by 
the  undecomposed  lime.  {Sch»  108.) 

4CaO  +  3(NH»,  HCl)  +  168  =  3CaCl  +  CaO,  80«  +  3(NH».  H8*.) 

But  the  quantity  of  sulphur  which  actually  combines  with  1  atom  of 
hydrogen  is  less  than  5  atoms.  According  to  Gay-Lussac,  free  ammonia 
first  passes  over,  and  then  bi-hydrosulphate  of  ammonia  in  crystals,  which 
afterwards  pass  into  the  liquid  state;  the  residue  contains  chloride  of 
calcium,  sulphate  of  lime,  ana  sulphide  of  calcium ;  no  nitrogen  gas  is  dis- 
engaged. The  liquid  is  also  obtained  when  phosphate  or  sulphate  of 
ammonia  is  used  instead  of  sal-ammoniac  j  in  this  case,  the  hydrogen  is 
derived  from  the  water  contained  in  the  salt.  (Gay-Lussac,  Ann.  Ghim, 
Pkys,  40,  302;  also  Schw,  55,  362;  also  Pogg.  15,  538;  compare  also  E. 
CrelL  Chem.  J,  1,  5Q,  who  obtained  one  part  of  the  distillate  from  1 
part  of  sal-ammoniac;  also  Vauquelin,  Ann.  Ckim,  Pkys.  6,  42.)  If 
slaked  lime  is  employed,  the  product  is  more  abundant  but  not  so  strongly 
concentrated.  The  distillate  is  dark  yellow,  and  fumes  in  the  air  and  in 
oxygen  gas,  but  not  in  hydrogen  or  nitrogen  gas.  The  first  portions  of 
the  distillate,  which  contam  excess  of  ammonia,  have  more  especially  the 

f)ower  of  dissolving  an  additional  quantity  of  sulphur,  whereby  an  oily 
iquid  is  formed  which  no  longer  emits  fumes,  but  deposits  a  portion  of 
its  sulphur  on  the  addition  of  water. 


/.    Hyposulphite  op  Ammonia. 

A  solution  of  the  salt  yields  by  evaporation  a  soft  mass  consisting  of 
sma.ll  needles  (Herschel);  brilliant  white  scales  very  soluble  in  water 
(Zeise,  aScAu?.  41,  183);  when  evaporated  over  oil  of  vitriol,  it  yields 
rhombic  laminsB,  which  on  exposure  to  heat  give  off*  water,  ammonia,  and 
a  sublimate  consisting  of  a  mixture  of  sulphur  with  a  large  quantity  of 
hyposulphite  and  sulphite,  and  a  small  quantity  of  sulphate  of  ammonia; 
the  lamfnas  rapidly  deliquesce  in  the  open  air.  (Rammelsberg,  Pogg,  56, 
298.) 


SULPHITE  OP  AMMON.  455 

Calculation.  RammeUberg. 

3NH»    51  2208 

3S»0« 144  62-34  62*30 

4H0  36  15-58 


3(NH*0,  S«0")  +  HO....  231  10000 


g.      SULPHAMIDE.      NH^SO^ 

The  bisnlpliate  of  tercbloride  of  sulphur  mixed  with  the  oil  of  olefiant 
gas  (p.  342),  fonns  with  anhydrous  ammoniacal  gas,  a  cloud  which  con- 
denses to  a  white  powder.  To  prevent  the  powder  from  being  partially 
fused  and  turned  yellow  by  the  heat  thus  disen£;aged,  it  must  be  artificially 
cooled  from  without  In  order  to  insure  complete  saturation  with  ammo- 
nia, the  mass  is  detached  from  the  sides  of  the  vessel  and  left  in  contact 
with  ammoniacal  gas  for  24  hours.  The  excess  of  ammonia  adhering  to 
the  mass  is  then  removed  by  suspending  it  for  several  hours  in  vacuo  over 
oil  of  vitriol. 

The  extremely  deliquescent  white  powder  thus  obtained^  may  be 
regarded  as  a  mixture  of  sal-ammoniac  and  sulphamide« 
SO*a  +  2NH»  =  NH*C1  +  NH«,SO«. 


Calculation. 

2N 

280  .... 

6.0  .... 

35-4  .... 

32-0  .... 

...     27-61  ... 
....       5-92  ... 
....     34-91  ... 
....     31-56  ... 

Regnanlt. 
27-92 

6H  

CI    

SO* 

616 

34-78 

31-82 

White  Powder   

101-4  .... 

...  100-00  ... 

100-68 

The  powder  is  very  soluble  in  water  and  alcohol;  the  sal-ammoniac  can 
only  be  partially  separated  from  the  solution  by  crystallization.  From 
a  solution  of  the  powder  in  water,  chloride  of  platinum  precipitates  but 
half  the  ammonia,  namely  the  portion  belonging  to  the  sal-ammoniac.  The 
solution  does  not  precipitate  chloride  of  barium  at  ordinary  temperatures, 
even  in  the  course  of  a  year;  a  boiling  heat  promotes  the  precipitation, 
especially  on  the  addition  of  a  stronger  a<;id;  but  after  boiling  the  solu- 
tion for  24  hours  with  chloride  of  barium  and  hydrochloric  acid,  but  little 
more  than  half  the  sulphur  present  is  separated  in  the  form  of  sulphate  of 
baryta;  to  obtain  the  whole  of  the  sulphate  of  baryta,  it  is  necessary  to  eva- 
porate the  mixture  to  dryness  and  redissolve  in  dilute  hydrochloric  acid. 

If  the  chlorine  of  sal-ammoniac  is  precipitated  from  the  solution  by  ni- 
trate of  silver,  the  filtrate  still  gives  no  precipitate  with  nitrate  of  baryta 
at  ordinary  temperatures.  When  the  solution  is  boiled  with  potash  for 
several  hours,  and  the  liquid  afterwards  saturated  with  hydrochloric  acid, 
it  still  gives  but  a  scanty  precipitate  with  chloride  of  li^rium.  A  long 
time  is  therefore  requirea  for  potash  to  convert  sulphite  of  amidogen  into 
sulphuric  acid  and  ammonia.  (Regnaolt,  Ann.  Chim,  Phy9.  69,  170;  also 
J.  pr.  Chem.  18,  98.) 


h,    Anhtdrous  Bibulphitb  op  Ammok. 

SulpkU-Ammon,  •—  Anhydrous  sulphurous  acid  gas  rapidly  con- 
denses with  anhydrous  ammoniacal  gas  to  a  light  brown  mass  which  is 
rendered  colourless  by  water.  (Dbbereiner,  Sckw.  47,  120.)  In  whatever 
proportions  the  two   gases  are  mixed,  they  always  condense  in  equal 


456  NITROGEN.  ^ 

volumes.  The  dirty  yellowish-red  mass  first  obtained  is  conyerted,  when 
kept  for  a  lon^  time  at  ordinary  temperatures,  into  reddish-yellow  needles 
collected  together  in  stellated  masses.  (H.  Rose.) 

Calculation  a.  CaLcnlation  b, 

NH»  17  20-99  NH5  17  20-99 

2S0*  64  7901  SO      24  29-63 

SO»    40  49-38 

NH3,2SO« 81     ...100-00  NH',  SO, SO'     81  10000 

According  to  calculation  a,  the  salt  is  a  compound  of  two  atoms  of 
sulphurous  acid  with  one  atom  of  ammonia;  according  to  calculation  b,  of 
one  atom  of  sulphuric  acid  with  one  atom  of  ammonia  and  one  atom  of 
SO ;  the  SO  would  replace  the  atom  of  HO  as  it  exists  in  ordinary  sul- 
phate of  ammonia.  H.  Rose  supposes  with  probability  that  the  ammonia 
may  be  combined  with  an  isomeric  (or  rather  polymeric)  sulphurous  acid, 
S*0*  or  SO,  SO^  that  is  to  say,  with  an  acid  which  may  be  regarded  as 
a  compound  of  hyposulphurous  and  sulphuric  acid.  Be  this  however  as  it 
may,  the  remarkable  colour  of  the  salt  indicates  a  peculiar  composition ; 
and  the  singular  changes  which  it  undergoes,  show  the  great  tendency  of 
the  acid  contained  in  the  salt  to  separate  into  sulphuric  and  hyposnlphnr- 
ous  acids,  the  latter  of  which  is  afterwards  resolved  into  sulphurous  acid 
and  free  sulphur.  Millon  {Ann,  Chim.  Fkys,  69,  89)  and  Forchhammer 
(Compt.  Rend.  4,  395),  entertain  the  less  probable  opinion  that  a  portion 
of  the  sulphur  is  combined  either  with  nitrogen  or  with  amidogen.  Du- 
mas regards  the  salt  as  NH^,  HO,  SO,  and  calls  it  Stdphimide,  But  this 
fonnula  supposes  that  the  salt  contains  one  atom  of  SO'  to  one  atom  of 
NH' — a  supposition  which  is  in  accordance  with  H.  Rose's  earlier  experi- 
ments; whereas,  according  to  his  more  recent  researches,  it  appears  to 
contain  2  atoms  of  SO^  to  1  atom  of  NH^ 

The  salt  when  exposed  to  the  air  becomes  white  and  rapidly  deliquesces; 
it  dissolves  readily  in  water.  The  solution,  which  is  yellowish  at  first,  soon 
becomes  colourless  and  acquires  a  feeble  acid  reaction.  When  kept  for  a 
long  time  in  close  vessels,  it  deposits  a  small  quantity  of  sulphur,  probably 
in  consequence  of  its  acid  being  resolved  into  sulphuric  and  hyposulphur- 
ous acid.  When  a  recently  prepared  solution  is  evaporated  in  vacuo  over 
oil  of  vitriol  at  ordinary  temperatures,  a  crystalline  residue  is  obtained 
consisting  of  a  mixture  of  ordinary  sulphate  and  hyposulphite  of  ammonia 
[for  this,  however,  the  quantity  of  ammonia  is  too  small] .  Hydrate  of 
potash  disengages  ammonia  from  the  fresh  solution,  even  at  ordinary  tem- 
peratures, and  a  larger  quantity  with  the  aid  of  heat;  and  if  the  liauid  be 
then  supersaturated  with  hydrochloric  acid,  sulphur  is  deposited,  while  sul- 
phurous and  sulphuric  acid  remain  in  solution.  Hence  the  sulphurous 
acid  must  have  combined  directly  with  the  potash  in  its  proper  form.  A 
solution  of  the  ammoniacal  salt  mixed  with  potash  and  evaporated  in 
vacuo  yields  crystals  of  sulphate  of  potash,  and  a  mother-liquor  contain- 
ing hyposulphite  of  potash.  If  a  dilute  solution  of  the  salt  is  boiled  with 
potash,  till  ammonia  ceases  to  be  evolved,  sulphurous  acid  is  obtained  on  the 
addition  of  hydrochloric  acid,  but  no  sulphur.  The  recently  prepared 
solution,  even  if  it  has  been  previously  boiled,  yields  sulphurous  acid 
without  separation  of  sulphur,  on  being  mixed  cold  with  hydrochloric  acid, 
and  the  liquid  turns  red  at  a  certain  degree  of  concentration.  But  on 
boiling  the  fresh  solution  with  hydrochloric  acid,  it  evolves  sulphurous 
acid  and  deposits  sulphur,  and  the  supernatant  liquid  is  found  to  contain 
suluhuric  acid.  A  solution  kept  for  a  long  time  out  of  contact  of  air 
yields  sulphur,  sulphurous  acid,  and  sulphuric  acid,  even  at  ordinary  tem- 


SULPHITE  OF  AMMONIA.  45  7 

peratares.  A  recently  prepared  dilate  solution  treated  with  oil  of  vitriol 
yields  nothing  but  sulphnroas  acid;  bnt  a  concentrated  solution  likewise 
gives  a  precipitate  of  sulphur.  A  recently  prepared  solution  mixed  with 
selenious  acid  at  ordinary  temperatures  gives  a  red  precipitate  of  selenium, 
just  as  common  sulphite  of  ammonia  does ;  but  a  solution  kept  for  some 
weeks  behaves  like  a  hyposulphite,  precipitating  only  a  trace  of  selenium 
containing  sulphur;  but  it  precipitates  a  larger  quantity  on  boiling,  and 
a  still  larger  quantity  on  the  addition  of  hydrochloric  acid .  The  ^eshly 
prepared  solution  yields  with  chloride  of  barium  a  precipitate  of  sulphate 
of  baryta;  and  the  filtrate,  on  the  addition  of  hydrochloric  acid,  evolves 
sulphurous  acid  and  deposits  sulphur.  In  this  case,  the  affinity  of  baryta 
for  sulphuric  acid  appears  to  be  the  cause  of  the  decomposition  of  2S0'  into 
SO^  and  SO. — The  recently  prepared  solution  does  not  affect  a  solution  of 
sulphate  of  copper  at  ordinary  temperatures;  on  the  application  of  heat,  it 
precipitates  sulphide  of  copper,  like  a  hyposulphite.  With  corrosive  sub- 
limate, it  gives  a  white  precipitate  which  is  converted  into  black  sulphide 
of  mercury  when  the  ammoniacal  salt  is  in  excess,  (just  as  with  h3rposul- 
pliite  of  ammonia;  the  ordinary  sulphite  does  not  precipitate  corrosive 
sublimate.)  With  nitrate  of  silver  also,  the  solution,  whether  new  or 
old,  behaves  like  a  h3rpo6ulphite;  when  a  small  quantity  only  of  silver 
solution  is  used,  the  white  precipitate  re-disolves ;  with  -a  larger  quantity 
it  is  permanent,  and  then  changes  through  yellow  and  brown  to  black; 
but  the  black  sulphide  of  silver  thus  obtoined  also  contains  metallic  sil- 
ver, probably  because  a  portion  of  the  sulphurous  acid  remains  unchanged 
and  acts  as  such  in  the  mixture.  (H.  Rose^  Pagg.  3d,  275;  42,  415.) 


i.    SuLPHiTB  OF  Ammonia. 

a.  Manosulphite  or  Normal  Sulphite, — Sulphurous  acid  gas  is  passed 
through  au  aqueous  solution  of  ammonia  contained  in  a  Woulfe's  appa- 
ratus; combination  takes  place  attended  with  rise  of  temperature. 
— Transparent  and  colourless  six-sided  prisms,  with  six-sided  pyramids, 
of  a  fresh,  pungent,  and  rather  sulphurous  taste. — The  salt  contains 
29-07  per  cent,  of  ammonia,  60*06  of  sulphurous  acid,  and  10*87  of  water. 
When  heated,  it  decrepitates  slightly,  becomes  soft  without  fusing, 
evolves  a  small  quantity'  of  ammonia  and  water,  and  then  sublimes  in  the 
form  of  an  cudd  mU, — When  exposed  to  the  air,  it  first  becomes  soft,  and 
then  hardens,  in  consequence  of  being  converted  into  sulphate  of  ammo- 
nia. Nitric  acid  converts  it,  with  disengagement  of  nitric  oxide  and 
sulphurous  acid  gases,  into  sulphate  and  nitrate  of  ammonia;  chlorine 
converts  it  into  snlphate  and  hydrochlorate  of  ammonia,  with  separation 
of  sulphurous  acid  gas. — The  salt  dissolves  in  one  part  of  water  at  a  tem- 
perature of  12°,  producing  a  considerable  degree  of  cold;  in  hot  water 
it  is  still  more  soluble.  The  solution  evolves  ammonia  when  boiled. 
(Fonrcroy  &  Vauquelin,  Crell.  Ann,  1800,  2,  415.) 

p.  Bisulphite, — Prepared  by  saturating  an  aqueous  solution  of  ammo- 
nia with  sulphurous  acid  gas,  or  by  subliming  the  salt  a. — But  the  mono- 
snlphite  and  the  bisulphite  when  heated  on  mercury  to  a  temperature  of 
134'',  do  not  give  off  gas,  but  are  decomposed  and  blacken  the  mercury. 
(Bineau,  Ann.  Chim,  Phys.  67,  241.) 


460  NITROGEN.    * 

When  a  solution  of  sulphate  of  ammon  is  evaporated,  it  yields  crystals 
of  parasulphate  of  ammon  and  a  mother-liquor  containing  the  deliques- 
cent salt.  It  is  not  mere  solution  that  produces  this  change;  evaporation 
seems  to  he  necessary,  Inasmuch  as  a  solution  of  sulphate  of  ammon 
exhibits  different  reactions  from  a  solution  of  parasulphate  of  ammon. 

Sulphate  of  ammon  dissolves  with  difficulty  in  hot  oil  of  vitriol,  with- 
out-evolving any  odour  of  sulphurous  acid  and  separates  again  on  cooling. 
It  is  not  soluble  in  alcohol,  and  does  not  undergo  any  change  when 
digested  with  that  liquid.  (H.  Rose.) 

2.  Acid  SulphcUe  of  Amman.  Produced  simultaneously  with  the 
neutral  sulphate  in  the  form  of  a  hard  vitreous  mass,  which  rapidly  deli- 
quesces in  the  air  and  dissolves  in  water  with  a  hissing  noise.    (H.  Rose.) 

C.  Parasulphate  of  Ammon.  Crystallizes  out  on  evaporating  a  sola- 
tion  of  sulphate  of  ammon. — 1.  The  solution  is  first  evaporated  at  a  very 
gentle  heat,  and  then  under  a  receiver  over  oil  of  vitriol ;  or  the  whole 
evaporation  is  conducted  in  vacuo  over  oil  of  vitriol,  because  the  liquid 
gradually  becomes  acid  when  heated.  The  crystals  of  parasulphate  of 
ammon  are  purified  from  the  mother-liquor  which  contains  the  deliquescent 
salt,  not  by  washing  with  water,  but  by  pressure  between  folds  of  bibulous 
paper. — 2.  After  the  neutral  sulphate  of  ammon  has  been  removed  from 
the  bottle  in  which  the  anhydrous  sulphuric  acid  was  saturated  with  am- 
moniacal  gas  ^p.  456),  the  remaining  acid  sulphate  of  ammon  is  left  for  a 
considerable  time  in  contact  with  ammoniacal  gas ;  the  residual  ammo- 
niacal  gas  is  then  completely  expelled  by  a  current  of  dry  air,  and 
the  open  bottle  left  exposed  for  a  long  time  to  moist  air;  and  lastly,  the 
mass  is  very  slowly  dissolved  in  water.  If  any  rise  of  temperature  takes 
place,  the  excess  oi  sulphuric  acid  converts  the  salt  into  ordinary  sulphate 
of  ammonia.  The  solution  is  freed  from  the  excess  of  sulphuric  acid  by 
agitation  with  carbonate  of  baryta,  filtered,  and  then  evaporated  as  in 
the  first  method.  If  the  ammoniacal  e^a  is  not  entirely  expelled  by  the 
current  of  air,  a  small  quantity  of  ordinary  sulphate  of  ammonia  is  pro- 
duced, which  cannot  be  separated  by  carbonate  of  baryta.  (H.  Rose.) 

Colourless,  transparent  crystals  belonging  to  the  square  prismatic 
system,  but  hemihedral  {Fig.  40);  of  the  8  ^-faces  belonging  to  the  primary 
form  4  are  wanting;  similarly  with  regard  to  the  8  a-faces  of  the  first 
obtuse  octohedron.  e:e=z  91°  56';  «  :  a  =  139°  28';  p  :e  =z  113°  14'; 
p:a  =  121°15';  the  jt>-face  is  square,  and  rather  uneven;  the  e  and  a  faces 
are  smooth  and  brilliant;  the  crystal  has  no  plane  of  cleavage.  ^G.  Rose.) 

Parasulphate  of  ammon  has  the  same  composition  as  sulphate  of 
ammon;  it  contains  between  70  and  70*29  per  cent,  of  sulphuric  acid. 
(H.  Rose.) 

The  ciystals  do  not  absorb  moisture  from  the  air  unless  a  portion  of 
the  deliquescent  salt  adheres  to  them.  When  moistened  with  water  and 
exposed  to  the  air,  they  are  converted,  with  separation  of  a  small  quantity 
of  sulphuric  acid,  into  the  deliquescent  salt.  They  are  rather  more 
soluble  in  water  than  sulphate  of  ammon;  the  solution  is  neutral  and 
may  be  preserved  unchanged  in  stoppered  bottles,  though  the  deliquescent 
salt  appears  to  be  gradually  formed  in  the  liquid.  When  evaporated  in 
vacuo  over  oil  of  vitriol,  it  yields  crystals  of  parasulphate  of  ammon  mixed 
with  a  small  quantity  of  the  deliquescent  salt;  but  if  evaporated  in 
the  open  air  (which  contains  carbonic  acid)  the  solution  acquires 
the  property  of  reddening  litmus  and  is  found  to  contain  a  larger 
amount  of  deliquescent  salt.     A  solution  of  the  salt  in  9  parte  of  water 


DELIQUESCENT  SULPHATE  OF  AMMON.  4(51 

givea  no  precipitate  with  tartaric  acid  after  several  days;  with  raceniic 
acid  it  yields^  after  some  time^  a  much  scantier  precipitate  than  a  solution 
of  sulphate  of  animon ;  it  behaves  like  the  latter  solution  with  sulphate 
of  alumina,  bichloride  of  platinum,  and  carbazotic  acid.  The  original 
solution  does  not  affect  the  salts  of  baryta,  strontia,  lime,  and  lead,  even 
after  a  lon^  time,  Tit  gives  a  precipitate,  however,  after  it  has  become 
acid.)  When  boiled  with  chloride  of  barium,  it  gives  a  precipitate  of 
sulphate  of  baryta,  though  the  precipitate  appears  much  more  slowly 
than  with  sulphate  of  ammon;  with  chloride  of  barium  and  hydro- 
chloric acid  together,  it  yields  a  precipitate  at  ordinary  temperatures,  but 
not  till  after  the  lapse  of  12  hours.  When  evaporated  to  dryness  with 
excess  of  chloride  of  barium  and  ignited,  the  solution  yields,  after  the 
excess  of  chloride  of  barium  has  been  dissolved  out  with  water,  a  quantity 
of  sulphate  of  baryta  which  corresponds  to  only  67*47  per  cent,  of  the 
sulphuric  acid  contained  in  the  crystals,  because  a  portion  of  the  sulphuric 
acid  volatilizes.  (H.  Rose.) 


m.    Deliquescent  Sulphate  op  Ammon. 

Remains  in  the  mother-liquor  after  the  crystallization  of  parasulphate 
of  ammon.  To  free  it  as  completely  as  possible  from  portions  of  para- 
sulphate of  ammon  retained  in  solution,  the  aqueous  solution  of  sulphate 
of  ammon  is  suffered  to  evaporate  to  perfect  diyness  in  vacuo  over  oil  of 
vitriol;  the  residue  exposed  to  the  air  till  it  undergoes  deliquescence; 
the  liquid  poured  off  from  the  crystallized  parasulphate  of  ammon ;  the 
solution  evaporated  till  parasulphate  of  ammon  crystallizes  out;  and,  after 
the  removal  of  these  crystals,  left  to  crystallize  in  vacuo.  If  the  evapo- 
ration is  conducted  in  the  open  air,  the  solution  becomes  slightly  acid, 
and  in  that  case  must  be  nentralized  by  digestion  with  carbonate  of 
baryta,  and  filtration,  previous  to  the  final  evaporation  in  vacuo. 

Ill-defined,  needle-shaped  crystals.  When  carefully  prepared,  the 
aqneous  solution  reddens  litmus  but  very  slightly. 

Calculation.  H.  Rose. 

2NH'    34  27-65 

2S0»     80  65-04  64.14 

HO     9  7-31 

NIP,SO»-f  NH^O,SO»  ...123  10000 

This  salt  may  be  regarded  as  a  compound  of  1  atom  of  sulphate  of 
ammon  with  1  atom  of  ordinary  sulphate  of  ammonia;  the  reactions  of 
the  solution,  however,  do  not  quite  accord  with  this  view  of  its  con- 
stitution. 

The  aqueous  solution  behaves  with  sulphate  of  alumina,  bichloride  of 
platinum,  tartaric  acid,  and  racemic  acid,  like  a  solution  of  sulphate  of 
ammon.  It  gives  an  immediate  cloud  with  chloride  of  barium ;  but  the  pre- 
cipitation of  the  sulphuric  acid  is  as  imperfect  as  in  the  case  of  sulphate 
of  ammon, — only  \  of  the  acid  present  being  precipitated  at  ordinary 
temperatures  in  the  course  of  24  hours;  the  addition  of  hydrochloric  acid 
causes  about  half  to  be  thrown  down.  The  solution  precipitates  a  con- 
centrated solution  of  chloride  of  strontium  immediately,  and  a  dilute  solu- 
tion after  some  time.  It  does  not  affect  a  solution  of  chloride  of  calcium. 
With  acetate  of  lead  it  behaves  in  the  same  manner  as  a  solution  of  suU 
phate  of  ammon.  (H.  Rose.) 


462  NITROGEN. 


n.    Sulphate  of  Ammonia. 

a.  MoNOSULPHATE. — Glayher*s  geheimer  Solmiokj  Sal^mmoniacum  ^e- 
cretum  Olauberi.  Occurs  Dative  aj9  Maicagnine.  Obtained  by  deoompofiing 
carbonate  or  hjdrochlorate  of  ammonia  with  salphnric  acia.  Colourkes, 
transparent,  crystals,  which,  in  their  form  and  the  magnitude  of  their 
angles,  correspond  precisely  with  those  of  sulphate  of  potash.  (Bemhardi, 
iV^.  GehLS,  413,  and  iV.  Tr.  9, 2, 25;  Beudant,  Mitscherlich,  Fogg.  18, 168.) 
Fig,  76  &  77.  y  :  y  below  121*'  8';  » :  »  =  111^  15'.  (Mitscherlich.) 
Has  a  sharp,  bitter  taste. 

Calcuhtion  a.  liitscherlich.      Ure.  Calcalfttion  t.         Berzelins.  Kirwan. 

NH»    17...  25-76  NH»  ....  17....22-67....  22-6...  14-24 

SO>     40...  60-61  SO»    ....  40    .53-33....  531....  5466 

HO  9 ...  13-63 ... 13-58  ...13  2H0        18     2400...  243  3110 

NH*b7sO»....66  ...10000  "    '  NH*O,SO»,HO75....100-00.T.T000....10000 

According  to  Berzelins,  the  crystallized  salt  contains  2  atoms  of  water, 
1  atom  of  which  is  expelled  at  a  gentle  heat ;  according  to  Mitscherlich 
{Lehrh.  2,  102),  it  contains  but  1  atom  of  water.  The  latter  statement — 
inasmuch  as  sulphato  of  ammonia  and  sulphate  of  potash  form  similar 
crystals — accords  with  the  supposition  that  KO  and  NH*0  or  NH'HO, 
and  therefore  also  NH*0,SO'  and  KO,SO*,  are  isomorphous  compounds. 

Sulphate  of  ammonia  decrepitates  when  heated,  melts  at  140°  (284'^  F.), 
and  begins  to  decompose  at  280^  (536''  F.),  whereby  the  glass  vessel  is 
corroded.  (Marchand,  Fogg.  42,  556.)  During  decomposition,  it  evolves 
ammonia,  then  water  and  nitrogen  gas,  and  disappears  entirely,  with 
sublimation  of  sulphite  of  ammonia  and  a  small  quantity  of  sulphate. 
When  passed  through  a  red-hot  tube,  it  is  resolved  into  water,  sulphur, 
and  nitrogen  gas.  (H.  Davy,  Schenve  68.)  When  heated  with  chlorate 
of  potash,  it  is  decomposed,  becoming  red-hot  and  evolving  chlorine^ 
chloric  oxide,  nitrogen,  and  a  small  quantity  of  oxygen  sas.  (Soubeiran.) 
When  evaporated  with  hydrochloric  acid,  it  is  resolved  into  sal-ammo- 
niac and  bisulphate  of  ammonia.  Becomes  somewhat  moist  on  exposure 
to  the  air;  dissolves  in  2  parts  of  cold,  and  in  1  part  of  boiling  water. 

C.  Bisulphate.  Crystallizes  in  thin  rhombohedrons  or  in  scales;  has 
an  acid  and  bitter  taste.  Deliquesces  slowly  in  the  air.  Dissolves  in 
one  part  of  cold  water.     (Link,  Grell.  Ann.  1796,  1,  25.) 

The  powder  of  »  absorbs  the  vapour  of  anhydrous  sulphuric  acid 
very  slowly  and  sparingly  at  ordinary  temperatures;  the  compound  fuses  at 
a  slightly  elevated  temperature,  and  when  strongly  heated  is  decomposed 
like  bisulphate  of  ammonia.  (H.  Rose,  Fogg,  38,  122.) 

0.      StJLPHOCARBONATE   OF   AmMONIA. 

Bisulphide  of  carbon  slowly  absorbs  ammoniacal  gas  and  is  converted 
into  a  slightly  yellow,  amorphous  powder,  which  in  the  anhydrous  state 
is  capable  of  oeing  sublimed;  it  absorbs  water  greedily,  assuming  first  an 
orange-yellow  (arising  from  hydrosulphocarbonate  of  ammonia)  and 
then  a  lemon-yellow  colour,  and  is  converted  into  ammonia,  hydrosul- 
phuric  acid,  and  carbonic  acid.  (Berzelins  &  Marcet.)  This  compound 
is  also  formed  on  heating  zanthonate  of  ammonia.  (Zeise,  Fogg.  35, 
511.) 


HTDRO-SULPHOCABBOKATE  OF  AMMONIA.  463 


p.    Hydrohsulphooabbonatb  of  Ammonia. 

The  Chamelion  Salt  (Bothwef'dendes  Salz)  of  Zeiae;  StdphocarhonaU  of 
Ammonia,  {BerzeVmB,)^ Formation  (p.  206).  10  measures  of  alcohol  satu- 
rated with  ammoniacal  gas  are  mixed  with  one  measure  of  bisulphide  of 
carbon;  the  mixture  placed  in  ice-cold  water,  as  soon  as  it  has  assumed  a 
brownish  yellow  colour;  and  the  mother-liquor,  after  standing  for  an  hour, 
poured  off  from  the  crystallized  salt  (to  prevent  the  latter  from  becoming 
contaminated  with  crystals  of  sulphocyanide  of  ammonium).  The  crystals 
are  washed  several  times  with  alcohol  and  afterwards  with  ether,  after 
which  they  are  pressed  rapidly  between  folds  of  bibulous  paper,  and 
preserved  m  a  well  stopped  bottle. 

The  salt  is  pale  yellow  and  crystalline.  When  exposed  to  the  air  it 
volatilizes  completely  in  the  course  of  a  few  days.  If  kept  from 
moisture,  it  may  be  sublimed  almost  unchanged;  a  small  quantity 
of  hydrosulphate  of  ammonia  appears,  however,  to  be  formed  during  the 
process. 

The  salt  when  moistened  with  alcohol  and  exposed  to  the  air  instantly 
assumes  a  deeper  yellow,  and  in  a  few  seconds  a  red  colour;  if  it  has  been 
well  washed  with  ether  and  carefully  pressed  dry^  it  retains  its  yellow 
colour  in  the  air  for  five  minutes,  and  in  well  closed  vessels  for  a  still 
longer  time.  The  aqueous  solution  loses  its  colour  in  the  air,  and  depo- 
sits a  grey  precipitate  containing  carbon,  but  without  formation  of  sul- 
phocyanogen.  An  aqueous  solution  of  potash  distilled  to  dryness  with 
the  salt,  gives  a  residue  of  sulphocyanide  of  potassium.  When  treated 
with  milk  of  lime,  it  yields  a  large  quantity  of  a  yellow  powder,  together 
with  a  solution  which  still  contains  hydrosulphocarbonic  acid.  Hydro- 
chloric and  sulphuric  acid  instantly  decolorize  the  red  aqueous  solution 
of  this  salt,  and  render  it  milky  by  separating  hydrosulphocarbonic 
acid  (an  excess  of  the  stronger  acids,  however,  redissolves  the  precipi- 
tate); moreover,  if  the  aqueous  solution  is  concentrated,  hydrosulphuric 
acid  is  also  evolved,  and  a  substance  resembling  sulphur  separated. 
Moderately  dilute  hydrochloric  or  sulphuric  acid  separates  pure  hydrosul- 
phocarbonic acid  from  the  dry  salt,  without  disengaging  hydrosulphuric 
acid  (p.  206).  When  left  in  closed  vessels  in  contact  with  alcohol,  the 
salt  IS  resolved  into  hydrosulphuric  acid  and  hydrosulphocyanate  of 
ammonia. 

2(NH^HCS3)  =  NH3,H*C«NS»  +  3HS. 

The  salt  attracts  moisture  from  the  air,  and  dissolves  in  water  very 
readily  and  abundantly.  One  part  of  the  salt  imparts  to  8  parts  of  water 
a  red,  to  a  larger  proportion  a  brown,  and  to  a  still  larger  quantity  a 
yellow  colour.  In  close  vessels,  the  solution  remains  unchanged  for  a 
very  long  time,  excepting  that  the  red  colour  changes  to  reddish  brown. 
It  is  sparingly  soluble  in  alcohol,  and  even  less  soluble  in  ether.  (Zeise, 
Schw.  41,  105.) 

q.      SULPHO-PHOSPHATE   OP   AmMONIA. 

Tersulphide  of  phosphorus  (prepared  with  31  '4  parts  of  phosphorus 
and  48  parts  of  sulphur)  slowly  absorbs  ammoniacal  gas;  the  absorption 
does  not  terminate  before  the  end  of  six  months.  The  compound  is  solid, 
yellowish,  and  of  hepatic  taste;  when  heated,  it  softens  without  fusing, 
and  gives  off  hydrosulphuric  acid  and  hydrosulphate  of  ammonia;  after 
which,  sulphide  of  phosphorus  sublimes,  leaving  phosphide  of  nitrogen  in 


464  NITROGEN. 

the  form  of  a  porous  mass.  The  compound  hecomes  moist  when  exposed 
to  the  air  and  gives  off  an  odour  of  ammonia  and  hjdrosulphuric  acid. 
When  treated  with  water  it  yields  phosphite  of  ammonia  and  a  com- 
pound of  sulphide  of  phosphorus  with  hjdrosulphate  of  ammonia. 
(Bineau,  Ann.  Chim.  Pkys,  70,  265.) 

Calculation.  Bineau. 

NH>    17-0  17-63  17-5 

P   31-4  32-58  32-6 

3S   48-0  49-79  49*9 


NHSPS*  96-4  100-00 100-0 

Nitrogen  and  Selenium. 

A.  MoNOHTDROSELENiATE  OF  Amhonia. — Selenide  of  Ammonium,^^ 
One  Tolume  of  seleniuretted  hydrogen  gas  mixed  with  an  excess  of  am- 
raoniacal  eas  condenses  2  volumes  of  the  latter,  forming  a  white  cloud 
which  is  deposited  in  the  form  of  a  white  mass  having  the  odour  of  sele- 
niuretted hydrogen  and  of  ammonia.  (Bineau.)  It  is  not  crystalline,  and  in 
consequence  of  the  air  removing  a  small  quantity  of  hydrogen,  it  acquires 
a  pale  red  colour,  and  forms  a  red  solution  with  water.  (Berzelius.) 

B.  Bihydroseleniate  op  Ammonia. — SeUnide  of  Ammonium  and 
Hydrogen,— -When  the  ammoniacal  gas  is  in  excess,  the  two  gases  con- 
dense in  equal  volumes  and  form  a  white  crystalline  muBB  which  smells  of 
hydroselenic  acid  and  ammonia,  and  is  less  volatile  than  bihydrosulphate  of 
ammonia.  On  exposing  it  to  heat,  selenium  is  separated.  Both  A  and 
B  are  rapidly  decomposed  in  the  air,  with  separation  of  selenium. 
(Bineau,  Ann.  Chim.  Pkys,  67,  229.) 

Calculation.  Calculation. 

A.     NH* 17  29-31  B.     NH^ 17  17-17 

HSe 41  70-69  2HSE  ....  82  8283 

NHS  HSe...  58  10030  NHS'iHSe     99  10000 

Ammoniacal  gas  and  aqueous  ammonia  have  no  effect  on  selenium. 
When  a  mixture  of  selenide  of  calcium  and  sal-ammoniac  is  distilled,  am- 
moniacal gas  and  selenium  are  evolved,  and  a  red  liquid  is  obtained  having 
a  strong  hepatic  odour,  and  producing  a  red  turbid  mixture  when  mixed 
with  a  large  quantity  of  water.  On  exposure  to  the  air,  it  is  resolved 
into  ammonia  and  water  which  escape,  and  selenium  which  is  precipitated. 
(Berzelius.)  Probably  this  liquid  should  be  regarded  as  hydroselenito  of 
ammonia,  that  is  to  say,  as  hydroselqniate  of  ammonia  containing  an  addi- 
tional quantity  of  selenium  in  solution. 

C.    Selenite  op  Ammonia. 

•  a.  Monoselenite. — Formed  by  dissolving  selenious  acid  in  a  slight  ex- 
cess of  concentrated  solutionof  ammonia,  and  leaving  the  solution  to  evapo- 
rate in  a  warm  place.  Four-sided  prisms — oblique  four-sided  tables — ^and 
feathery  crystals.  When  heated,  it  swells  considerably  and  evolves  water 
and  ammonia,  and  afterwards  water  and  nitrogen  gcus,  together  with  a  small 
quantity  of  quadroselenite  of  ammonia  partly  dissolved  in  the  water,  and 
partly  sublimed  in  the  anhydrous  state;  the  residue  consists  of  fused 
selenium.     It  deliquesces  in  the  air. 

h.  Biselenite.  Prepared  by  dissolving  the  salt  a  in  water  and  leaving 
the  solution  to  spontaneous  evaporation,  whereby  ammonia  is  evolved. 
It  forms  needles  which  are  permanent  in  the  air. 


IODIDE  OP  NITROGEN.  465 

c,  QuADRosELBNiTE.  Prepared  either  by  evaporating  a  solution  of  h 
with  the  aid  of  heat^  or  by  treating  it  with  an  aoid.  Uncrystallizable  and 
deliquescent  in  the  air.  (Berzelius.) 

Nitrogen  and  Iodine. 
Iodide  of  Nitrogen)  or  Iodide  of  Amidoobn?  Nl^or  NI  or  NH^II 

Precipitated  in  the  form  of  a  black  powder  on  mixing  iodine  or  chlo- 
ride of  iodine  with  an  aqueous  solution  of  caustic  anmionia  or  carbonate 
of  ammonia.     Either : 

4NH»  +  61  «  3(NH»,  HI)  +  NP;  or: 

4NH>  +  41  =  3(NH»,HI)  +  NI;  or: 

2NH3  +  21  =  NHS  HI  +  NH«I. 
A  small  quantity  of  nitrogen  gas  is  invariably  disengaged  during  the 
process.  A  solution  of  iodate  and  hydriodate  of  ammonia  yields  a  pre- 
cipitate of  iodide  of  nitrogen  with  potash,  only  when  hydrochloric  acid 
has  been  previously  added.  (Serullas.) — Iodide  of  nitrogen  is  also  formed 
in  the  decomposition  of  chloride  of  nitrogen  by  a  solution  of  iodide  of 
potassium. 

I.  Powdered  iodine  is  covered  with  an  excess  of  aqueous  ammonia, 
and  the  mixture  promoted  by  gentle  trituration  in  a  mortar;  the  whole  is 
then  thrown  on  a  filter  and  the  hydriodate  of  ammonia  washed  out  with 
cold  water. — 2.  Alcohol  of  33°  Joaume  is  saturated  with  iodine,  and  the 
solution,  after  filtration  or  decantation,  treated  with  a  large  excess  of  am- 
monia j  the  mixture  is  then  stirred,  diluted  with  water,  and,  after  subsi- 
<^Dg9  poured  off  from  the  iodide  of  nitrogen  produced.  The  new  com- 
pound, which  settles  at  the  bottom  of  the  vessel  in  the  form  of  a  black 
paste,  is  washed  with  cold  water  either  by  subsidence  and  decantation  or 
on  a  filter,  if  it  does  not  subside  readily.  The  iodide  of  nitrogen  thus  pro- 
duced has  the  form  of  a  very  fine  powder,  which,  as  long  as  it  re- 
mains moist,  does  not  explode  even  when  pressed  with  a  glass  rod ;  whereas 
that  which  is  prepared  oy  the  first  method  often  explodes  spontaneonsly 
even  during  washing.  But  if  the  iodine  is  precipitated  from  the 
alcoholic  solution  by  water,  and  then  ammonia  added,  spontaneously  ex- 
plosive iodide  of  nitrogen  is  obtained.  (Serullas. ) — 3.  Iodine  is  dissolved 
in  hot  aqua  regia,  and  the  solution,  which  contains  terchloride  of  iodine, 
decanted  from  the  undissolved  iodine.  On  adding  an  excess  of  ammonia 
to  the  solution,  iodide  of  nitrogen  is  precipitated  in  the  form  of  a  blackish 
brown  powder.  In  this  case,  hydrochloric  acid  and  iodide  of  nitrogen 
appear  to  be  the  only  products,  inasmuch  as  no  nitrogen  gas  is  evolved, 
and  the  liquid  contains  nothing  but  sal-ammoniac  with  the  merest  trace 
of  hydriodate  of  ammonia.  (Mitscherlich.)  Hence  it  may  be  inferred 
that  iodide  of  nitrogen  =  NI,  since : 

NH>  +  ICP  =  NI  +  3HCL 
The  compound  may  also  be  prepared  by  mixing  ammonia  with  aqueous 
solution  of  terchloride  of  iooine,  or  with  a  mixture  of  iodic  acid  and  hy- 
drochloric acid.  (Andre,  J.  Pharm.  22, 137.) 

The  iodide  of  nitrogen,  after  being  washed,  is  dried  by  exposure  to 
the  air  at  ordinary  temperatures ;  but  even  when  thus  treated,  it  of^n  ex- 
plodes spontaneously.  It  is  best  to  divide  the  filter  with  the  moist  iodide 
of  nitrogen  upon  it  into  small  pieces,  and  expose  these  to  the  air  at  con- 
siderable distances  from  each  other,  so  as  to  preclude  the  possibility  of  a 
dangerous  explosion.     In  a  receiver  full  of  ammoniacal  gas,  it  may  be 

VOL.   II.  2   H 


466  NITROGEN. 

dried  without  fear  of  explosion,  and  kept  for  six  weeka  or  more,  andeyen 
touched  without  exploding,  provided  it  has  not  preyiouslj  been  exposed 
to  the  air  a^in.  (Millon.)  Bineau  {Ann.  Chim.  Fhy».  70,  270)  also 
places  hydrate  of  potash  under  the  jar  filled  with  the  ammoniacal  gas. 
The  water  adhering  to  the  iodide  of  nitrogen  at  first  absorbs  ammoniacal 
gas;  but  after  the  iodide  of  nitrogen  has  become  perfectly  dry,  the  am- 
moniacal gas  renins  its  original  yolume ;  so  that  Uie  iodide  is  rendered 
less  explosive  without  absorbing  ammonia : 

Iodide  of  nitrogen  forms  a  brownish  black,  soft  powder. 

Caleolatien  «,  aooordiiig  to  Gay  Lnssftc.  Calculation  h. 

N   14  3-57  N   14  10 

31   378  96-43  I   126  90 


NI» 392  10000  NI  140  100 

Calculadon  e,  acoording  to  Millon.  Calculation  d,  according  to  Binean. 

/  N  14  9-86  N  14  5-23 

t2H  2  1-41  H  1  0-37 

I    126  88-73  21  252  94  40 

AdI 142  100-00  NHI« 267  100-00 

According  to  Bineau's  view,  this  substance  is  formed  from  ammonia  by 
the  substitution  of  2  atoms  of  iodine  for  2  atoms  of  hydrogen.  {N.  Ann. 
Chim.  Phy$.  15,  71.) 

Becompontiom,  Pry  iodide  of  nitrogen  explodes  from  the  slightest 
cause,  producing  a  loud  report,  and  destroying  any  solid  bodies  lyinff  near 
it.  The  explosion  is  attended  with  a  violet  light  visible  in  the  dark,  the 
nitrogen  being  set  free  in  the  form  of«  gas,  and  the  iodine  as  a  very  fine 
pow<ter.  It  explodes  when  merely  dried  in  the  air,  and  with  greater 
readiness  as  the  temperature  of  the  air  is  higher.  The  slightest  move- 
ment, or  a  ^ntle  blow,  the  least  elevation  of  temperature,  or  the  addition 
of  oil  of  vitriol  or  any  other  strong  acid,  whereby  heat  is  probably  dis- 
engaged, causes  it  to  explode.  Iodide  of  nitrogen  when  moist,  or  when 
placed  under  water,  does  not  generally  explode  unless  strongly  rubbed. 
Oils  and  other  fatty  bodies  do  not  cause  it  to  explode.  Besides  the  red 
vapour  observed  during  the  explosion,  and  consisting  of  finely  divided 
iodine,  a  white  vapour  is  also  disengaged,  probably  hydriodate  of  am- 
monia; the  light  is  occasioned  by  the  union  of  hydrogen  with  iodine: 

2(NH«1)  »  NH',  HI  +  I  +  N.  (Millon). 
If  portions  of  iodide  of  nitrosen  as  dry  as  possible  and  weighing  0-05 
grm.  each  be  repeatedly  exploded  under  the  same  glass  jar,  traces  of 
hydriodate  of  ammonia  appear  on  the  sides  of  the  vessel ;  this  seems  to 
indicate  the  presence  of  hydrogen  in  the  compound.  (Marchand,  J.  pr, 
Chem.  19, 1.) 

2.  Iodide  of  nitrogen  gradually  dissolves  under  water,  giving  off 
small  quantities  of  nitrogen,  and  forming  iodate  and  hydriodate  of  ammo- 
nia; the  solution  is  neutral  and  contains  free  iodine.  (Semllas,  Millon.) 
At  ordinary  temperatures,  the  solution  is  completed  in  a  few  days,  more 
rapidly  with  the  aid  of  heat,  and  in  a  few  minutes  if  the  water  con- 
tains sulphuric  or  nitric  acid;  but  the  iodide  of  nitrogen  prepared  by 
the  first  method — not  that  prepared  by  the  second — explodes  slightly  in 
hot  water  or  acidulated  water;  moreover,  with  the  latter  it  does  not  yield 
anjy  hvdriodic  acid.  (Serullas.)  Were  the  compound  =  NP,  an  excess  of 
acid  should  be  produced: 

NP  +  5H0  «  NH»  +  2HI  +  I0»; 


IODIDE  OF  NITROGEN.  467 

^  the  deeomposition  may,  however,  be   e:iCplauied  aooording  to  calenla- 

lit  tion  c; 

,  3(NH«I)  +  5H0  =.  2(NH3,  HI)  +  NH»,  I0»  (MiUon); 

and  alflo  aooording  to  oalcolation  b : 

SNI  +  lOHO  =  NH»,  HI  +  2  (NH»IO»). 
Bat  inasmuch  as  indefinite  quantities  of  nitrogen  and  Iodine  are  set  free 

^  during  the  decomposition^  and  the  proportion  of  the  iodate  of  ammonia  to 

the  hjdriodio  acia  has  not  been  ascertained,  no  decided  oonclasion  can  be 
arrived  at  When  dilute  hydrochloric  acid  is  gradually  added  to  iodide  of 
nitrogen  under  water,  the  iodide  dissolves  completely  without  evolution  of 
1^,  and  the  solution  contains  ammonia  in  combination  with  hydrochloric, 
nydriodio,  and  iodic  acids.  If  caustic  potash  or  carbonate  of  potash  be  then 
added  in  very  slii'ht  excess,  iodide  of  nitro^n  again  separates,  because  the 
ammonia  set  free  by  the  potash  reproduces  iodide  of  nitrogen  with  the  two 
acids  of  iodine  present;  the  iodide  of  nitrogen  in  this  manner  may  be  re- 
peatedly dissolved  in  hydrochloric  acid  and  precipitated  by  potash. 
(Serullas.)  Nevertheless,  it  diminishes  after  each  precipitation,  in  con- 
sequence of  nitrogen  gas  being  evolved  and  iodine  separated.  (Millon.) 
If  6  drops  of  strong  hydrochloric  acid  are  poured  upon  2  grammes  of  well 
washed  iodide  of  nitrogen,  the  resulting  liquid  has  no  acid  reaction,  all  the 
three  acids,  namely,  hydrochloric,  hydriodic  and  iodic  acid,  being  saturated 
with  ammonia.  (Millon.) 

8.  Iodide  of  nitrogen  is  almost  instantly  decomposed  by  sulphuretted 
hydrogen  water,  with  separation  of  sulphur,  but  no  disengagement  of 
gas;  the  resulting  solution  contains  hydnodate  of  ammonia  with  a  slight 
excess  of  hydriodic  acid,  derived  from  free  iodine  mixed  with  the  iodide 
of  nitrogen.  (Serullas). — According  to  calculation  a,  a  very  acid  liquid 
should  be  obtained : 

NI3  +  6HS  =  NH»,  SHI  +  6Sj 
but,  according  to  calculation  5  or  c,  a  neutral  solution  should  be  formed : 

NI  +  4HS  =  NH»,  HI  +  4Sj  and 
NHM  +  2HS  =  NH»,HI  +  2S. 

4.  Solution  of  potash  or  milk  of  lime  slowly  added  to  iodide  of  nitro- 
gen under  water,  dissolves  it  with  evolution  of  ammonia,  and  formation 
of  iodate  of  potash  [and  iodide  of  potassium)].  A  mere  trace  of  nitrogen 
is  evolved  at  the  samo  time — ^more,  however,  if  the  solution  of  potash  is 
concentrated,  because  a  rise  of  temperature  then  takes  place.  (Serullas.) 

Aooording  to  a:  NK  +  3KO  +  3HO  =  2KI  +  K0,10«  +  NH*; 
Acoordiiigto  bi  3NI  +  3KO  +  9HO  »  KI  +  2(KO,  I0«)  +  3NH>; 
According  to  c:  3NHM  +  3KO  +  3H0  =  2KI  +  2K0,I0»  +  3NH». 


B.    a.  Iodide  of  Ammonia  1 

Dry  iodine  abciorbs  dry  ammoniacal  gas:  100  parts  of  iodine  take  up 
8-3  parts  at  -h  lO**;  9  parts  at  0*»;  and  94  parts  at  -18°;  at  0°  and 
above,  but  not  at  - 18**,  a  small  quantity  of  nitrogen  gas  is  set  free,  in 
consequence  of  the  rise  of  temperature  produced  by  the  absorption.  (Mil- 
lon).— 100  parts  of  iodine  absorb  20-55  parts  of  ammonia.  (Bineau,  Ann, 
Chim,  Phys,  67,  226.}  Combination  is  also  effected  by  gently  heating 
iodine  with  sesquicarbonate  of  ammonia»  water  and  carbonic  acid  being 
disengaged.  (Colin,  Bineau.) 

2  B  21 


468  NITROGEN. 

Blackifih-brown,  reiy  tenacious  liquid,  haviuga  metallie  aspect;  the' 
lustre  and  tenacity  are  destroyed  by  excess  of  ammonia.  When  heated, 
it  evolves  a  portion  of  ammonia,  and  then  sublimes  undecomposed  in 
violet-coloured  rapours.  (Gay-Lussac.)— The  compound  smells  of  iodine 
and  ammonia,  and  imparts  a  brown  stain  to  the  skin  and  to  paper.  A 
large  quantity  of  ammonia  renders  it  as  fluid  as  water,  but  on  expoenre 
to  the  air,  it  again  becomes  thick.  (Landgrebe,  Sckw,  52,  100.) 

Calcnlatioii,  aooording  to  MiUon.  Calculation,  according  to  Bineao. 

NH»    17  11-89  3NH»  51  1802 

1 126  8811  21 232  81-28 

NH'I 143  10000  3NHM*....  283  100  00 

According  to  Millon,  it  is  a  compound  of  one  atom  of  iodide  of 
amidogen,  (the  so-called  iodide  of  nitrogen,)  with  one  atom  of  hydriodate 
of  ammonia; 

2{NHM)  =  NH«,I  +  NH%H1. 

This  view  is  supported  by  the  following  statement  of  Millon,  viz. :  that 
from  a  small  quantity  of  iodide  of  ammonia,  a  large  quantity,  having  the 
same  properties,  may  be  prepared,  by  adding  to  the  iodide  of  ammonia, 
first  a  small  quantity  of  iodide  of  amidogen,  which  shortly  dissolves, 
then  powdered  hydriodate  of  ammonia,  which  accelerates  the  solution, 
then  iodide  of  amidogen  again,  and  so  on. 

Water  converts  iodide  of  ammonia  into  aqueous  hydriodate  of  am- 
monia and  insoluble  iodide  of  nitrogen.  (Gay-Lussac.)  A  current  of 
hydrochloric  acid  gas  converts  it  into  nitrogen  gas,  sal-ammoniac,  hydrio- 
date of  ammonia,  and  free  iodine.  (Millon.)  Iodide  of  ammonia  dissolves 
readily  in  alcohol. 

h.    Hydriodate  of  Ammonia. 

Iodide  of  Ammonium, — The  two  gases  condense  in  equal  volumes.^-^ 
Caustic  ammonia  or  carbonate  of  ammonia,  is  saturated  with  an  aqueous 
solution  of  hydriodic  acid ;  or  a  solution  of  iodide  of  iron  is  precipitated 
by  carbonate  of  ammonia,  and  the  liquid  filtered. — The  solution  obtained 
in  the  preparation  of  iodide  of  nitrogen  also  contains  this  salt.  — It  appears 
to  crystallize  in  cubes,  and  is  colourless. — It  volatilizes  undecomposed 
out  of  contact  of  air,  but  when  air  is  present,  it  yields  a  sublimate 
coloured  yellow  from  excess  of  iodine. — At  ordinary  temperatures,  it 
absorbs  the  vapour  of  anhydrous  sulphuric  acid  and  is  decomposed, 
giving  off  sulphurous  acid  and  forming  a  reddish-brown  mass.  (H. 
Rose). — Extremely  deliquescent;  easily  soluble  in  water  and  alcohol. 
The  solution  acouires  a  yellow  colour  in  the  air,  the  salt  being  partially 
converted  into  the  following  compound,  from  oxidation  of  hydrogen  in 
the  hydriodic  acid,  and  volatilization  of  ammonia. 

Calculation.  Volume. 

NH» 17  11-81  Ammoniacal  gas 1 

HI 127  88-19 Hydriodic  add  gas 1 

NH»HI....  144  10000 

c.    Htdriodite  of  Ammonia. 

Periodide  of  Ammonium. — An  aqueous  solution  of  iodide  of  ammo- 
nium saturated  with  iodine,  forms  a  dark  brown,  nearly  opaque  liquid. 


NITROGEN  AND  BROMINE.  469 

d.    loDATB  OF  Ammonia. 

An  aqneons  solation  of  iodic  acid  or  terchloride  of  iodine  is  nen< 
tralized  with  caustic  ammonia  or  carbonate  of  ammonia.  The  salt 
separates  in  the  form  of  a  sparingly  soluble  ciystalline  powder.  By 
slowly  evaporating  the  solution,  it  may  be  obtained  in  yery  brilliant 
colourless  cubes. — The  crystals  do  not  lose  weight  when  slightly  heated, 
but  at  ]  50°,  they  are  decomposed  with  a  hissing  noise,  evolying  a  mixture 
of  oxygen  and  nitrogen  gases  in  equal  volumes,  together  with  vapour 
of  iodine  and  water.  (Rammelsberg.) 

NH»,  HO,  10*  =  4HO  +  I  +  N  +  20. 
— When  thrown  on  ignited  charcoal  it  explodes  violently,  with  evolution 
of  violet-coloured  vapours.  (Vauquelin.)  With  hydrochloric  acid,  it  yields 
water,  free  chlorine,  and  a  compound  of  sal-ammoniac  with  terchloride 
of  iodine.  (Filhol.)  Dissolves  in  38*5  parts  of  water  at  15°,  and  in  6*9 
parts  of  boiling  water.  (Rammelsberg,  I^ogg.  44,  555,) 

CalcnlatioD.  RammelsberK. 

NH» 17  8-86 

I0»  166  86-46  15-987 

HO  9  4-68 

Crygtallized   192  100*00 

Nitrogen  and  Bromine. 

A.  Bromide  of  Nitrogen?  or  Bromide  of  Amidogen? — An  aque- 
ous solution  of  bromide  of  potassium  is  added  drop  by  drop  to  chloride  of 
nitrogen  covered  with  a  thin  stratum  of  water.  The  yellow  colour  of 
the  chloride  of  nitrogen  changes,  on  the  addition  of  the  bromide,  into  a 
red,  which  continues  to  increase  in  depth. — Dense,  blackish-red,  very 
volatile  oil,  the  vapour  of  which  has  an  offensive  odour,  and  attacks  the 
eyes  very  strongly. — Explodes  violently  by  contact  with  phosphorus  and 
fLrsenic.<-^When  kept  under  water,  it  becomes  covered  with  a  bubble  of 
nitrogen  gas,  which  increases,  bursts,  and  is  again  formed,  till  the  com* 
pound  entirely  disappears;  the  water  at  the  same  time  dissolves  hydro« 
bromate  of  ammonia,  with  excess  of  bromine.  Aqueous  solution  of 
ammonia  decomposes  the  oil,  producing  dense  white  fumes.  (Millon,  Ann, 
Chim.  PhyB,  69,  75.) 

B.  Hydrobromate  of  Ammonia. — Bromide  of  Ammonium, — The 
two  gases  condense  in  equal  volumes.  Aqueous  solution  of  ammonia  is 
saturated  with  hydrobromic  acid  and  the  liquid  evaporated. — Long, 
colourless  crystals,  having  a  sharp,  saline  taste ;  when  heated,  they  evapo- 
rate without  previously  fusing. — When  exposed  to  the  air,  this  compound 
becomes  slightly  yellow,  and  acid  to  litmus  paper,  from  formation  of  a 
small  quantity  of  hydrobromite  of  ammonia.  (Balard.)  It  dissolves 
readily  in  water,  very  sparingly  in  alcohol. 

Calculation.  Volame. 

NH»  17-0  17-63  Ammoniacal  gas 1 

HBr    79-4  82-37  Hydrobromic  acid  gas 1 

NH»,HBr.    96-4  lOO'OO 

C.  Bromate  of  Ammonia. — Formed  by  saturating  aqueous  solution 
of  ammonia  with  aqueous  bromic  acid,  or  by  precipitating  bromate  of 
baryta  by  carbonate  of  ammonia,  and  filtering  the  solution.     Colourless 


470  NITROGEN. 

needles  and  grains  of  a  very  pungent  and  cooling  taste.  (Lowbig.)  Ex- 
plodes yiolentlj,  not  only  when  gently  heated^  but  even  at  ordinary 
temperatures,  after  a  short  time,  so  that  it  cannot  be  kept  in  the  solid 
state.  The  products  of  decomposition  are  water,  bromine  vapour^  nitro- 
gen, and  oxygen.  (Rammelsberg,  Pogg.  52,  85.) 

D.  Amuonio-Tebbrouidb  of  Phosphobus. — Terbromide  of  phos- 
pborus  absorbs  ammoniacal  gas,  with  great  disengagement  of  heat!  If, 
however,  the  rise  of  temperature  be  prevented  by  surrounding  the  bromide 
of  phosphorus  with  a  freezing  mixture  and  passing  the  ammoniacal  gas 
very  slowly  into  it,  a  white  powder  is  obtamed,  which,  when  ignited  in 
a  current  of  carbonic  acid  gas,  is  resolved  into  between  13*24  and  18*81 
per  cent,  of  phosphide  of  nitrogen,  together  with  hydrobromate  of 
ammonia,  vapour  of  phosphorus,  ammoniacal  gas,  and  nydrogen.  The 
compound  dissolves  slowly  but  completely  in  water,  yielding  a  solution 
of  phosphite  and  hydrobromate  of  ammonia. 

5NH»,PBr»  +  3H0  =  2NH»,PO>  +  3(NH»,  HBr.) 
(H,  Rose,  Pogg.  28,  549.) 

Calcalatioii.  H,  Rofle. 

5NH»  850  2417 

P    31-4  8-93 

3Br  235-2  66'90  66'» 

5NH»,  3PBr»  351-6  100-00 

NiTROOBN  AND  CHLORINE. 

A.    a.  Chloriob  of  Nitrogen  f  or  Chloride  op  Amidoobn  f 

Chhr-SHckstojf,  BcUogenazot,  Ghlorure  cTatote. — The  composition  of 
this  explosive  oil  is  involved  in  as  much  uncertainty  as  that  of  iodide  or 
bromide  of  nitrogen;  it  is,  however,  analogous  to  these  compounds,  inas- 
much as  it  yields  iodide  of  nitrogen  and  chloride  of  potassium  with  an 
aqueous  solution  of  iodide  of  potassium,  and  bromide  of  nitrogen  and  chlo- 
ride of  potassium  with  bromide  of  potassium.  As  in  the  case  of  iodide  of 
nitrogen,  a  may  represent  the  assumption  that  chloride  of  nitrogen  is 
NCP;  6,  that  it  is  NCI,  and  c,  that  it  is  NH^  CI. 

Formalwn, — 1.  When  chlorine  is  made  to  act  on  free  ammonia  or  a 
compound  of  ammonia  with  a  weak  acid  dissolved  in  water,  sal-ammoniac 
is  formed  and  all  the  nitrogen  is  set  free  (p.  423), — or  if  any  chloride  of 
nitroffen  be  formed,  it  is  rapidly  decomposed;  but  if  the  ammonia  is 
combmed  with  a  stronger  acid,  as  phosphoric,  sulphuric,  hydrochloric, 
nitric,  or  oxalic  acid,  which  in  some  measure  protect  the  ammonia  from 
the  decomposing  influence  of  the  chlorine,  the  latter  not  only  unites  with 
the  hydrogen  of  the  ammonia,  whereby  free  hydrochloric  acid  is  formed, 
but  a  portion  of  it  combines  at  the  same  time  with  the  nascent  nitrogen 
(or  with  the  amidogen),  and  produces  the  explosive  oil.  According  to 
theory  a,  the  sal-ammoniac  is  decomposed  in  the  following  manner : 

NHSHCl  +  6C1  =  4HCI  +  NQs;  (Seh.  38); 
according  to  theory  b  : 

NHS  HCl  +  401  a  4Ha  4  NCI| 
according  to  theory  c  : 

NH>yHCl  +  2C1  «  2HCI  +  NH«,C1. 


CHLORIDE  OF  NITROGEN.  47 1 

The  formation  of  the  oil  is  not  attended  hj  any  sensible  rise  of  tempera- 
ture. (Dulong.)  It  is  effected  more  rapidfj  at  +  32^  C.  and  above,  than 
at  ordmary  temperatures;  below  0°  it  does  not  take  place  at  all;  it  is 
also  prevented  when  the  solution  of  the  ammoniacal  salt  contains  hydro- 
sulphite  of  ammonia  (NH^  HS*),  or  when  it  is  mixed  with  powdered 
sulphur  or  powdered  charcoal,  or  when  the  chlorine  ffas  is  mixed  with  a 
third  of  its  volume  of  air  or  carbonic  acid  gas,  or  with  an  equal  volume 
of  hydrogen  gas.  (Porret,  Wilson,  &  Kirk.) — 2.  An  aaueous  solution  of 
hypochlorous  acid  produces  the  explosive  oil,  both  witn  solutions  of  the 
ammoniacal  salts  and  with  free  ammonia.  (Balard.) 

Preparation, — 1.  Chlorine  gas  is  passed  through  the  solution  of  a 
suitable  ammoniacal  salt  at  a  temperature  of  -h  8^  (46*4^  F. ).  (Dulong.) 
Berzelius  fills  a  glass  jar  with  solution  of  sal-ammoniac,  inverts  it  in  a 
dish  filled  with  the  same  solution,  and  passes  chlorine  gas  into  the  jar. — 
2.  A  bottle  of  the  capacity  of  16  cubic  inches  is  filled  with  chlorine  gas 
over  hot  water  and  inverted  in  a  dish  containing  solution  of  sal-ammoniac  at 
a  temperature  of  32°  C.  (89-6''  F.)  (Porret,  WUson,  &  Kirk.)  The  oil  pro- 
duced first  saturates  the  chlorine  with  its  vapour,  then  forms  a  film  on 
the  sides  of  the  vessel  and  over  the  liquid,  and  finally  sinks  to  the  bottom 
in  the  form  of  drops.  Serullas  inverts  the  jar  filled  with  chlorine  gas 
over  a  dish  containing  a  lukewarm  solution  of  one  part  of  sal-ammoniao 
in  15  parts  of  water;  pours  more  solution  into  the  dish  in  proportion  as  it 
rises  in  the  jar;  and  when  the  chlorine  has  entirely  disappeared,  cau- 
tiously removes  the  jar,  so  as  to  prevent  the  oil  from  attaching  itself  to 
the  surface,  and  thereby  forming  a  film  which  would  rapidly  volatilize  in 
the  air.  He  then  inclines  the  dish  containing  the  oil  and  passes  a  conti- 
nuous stream  of  lukewarm  water  over  it,  in  such  a  manner  that  the  oil 
ma^  be  constantly  covered  with  water;  this  is  continued  till  the  water 
which  runs  off  no  longer  forms  a  cloud  with  solution  of  silver. — 3.  A  piece 
of  sal-ammoniao  or  of  sulphate  of  ammonia  is  suspended  in  an  aqueous 
solution  of  hypochlorous  acid;  the  oily  drops  are  deposited,  and  small 
quantities  of  nitrogen  and  chlorine  are  evolved.  (Balard.) 

The  preparation  and  handling  of  this  body  require  the  greatest  eau- 
tion.  The  glass  jar  must  be  fre^  from  every  trace  of  h,t  by  treatment 
with  potash  and  water,  as  even  the  grease  from  the  fingers  may  cause 
an  explosion.  Explosion  often  takes  place  spontaneously^  without  any 
apparent  cause.  In  all  experiments  with  this  substance^  thick  gloves 
and  a  strong  mask  with  thick  pieces  of  glass  before  the  eyes  are  indis- 
pensable. It  is  preserved  in  sealed  glass  tubes,  with  some  watery  liquid 
placed  above  it. 

Propertie$,  Thin  oil  of  the  colour  of  wax,  and  of  specific  g»^i^ 
1-653;  does  not  freeze  at  a  temperature  near— 40**.  (H.  Davy.)  Volatil- 
izes rapidly  in  the  air.  May  be  distilled  at  a  temperature  below  +  ri"* 
il60*  F.).  Does  not  appear  to  conduct  electricity.  ^Porret,  Wilson,  & 
Cirk.)  Has  a  peculiar  pungent  odour,  and  makes  me  eyes  smart;  its 
action  on  the  lungs  is  less  powerful  than  that  of  chlorine. 

Calculatioii  a.  Binean. 

K  14     11-65  10-6 

Sa    ....  106-2  88-35  69-3 

NC1»  ....  120-2  10000  1000 


472  NITROGEN. 

CdcaUtion  h.  Calculation  e. 

N      14     28-34  NH« 16     3113 

CI     35  4  71-66 g 35-4  6887 

NCI 49-4  10000  NH*,C1....  61-4  10000 

According  to  Sir  H.  Davy,  it  ia  NCI*;  according  to  Porret,  Wilson,  & 
Kirk,  NHCP;  according  to  Millon  {Ann.  Chim,  Fhys.  69,  75),  it  is  a 
componnd  of  nitride  of  chlorine  with  ammonia,  CPN-f  2H'N.  Bineaa 
regarrls  it  as  ammonia,  the  hydrogen  of  which  is  wholly  replaced  by  chlo- 
rine (iT,  Ann.  Chim.  Phy$.  15,  71). 

DecompasUians.  Many  circumstances  cause  chloride  of  nitrogen  to 
explode  with  great  yiolence,  producing  a  flashing  light  and  loud  report, 
and  often  shattering  the  containing  vessel  in  pieces.  A  grain  and  a  half 
of  the  oil  produces  a  report  louder  than  the  discharge  of  a  gun. — The 
explosion  is  induced  either  by  direct  elevation  of  temperature  to  at  least 
93''  (about  200""  F.),  as  when  a  red-hot  iron  is  brought  in  contact  with  the 
vapour,  &c.,  or  by  touching  the  liquid  with  substances  which  unite  with 
a  portion  of  the  chlorine,  the  combination  being  attended  with  rise  of 
temperature.  An  extremely  violent  explosion  is  caused  by  phosphorus ; 
and  also,  according  to  SeruUas,  by  selenium  or  arsenic  in  the  form  of 
powder ;  somewhat  less  powerful  explosions  are  produced  by  phosphide 
of  calcium,  phosphorus  dissolved  in  bisulphide  of  carbon,  phosphuretted 
hydrogen  gas  (which  at  the  same  time  disappears)  sulphuretted  hydro- 
gen gas,  persulphide  of  hydrogen,  nitric  oxide  gas,  strong  aqueous 
ammonia;  lead-paint,  manganese,  the  compounds  (soaps)  of  maigaric 
and  oleic  acid  with  the  oxides  of  manganese,  copper,  silver,  and  mercury; 
rock  oil,  the  oils  of  amber,  turpentine,  and  orange,  phosphuretted  cam- 
phor, palm-oil,  train-oil,  olive-oil,  camphorated  olive-oil,  linseed-oil,  amber, 
myrrh,  caoutchouc. — Hydrate  of  potash  likewise  causes  explosion  when 
water  is  present,  in  consequence  of  the  heat  disengaged  when  it  dissolves. 
(Porret,  Wilson  &  Kirk.)  Cyanide  of  potassium  also  causes  explosion, 
whether  in  the  solid  state  or  in  the  form  of  a  concentrated  solution. 
(Millon.) 

2.  The  following  substances  effect  a  gradual  decomposition  of  chloride 
pf  nitrogen,  generally  accompanied  by  effervescence  and  the  disengagement 
of  nitrogen  gas,  sometimes  also  of  chlorine  gas. 

When  kept  under  cold  water,  chloride  of  nitrogen  disappears  in  the 
course  of  24  hours,  nitrogen  and  chlorine  gases  being  evolved  and  hy- 
drochloric and  nitric  acid  lormed.  (H,  Davy,  SeruUas.) 

Sulphuretted  hydrogen  water  deposits  milk  of  sulphur,  with  slight 
evolution  of  nitrogen  gas,  and  gives  a  solution  of  sal-ammoniac,  in 
which  the  hydrochloric  acid  is  slightly  in  excess,  in  consequence  of  the 
separation  of  nitrogen  which  has  taken  place.  (SeruUas.)  [The  fact  of 
the  solution  being  nearly  neutral  can  be  explained  only  by  the  theory  6, 
or  c;  according  to  the  theory  a,  3  atoms  of  hydrochloric  acid  should  be 
formed  to  1  atom  of  ammonia.] 

Concentrated  hydrochloric  acid  gradually  converts  the  oil  into 
hydrochlorate  of  ammonia,  disengaging  a  quantity  of  chlorine  gas, 
greater  than  the  original  weight  of  the  oil;  1  grain  evolves  at  most  3*9 
cubic  inches  of  chlorine  gas;  a  portion  of  chlorine  likewise  remains 
dissolved  in  the  hydrochloric  acid.  (H.  Davy.)  [An  instance  of  reci- 
procal affinity;  since  chlorine  and  sal-ammoniac  form  hydrochloric  acid 
and  the  explosive  oil,  and  the  latter  is  again  resolved  by  concentrated 


CHLORIDE  OF  NITROGEN.  473 

hydrochlorio  aoid  into  sal-ammoniac  and  chlorine.]  According  to  a : 
NCP+4HC1  =  NH*C1  +  6C1;— according  to  6:  NC1  +  4HC1  =  NH*Cl 
+  4C1;— according  to  c:  NH»C1-|-2HC1  =  NH*C1+2C1. 

Under  dilute  sulpharic  acid,  the  oil  disappears,  with  evolation  of 
nitrogen  and  oxygen  gases ;  under  concentrated  nitric  acid,  with  evolution 
of  nitrocen  gas.  (Sir  H.  Davy.) 

With  dilute  ammonia,  it  evolves  nitrogen  gas  and  forms  nitric  acid. 
(H.  Davy.) 

Dilute  solution  of  potash  gives  rise  to  the  formation  of  hydrochlorate 
and  nitrate  of  potash,  with  evolution  of  nitrogen  gas.  The  oxides  of  lead, 
cohalt,  copper,  and  silver  likewise  disengage  nitrogen  gas,  and  form  chlo- 
rides and  nitrates.  (Serullas.) 

Copper  or  mercury  placed  in  contact  with  the  oil  under  water,  disen- 
gages nitrogen  gas  and  yields  a  metallic  dichloride  and  protochloride  of 
the  metal.  (Dulong,  H.  Davy.)  When  chloride  of  nitrogen  is  passed 
np  an  inverted  tube  filled  with  mercury,  2  grains  are  sufficient  to  cause 
explosion ;  but  a  smaller  quantity  is  quietly  decomposed,  a  mixture  of 
dichloride  and  protochloride  of  mercury  bemg  formed,  and  nitrogen  gas 
evolved,  amounting  in  quantity  to  9  per  cent,  of  the  chloride  of  nitrogen 
employed.  (H.  Davy.) 

A  solution  of  nitrate  of  silver  sometimes  disengages  nearly  2  measures 
of  chlorine  to  1  of  nitrogen,  chloride  of  silver  being  precipitated,  and 
nitric  acid  formed  at  the  same  time.  (Serullas.) 

Arsenious  acid  rapidly  produces  ammonia,  and  causes  partial  volatiliza- 
tion of  the  oil.  (Serullas.) — The  oil  separates  arsenic  from  arseniuretted 
hydrogen.  (Porret,  &c.) 

An  aqueous  solution  of  monosulphide  of  potassium  produces  a  greenish- 
coloured  powder,  which  floats  on  the  surface  of  the  liquid. — An  aqueous 
solution  of  bromide  or  iodide  of  potassium  converts  chloride  of  amidogen 
into  bromide  or  iodide  of  amidogen  and  chloride  of  potassium.  (Millon.^ 

A  moderately-concentrated  solution  of  cyanide  of  potassium  yields 
with  chloride  of  amidogen — chloride  of  potassium  and  a  white  cloud  pro- 
bably consisting  of  cyanide  of  amidogen;  a  dilute  solution  disengages 
nitrogen  gas  only. — Sulpho-cyanide  of  potassium,  either  in  the  solid  or 
liquid  state,  produces  an  orange-coloured  buttery  mass,  which  dissolves 
in  excess  of  the  sulpho-cyanide.  (Millon.) 

The  following  substances  also  give  rise  to  the  gradual  decomposition 
of  chloride  of  nitrogen,  with  slight  effervescence:  lime,  carbonate  of  lime, 
red-lead ;  the  soaps  formed  by  the  combination  of  baryta,  strontia,  lime, 
and  magnesia,  with  margaric  and  oleic  acid ;  common  resin,  ox-gall  resin ; 
— and  with  rapid  effervescence,  the  soaps  formed  with  potash,  alumina, 
tin,  and  cobalt;  and  the  solutions  of  phoerohoms  in  ether,  and  of  resin  or 
shellac  in  alcohol.  (Porret,  Wilson  &  Kirk.) 

The  following  substances  exert  no  decomposing  action  on  chloride  of 
nitrogen  :  sulphur,  bi-sulphide  of  carbon ;  dilute  phosphoric,  sulphuric, 
hydrochloric,  and  nitric  acids;  ferro-cyanide  of  potassium;  tin,  zinc,  native 
sulphide  of  antimony,  cinnabar,  charcoal,  jet;  shellac,  frankincense,  scam- 
mony,  aloes,  gum-ammoniac,  wax,  spermaceti,  stearine,  butter,  lard,  alco- 
hol, sulphuric  ether,  nitrous  ether,  sugar,  manna,  gum,  starch,  indigo, 
gum-kino,  catechu,  dried  white  of  ^gg,  and  benzoic  acid.—- Chloride  of 
nitrogen  may  likewise,  to  all  appearances,  be  evaporated  in  oxygen, 
hydrogen,  nitrogen,  defiant  gas,  and  atmospheric  air,  without  being 
decomposed.  (Porret,  Wilson  &  Kirk.) 


474  KmtOGSN. 

OmUnat%&ni.—a»  Solpkur,  when  Added  in  small  poriionB  to  the  oU^ 
is  quietly  diasolyed.  (BenillaB.)  Aooording  to  Dolong,  sulphur  deooiii<- 
poses  chloride  of  nitrogen,  producing  a  oompound  which  rapidly  dissolves 
in  water,  and  forms  a  solution  of  hydrochloric  and  sulphuric  acids. 

6.  With  hisulphide  of  carhon,  chloride  of  nitrogen  forms  a  jelloir 
mixture  which  does  not  explode  with  phosphorus  or  &tty  oils,  hut  quietly 
sets  fire  to  an  excess  of  these  substances.  (Porret,  Sio.)  A  mixture  of  chlo- 
ride of  nitrogen  and  bisulphide  of  carbon,  is  slowly  decomposed  under  wa- 
ter, into  nitrogen  gas,  ammonia^  hydrochloric  acid,  and  sulphuric  acid;  the 
addition  of  phosphorus  to  the  mixture  causes  violent  ebullition.  (SemUas.) 

€,  The  oil  dissolves  in  terchloride  of  phosphorus  and  in  chloride  of 
sulphur.  (H.  Davy.) 

d»  With  numerous  organic  substances:  the  combination  is,  howerer,  in 
most  instances  attended  with  effervescence,  and  coDsequently  with  partial 
if  not  total  decomposition.  Thus  it  combines  with  asphalt,  efaterite,  oopal, 
mastic,  guiacum,  enphorbium,  asafcatida,  camphor,  sulphuretted  camphor, 
oil  of  musk,  stearic  and  oleic  acids,  olive-oil^  palm-oil  and  oil  of  turpen- 
tine, when  chlorine  is  made  to  pass  through  them,  and  with  olive  oil  which 
hu  been  boiled  over  corrosive  sublimate.  (Porret^  Wilson  &  Kirk.) 


h.   CHLOROPHOS^HlDfi  OF  NiTROOEN.      N*P*C1*. 

Formed  by  the  action  of  pentachloride  of  phosphorus  on  ammonia  or 
sal-ammoniac.— I.  Pentachloride  of  phosphorus  is  saturated  with  moist 
ammoniacal  gas,  and  the  white  mass  produced  is  distilled  with  water. 
The  crystals  which  condense  in  the  water  contained  in  the  receiver  are 
then  collected  on  a  filter,  washed,  dried,  and  purified  by  solution  in  hot 
ether  and  re -crystallization. — 2.  Pentachloride  of  phosphorus  is  placed  at 
the  closed  end  of  a  glass  tube  3  feet  in  length,  and  at  a  short  distance 
from  it,  long  pieces  of  sal-ammoniac  are  introduced,  in  such  quantity  that 
the  tube  may  he  half  filled  with  them.  The  tube  is  then  laid  horizon- 
tally in  a  long  furnace,  similar  to  that  used  for  organic  analysis,  and  the 
sal-ammoniac  first  heated  till  it  begins  to  volatilize ;  a  gentle  heat  is  then 
applied  to  the  chloride  of  phosphorus,  so  that  its  vapour  may  slowly  pass 
over  the  sal-ammoniac,  and  be  completely  decomposed.  A  larffe  quantity 
of  hydrochloric  acid  gas  is  evolved,  and  the  cool  part  of  the  tube  becomes 
filled  with  crystals  of  chlorophosphide  of  nitrogen.  This  portion  of  the 
tube  is  broken  oflf,  and  freed  from  sal-ammoniac  by  slightly  washing  it 
with  water.     The  new  compound  is  finally  purified  with  ether. 

Large,  colourless,  transparent,  regular,  six-sided  prisms,  brittle,  easily 
pulverized;  not  moistened  by  water,  like  grease;  fuse  below  100°,  and 
form  a  transparent  colourless  liquid,  which  at  a  higher  temperature  boils 
and  sublimes  unchanged;  when  slightly  heated,  it  exhales  a  peculiar  but 
not  pungent  odour. 

Calcalfttion.  WShler  &  liebig. 

2N     28-0  9-3«  10-3 

3P 94-2  31-49  31-4 

5C1    1770  5915  583 

N«PCl»....  299-2  lOO^ob  1000 

When  ignited  with  oxide  of  copper  in  a  tube,  this  compound  yields 
nitrogen  cas  and  hyponitric  acid.  When  its  vapour  is  passed  over  red- 
hot  iron,  uie  products  are  nitrogen  gas  free  from  hydrogen,  and  a  crystal- 
line nuws  from  which  w^ter  extracts  chloride  of  iron^  and  leaves  olack 


>-  CHLOROSULPHIDE  OF  NITROGEN.  475 

■|  pttlreralent  phosphide  of  iron.     Alcohol  and  ether  disaolre  the  oompoand 

^  with  fiusility.     Sulphuric,  hydrochloric,  and  nitric  acids  and  solution  of 

*^  potash  neittier  decompose  nor  dissolve  it;  but  on  the  application  of  heat, 

it  swims  on  their  surface  in  oily  drops  and  sublimes.  (Mohler  k  Liebig, 
'^  Ann,  Fharm,  11,  146.) 

rr 

^  c.  Chlorosulphidb  op  Nitrogen.    NS',  SCI. 

StUphazoHc  Chloride  of  Sulphur,  CMorosulphure  azoHque. 

1.  The  compound  of  one  atom  of  chloride  of  sulphur  with  one  atom  of 
ammonia  (p.  485)  heated  in  a  fflass  tube  for  some  hours  at  a  temperature 
of  100°,  is  converted  (without  further  alteration)  into  a  yellow  mixture  of 

I  sal-ammoniac  and  chlorosulpbide  of  nitrogen. 

4(NH»,  SCI)  »  3(NH»,  HCl)  +  NS*C1. 
This  mixture  has  a  peculiar  odour.     When  strongly  heated  it  gives 
off  sal-ammoniac,  and  is  likewise  resolved,  into  nitrogen  gas,  chloride  of 
sulphnr,  and  sulphur. 

NS*C1  =  N  +  B«C1  +  28. 

It  dissolves  perfectly  in  water ;  the  solution,  which  has  a  peculiar 
smell,  and  at  first  a  yellow  colour,  becomes  turbid  after  a  while,  and 
slowly  deposits  a  brown  powder.  The  now  colourless  solution  contains 
ammonia,  hydrochloric,  hyposulphurous,  sulphuric  acid,  and  a  trace  of  hy- 
dro-sulphunc  acid ;  but  no  sulphuric  acid  is  formed,  as  long  as  the  liquid 
continues  yellow.  If  the  small  quantities  of  the  insoluble  brown  powder, 
sulphur,  and  sulphide  of  nitrogen  are  disregarded,  the  decomposition  will 
be  as  follows: 

NS4C1  +  4H0  =  NH',  HCl  +  2S«0«.  (Soubdran.) 

The  brown  powder,  after  being  washed  with  water  till  no  more  chlo- 
rine is  removed,  then  with  cold  alcohol,  and  lastly  with  boiling  ether— 
which  dissolves  out  sulphide  of  nitrogen  together  with  a  small  quantity  of 
sulphur  and  traces  of  chlorine— and  afterwards  dried  in  vacuo,  behaves  in 
the  following  manner :  when  heated,  it  evolves  equal  measures  of  nitrogen 
and  ammoniacaJ  gas,  and  leaves  a  large  quantity  of  sulphur.  It  dissolves 
slowly  in  water,  yielding  a  solution  of  hjrposulphite  of  ammonia  with  a 
small  quantity  of  sal-ammoniac,  and  depositing  sulphur.  It  is  insoluble 
in  alcohol  and  ether;  but  if  a  piece  of  hydrate  of  potash  is  added  to  the 
alcohol,  the  compound  dissolves,  forming  a  fine  amethyst-coloured  solu- 
tion, which  gradually  loses  its  colour,  in  consequence  of  the  formation  of 
hyposulphite  of  potash.  Sulphide  of  sodium  instead  of  hydrate  of  potash 
produces  the  same  colour,  but  much  paler.  According  to  analysis,  the 
powder  contains  about  7  atoms  of  sulphur,  S  atoms  of  nitrogen,  ana  3  atoms 
of  hydrogen,  with  a  trace  of  chlorine.  (Soubeiran.)  According  to  Bineau, 
{Ann,  Chim.  Phys.  70,  268)  the  same  brown  powder  is  obtained,  mixed 
however  with  a  large  quantity  of  sulphur,  when  the  compound  of  proto- 
chloride  of  sulphur  with  2  atoms  of  ammonia  is  treated  with  water.  The 
new  compound  dissolves  in  bisulphide  of  carbon  much  more  abundantly 
than,  sulphur,  and  crystallizes  from  the  solution,  on  spontaneous  evapora- 
tion, in  brilliant  brownish  red  crystals.  According  to  the  same  authority, 
it  contains  one  atom  of  nitroffen  and  one  atom  of  hydrogen,  combined 
apparently  with  2  atoms  of  sulphur. 

2.  When  dry  carbonic  acid  gaa  is  passed  through  a  hot  solution  of 
sulphide  of  nitrogen  in  protochloride  of  sulphur,  a  small  quantity  of  chlo- 


476  NITROGEN. 

vosulpliide  of  nitrogen  sublimes  after  a  while  in  yellow  crystals.  The 
latter  compound  Is  characterized  by  giving  a  bine  colour  with  ammonia. 
(Soubeiran,  Ann.  Chim.  Phy$.  67,  87,  &  101 ;  also  J.  Pharm.  24,  64,  8c 

75.) 

B.  Aqua-Reoia. 

Nitromuriatic  acid,  Eonifftwasser,  Goldscheidemuser,  Acide  Nvtro- 
muriatique. 

Formation  and  Preparation. — By  mixing  aqueous  nitric  and  hydro- 
chloric acids;  by  dissolving  a  nitrate  in  aqueous  hydrochloric  acid;  by 
dissolving  a  hydrochlorate  or  metallic  chloride  In  aqueous  nitric  acid.  la 
all  these  cases,  the  liquid  gradually  becomes  yellow^  but  with  peculiar 
rapidity  when  heated,  because  the  hydrogen  of  the  hydrochloric  acid 
(Sch.  67)  or  of  the  metal  in  the  metallic  chloride,  becomes  oxidized, 
and  chlorine  and  hyponitric  acid  are  thereby  produced.  In  a  close  vessel, 
the  decomposition  and  separation  of  chlorine  are  arrested  as  soon  as  the 
liquid  is  saturated  with  the  gas ;  but  in  an  open  vessel,  from  which  the 
chlorine  can  escape  as  fast  as  it  is  evolved,  the  action  continues  till  either 
the  whole  of  the  nitric  acid  or  the  whole  of  the  hydrochloric  acid  or 
metallic  chloride  present  is  decomposed.  (Berzelius.)  If  the  liquid  be 
heated  till  it  disengages  no  more  chlorine,  it  loses  the  power  of  dissolving 
gold.  (H.  Davy,  QuaH.  J.  of  Sc.  1,  67;  also  6?»^6.  57,296).  A  mix- 
ture of  hydrochloric  acid  gas  and  hyponitric  acid  vapour  cannot  be  made 
to  condense ;  aqueous  hydrochloric  acid  may  indeed  be  mixed  with  hypo- 
nitric acid,  but  the  mixture  does  not  dissolve  gold.  (H.  Davy.)  The 
usual  proportions  for  aqua-regia  are  1  part  of  nitric,  and  between  2  and 
3  parts  of  hydrochloric  acid. 

Yellow,  fuming,  highly  corrosive  liquid,  used  for  dissolving  those 
metals  in  hydrochloric  acid,  which  have  but  a  feeble  affinity  for  oxygen. — ; 
When  metals  are  dissolved  in  aqua-regia,  the  nitric  acid  is  almost  entirely 
converted  into  nitric  oxide  gas.  On  the  assumption  that  a  metal—- copper, 
for  example — dissolves  as  chloride,  we  have : 

3Cu  +  NO*  +  3HCI  =  3CuCl  +  3HO  +  NO«j 

on  the  assumption  that  it  dissolves  in  the  form  of  hydrochlorate  of  the 
oxide : 

3Cu  +  NO*  +  3HC1  =  3(CuO,  HCl)  +  N0«. 

A  mixture  of  hydrochloric  acid  of  a  certain  degree  of  dilution,  with 
nitric  acid  perfectly  free  from  hyponitric  acid,  is  not  resolved  at  ordinary 
temperatures  into  chlorine  and  hyponitric  acid,  and  consequently  does  not 
attack  several  of  the  metals,  such  as  arsenic,  antimony,  platinum,  &c. 
The  action,  however,  commences  on  gently  heating  the  mixture,  or  on 
adding  a  small  quantity  of  nitrite  of  potash.  Hence  the  presence  of 
nitrous  acid,  whether  it  be  produced  by  the  mutual  decomposition  of  the 
two  acids  on  exposure  to  heat,  or  directly  added  to  the  mixture,  is  requi- 
site for  setting  up  the  action  on  the  metal.  The  addition  of  chlorine  does 
not  produce  any  effect.  (Millon,  vid.  also  pp.  398,  399.) 

IT  The  nature  of  aqua-regia  has  been  further  investigated  by  E.  Davy 
and  Baudrimont,  and  more  lately  by  Gay-Lussac.  According  to  E.  Davy, 
the  peculiar  properties  of  aqua-regia  are  due  to  the  presence  of  a  com- 
pound which  he  calls  chloro-nit7^u^  acid,  consisting  of  equal  volumes  of 
chlorine  and  nitric  oxide:   this  compound  is  evolved  as  a  gas  of  an 


AQUA-REGIA.  477 

orange-yellow  colour,  when  common  saU  or  chloride  of  potassium  is  acted 
upon  by  strong  nitric  acid.  Baudrimont  {J,  Pharm,  5,  49),  by  heating  a 
mixture  of  2  parts  (by  weight)  of  nitric  acid  and  3  of  hydrochloric  acid, 
to  a  temperature  of  86°  (177°  F.),  and  passing  the  evolved  gases  through 
a  cooled  U-tube,  for  the  purpose  of  condensing  free  hydrochloric  acid, 
obtained  a  red  gas  which  reddened  moist  litmus  paper  and  bleached  it 
after  some  hours,  but  had  no  effect  on  dry  litmus  paper.  It  attacked  gold 
and  platinum ;  arsenic  and  antimony  took  fire  when  thrown  into  it  in  the 
state  of  powder;  on  phosphorus,  even  when  melted,  it  had  no  effect. 
When  passed  through  a  tube  surrounded  with  ice  and  salt,  it  condensed  to 
a  liquid  of  a  deep  red  colour,  which,  as  well  as  the  gas  itself,  dissolved 
readily  in  water.  At  the  temperature  of  0°,  water  took  up  121  times  its 
Tolume  of  the  gas,  forming  a  liquid  of  a  bright  red  colour.  This  com- 
pound, which  Baudrimont  calls  ckloro-nitric  aad^  is  composed,  according 
to  his  analysis,  of  1  atom  of  nitrous  acid  and  2  atoms  of  chlorine,  NO^ 
CP;  its  formation  may  be  expressed  as  follows : 

NO*  +  2HCI  =  NO»Cl*  +  2H0. 
This,  however,  does  not  explain  the  evolution  of  free  chlorine,  which 
always  takes  place  on  heating  a  mixture  of  nitric  and  hydrochloric  acids. 
Gay-Lussac  has  shown  that  when  the  gases  evolved  from  aqua-regia 
at  the  temperature  of  boiling  water  are  passed  through  tubes  surrounded 
with  a  freezing  mixture,  a  cloudy,  lemon-coloured  liquid  is  obtained,  whose 
composition  is  expressed  by  the  formula,  NO',CPj  it  may  be  reffarded  aa 
hyponitric  acid,  in  which  2  atoms  of  oxygen  are  replaced  by  chlorine;  it 
may  therefore  be  called  Hyp<hchhr<mUric  acid.  Its  formation  is  thus 
represented : 

NO*  +  3HC1  ^  NO«Cl«  +  3HO  +  CI. 

and  this  accounts  for  the  liberation  of  chlorine,  which  is  an  invariable  con- 
comitant of  the  action.  Hypo-chloronitric  acid  is  immediately  decomposed 
by  water,  forming  a  solution  which  contains  hydrochloric  acid,  but  no  free 
chlorine : 

N0«C1"  +  2HO  =  2HC1  +  NO*. 

Hypo-chloronitric  acid  is  not,  however,  the  only  product  of  the  decomposi- 
tion of  aqua-regia  by  heat.  The  condensed  product  also  contains  another 
liquid,  composed  of  1  atom  of  nitric  oxide  and  1  atom  of  chlorine,  NG^CI : 
this  may  be  regarded  as  nitrous  acid  in  which  1  atom  of  oxygen  is 
replaced  by  chlorine :  Gay-Lussac  distinguishes  it  by  the  name  of  Gklo- 
ronitrous  acid.  It  may  likewise  be  formed  by  allowing  nitric  oxide  and 
chlorine  to  condense  together  in  a  vessel  surrounded  by  a  freezing  mix- 
ture; but  even  then,  the  product  is  not  a  definite  body;  for  the  propor- 
tions of  nitric  oxide  in  the  less  volatile  portions  are  much  greater  than  in 
the  more  volatile.  When  common  salt  is  heated  with  nitric  acid,  a  mix- 
ture of  hypochloric  and  chloronitrous  acids  is  evolved,  in  various  propor- 
tions depending  upon  the  strength  of  the  acid,  the  temperature,  &c. 
When  gold  is  acted  upon  by  aqua-regia,  the  products  of  decomposition  are 
exactly  the  same,  viz.,  chloronitric  vapour,  water,  and  free  chlorine; 
moreover,  the  chlorine  alone  is  retained  by  the  gold,  while  the  chloro- 
nitric vapour  passes  off,  just  as  when  the  liquid  is  simply  heated.  Hence 
it  appears  that  the  peculiar  action  of  aqua-regia  on  metals,  &c.,  is  due  to 
the  free  chlorine  evolved  in  its  decomposition.  (Gay-Lussac,  Ann.  Chim. 
Fhys,  33,  203;  also  Ann,  Pharm.  66,  213;  abstr.  Q.  J.  of  Ohem,  Soc.  1, 
340.)  IT 


478  NITROGEN. 


G.    a.  Htdroohlorats  of  Ammonia. 

JfuriaU  of  AfMnmiia,  CMaride  of  Ammonium,  S<U^mmoniae ,  Sakiauru 
Ammoniak^  Salmiak,  Muriate  d' Ammoniague,  HydrochioraU  dammo- 
niaqus^  Chlorurect Ammonium,  Chlorure  ammonique,  Sal  ammoniacum. 

Found  native  near  yolcanos^  on  the  burning  mountain  of  Dnttweiler 
(Olaser,  Kattn,  Arch.  14,  169),  and,  in  yery  small  quantity,  in  sea  water 
and  certain  mineral  waters. 

Equal  volumes  of  hydrochloric  acid  and  ammoniacal  gases  rapidly  con- 
dense mto  solid  sal-ammoniac,  the  combination  being  attended  with  eyo- 
lution  of  heat. 

Preparation, — 1.  Egyptian  method  of  preparing  Sal-ammoniac,  In 
Egypt,  sal-ammoniac  is  sublimed  from  the  soot  obtained  by  burning 
camels' dung.  (Vid.  Taschenh,  1780,  53.) — 2.  Liige  method  of  preparing 
sal-ammoniac.  A  mixture  of  coal,  common  salt,  animal  matter,  and  clay, 
is  burned  in  peculiarly  constructed  ovens,  and  the  soot  obtained  in  this 
manner  is  afterwards  sublimed. — 3.  European  method  of  preparing  sal- 
ammoniac.  The  impure  carbonate  of  ammonia  obtained  by  the  destruc- 
tive distillation  of  solid  animal  matter,  or  by  the  distillation  of  putrid 
urine,  is  either  directly  converted  into  chloride  of  ammonium  by  treating 
it  with  hydrochloric  acid,  chloride  of  calcium,  chloride  of  magnesium,  or 
chloride  of  aluminum;  or  it  is  first  converted  into  sulphate  of  ammonia  by 
sulphuric  acid,  sulphate  of  iron,  or  gypsum,  and  the  sulphate  afterwards 
converted  into  chloride  by  means  of  common  salt. — The  salt  is  generally 
separated  from  the  other  substances  by  sublimation,  whereby  it  is  often 
obtained  in  grey  or  brown  coloured  cakes  of  a  fibrous  texture.  It  ia 
purified  either  by  a  second  sublimation  on  the  small  scale,  or  by  solution 
m  water,  filtration,  and  crystallization;  by  the  latter  method  it  is  ob- 
tained in  fine  crystals:  Flowers  of  Sal-ammoniac,  Purified  Sal^mmoniac, 


Properties,    Regular  octohedrons,  cubes,  trapezohedrons  (Fig,  1,  2, 


however,  is  evolved  when  the  aqueous  solution  is  boiled  (Soubeiran, 
J,  Pharm,  12,  242);  when  heated,  it  volatilizes  undecomposed,  and  with- 
out previously  fusing.  [For  the  specific  gravity  of  the  vapour,  vid,  I.,  280.] 
Permanent  in  the  air;  of  a  sharp  saline  taste;  neutral. 

Kir.       Bu-      Bene- ; 

Calcalation.  wan.     choU.       Uus.  '  Vol.  Sp.  gr. 

NH' 170  ....  31-8  ....  25  ....  31  ....  3195    AmmoniAcal gas i  ....  029465 

HCl 36-4  ....  68-2  ....  75  ....  69  ....  68-05    Hydrochloric  add  gaa  i  ....  0-63090 

NH8,HCl53-4  ....100-0  ....100  ...,100  ....10000      Vapour 1  ....  0*92555 

Potassium  heated  with  sal-ammoniac  forms  chloride  of  potassium, 
and  disen^iges  2  volumes  of  ammoniacal  gas  to  1  volume  of  hydro^ 
gen.  (H.  Davy.)  Iron  and  other  metals  act  in  a  similar  manner,  but 
less  energetically.  The  resulting  metallic  chlorides  frequently  unite 
with  the  ammonia  set  free,  or  with  undecomposed  sal-ammoniac. — A 
mixture  of  sal-ammoniac  and  chlorate  of  potash  is  decomposed  below 
the  boiling  point  of  oil  of  vitriol,  evolving  a  gas  which  smells  strongly  of 
chlorine.  (Soubeiran.)    [For  the  decomposition  of  sal-ammoniac  by  chlo- 


HYPOCHLORITE  OF  AMMONIA.  479 

ride  of  phosphorns,  vid,  p.  437.]  When  exposed  to  the  air,  sal-ammoniac 
loses  ammonia  and  becomes  acid  to  test  paper]  if  it  be  heated  to  the 
subliming  point,  then  cooled  and  dissolved  in  cold  water,  it  recovers  its 
neutrality;  but  if  dissolved  in  hot  water,  it  loses  ammonia  and  again 
acquires  an  acid  reaction.  (Emmet.)  Upon  this  ready  volatiliiation  of 
ammonia  depends  in  part  the  power  which  an  aqueous  solution  of  sal- 
ammoniac  (and  other  ammoniacal  salts)  possesses  of  dissolving  insoluble 
carbonates  and  other  salts. — One  part  of  sal-ammoniac  dissolves  at  18*75^ 

i 65-75**  F.),  with  great  decrease  of  temperature,  in  2*7  parte  of  water, 
brming  a  solution  of  specific  gravity  1*08  (Karsten).  From  a  saturated 
solution,  strong  hydrochloric  acid  precipitates  a  portion  of  the  sal-ammo- 
niac, (A.  Vogel,  J,  pr.  Chem.  2,  199.)  Sal-ammoniac  dissolves  in  about 
its  own  weight  of  boiling  water;  it  is  very  sparingly  soluble  in  alcohol. 

Dry  sal-ammoniac  powder  placed  in  a  vessel  surrounded  with  ice, 
absorbs  the  vapour  of  anhydrous  sulphuric  acid  very  abundantly  and 
without  disengagement  of  gas;  the  product  is  a  translucent  mass  which 
is  flexible  at  first,  but  afterwards  becomes  hard.  The  maes,  when  heated, 
first  evolves  hydrochloric  acid  gas,  and  then  the  products  of  decompo- 
sition of  sulphate  of  ammonia.  The  addition  of  a  few  drops  of  water 
converts  it,  with  violent  evolution  of  hydrochloric  acid  gas,  into  ordinary 
sulphate  of  ammonia;  a  similar  result  is  produced  by  exposure  to  moist 
air.  The  compound  cannot  be  formed  from  anhydrous  sulphate  of  ammon 
and  hydrochloric  acid  gas.  (H.  Rose,  Pogg.  38, 118; — vid.  also  Berwlius, 
JahresbericlU,  16,  139;— Kane,  Ann.  Chim.  Phya.  72, 139.)— In  the  same 
manner,  pure  nitrate  of  potash  absorbs  anh;^drous  sulphuric  acid  at  ordi- 
nary temperatures  without  disengaging  nitric  acid ;  hydrochlorate  of  am- 
monia possesses  the  same  property. 

b.  Htpoohlobite  of  Ammonia. 

A  mixture  of  very  dilute  hypochlorous  acid  and  ammonia— even  when 
the  ammonia  is  in  excess— decolorizes  solution  of  sulphate  of  indigo,  and 
continues  to  evolve  bubbles  of  nitrogen  till  it  is  completely  decomposed. 
(Balard.) — When  a  carefully  prepared  solution  of  chloride  of  lime  is  pre- 
cipitated with  a  quantity,  not  quite  sufficient  for  complete  saturation,  of 
a  mixture  of  sesqui-carbonate  of  ammonia  and  enough  caustic  ammonia 
to  prevent  efiervescence  (or  with  phosphate  or  oxalate  of  ammonia),  and 
the  liquid  decanted  from  the  insoluble  carbonate  of  lime,  a  similar 
solution  is    obtained.      This  liquid  when  heated,  effervesces  strongly, 

fives  off  bubbles  of  nitrogen  gas,  and  becomes  acid.     The  salt  is  also 
estroyed  by  evaporation  in  vacuo,  sal-ammoniac  alone  remaining.  (Sou- 
beiran,  Jnn.  Chim.  Phys.  48,  141.) 

IT    c.  Chlorite  op  Abimonia. 

Formed  by  saturating  the  aqueous  solution  of  chlorous  acid  with  am- 
monia. The  solution  bleaches  vegetable  colours,  even  when  the  ammonia 
is  in  excess.  This  salt  has  not  been  obtained  in  the  solid  state,  for  the 
solution  cannot  be  concentrated  without  decomposition.  (Berzelius,  TraiUt 
3,  294.)  H 


480  NITIIOGEK. 


d,    HlTPOCHLORATB  OF  AmMONIA  1 

Aqneons  solation  of  ammonia  abeorbe  chloric  oxide  gaa.  The  yellow 
liquid  obtained  continualij  evolves  nitrogen  gas  and  leaves  chlorate  of 
ammonia  on  evaporation.  (Soubeiran,  Ann.  Chim.  Phys.  48,  140.) 


e.  Chlorate  of  Ammonia. 

1.  Formed  by  mixing  an  aqueous  solution  of  chloric  acid  with  caustic 
ammonia  or  carbonate  of  ammonia.  (Gay-Lussac.) — 2.  By  precipitating 
chlorate  of  baryta,  strontia  or  lime,  with  carbonate  of  ammonia.  (Che- 
nevix.)— 3.  By  adding  finely-divided  chlorate  of  potash  in  small  portions  at 
at  a  time,  to  an  aqueous  solution  of  fluoride  of  silicium  and  ammonium,  as 
long  as  fluoride  of  silicium  and  potassium  continues  to  be  formed — ^and  then 
filtering  the  solution.  (Berzelius). — The  salt  crystallizes  in  fine  needles ;  has 
a  very  pungent  taste.  According  to  Vauquelin,  it  appears  to  volatilize 
below  the  boiling  point  of  water. — When  placed  on  a  hot  surface,  it  ex- 
plodes a  with  red  light,  like  burning  nitre ;  if  the  salt  is  decomposed  by  a 
gentle  heat,  a  mixture  of  chlorine,  nitrogen,  and  a  small  quantity  of 
oxygen,  or  more  probably  nitrous  oxide  gafi,  is  obtained,  a  small  quan- 
tity of  sal-ammoniac,  with  excess  of  acid,  remaining  behind.  (Vauquelin.) 
The  crystals  sometimes  explode  spontaneously  when  kept.  (Mitscherlich, 
Pogg,  52,  85.) — Very  soluble  in  water  and  alcohol.  (Chenevix.) 


/.  Perchlorate  of  Ammonia. 

Colourless,  transparent  prisms  belonging  to  the  right  prismatic  sys- 
tem {Fig,  53);  in  this  figure,  the  prisms  are  supposed  to  be  seen  from 
above  :  u\u  =  103°  12';  y  :y  =  102*»  5'.  (Mitscherlich,  Pogg.  25,  300.) 
—It  dissolves  in  5  parts  of  cold  water ;  the  solution  is  neutral,  but  gives 
off*  ammonia  when  evaporated,  and  becomes  acid ;  from  the  latter  solution, 
concentrated  perchloric  acid  precipitates  the  neutral  salt  by  absorbing 
water.  Sparingly  soluble  in  alcohol.  (Serullafl,  Ann,  Chim,  Phyi,  46, 
304.) 

g,  Chlorocarbonate  of  Ammonia. 

A  mixture  of  1  measure  of  phosgene  with  4  measures  of  ammoniacal 
cas  condenses,  with  great  disengagement  of  heat,  to  a  white,  tasteless 
body,  which  is  volatile,  of  a  saline  pungent  taste,  and  without  action  on 
vegetable  colours.  (J.  Davy.) 

Calculation.  Volume. 

2NH*    340  40-77  Ammoniical  gas    4 

COCl    49-4  59-23  Phosgene  gas 1 

2NH»,COCl  83-4  10000 

When  treated  with  aqueous  phosphoric,  sulphuric,  or  nitric  acid,  the 
compound  evolves  a  mixture  of  2  measures  of  hydrochloric  acid  with 
1  measure  of  carbonic  acid  gas.  Aqueous  hydrochloric  acid  also  decom- 
poses it.  Acetic  acid  dissolves  it  without  effervescence.  It  may  be  sub- 
limed in  an  atmosphere  of  carbonic  acid,  sulphurous  acid  or  hydrochloric 


CHLOROCARBONATE  OF  AMMONIA.  481 

acid  gas,  without  undergoing  decomposition.      Deliquesces  in  the  air. 
(John  Davy.)     Soluble  in  alcohol,  but  not  in  ether.  (Regnault.) 

RegnauU  (Ann.  Chim.  Phya,  ^9^  180;  also  J.  pr.  Chem.  18,  101)  re- 
gards it  as  a  mixture  of  sal-ammoniac  and  a  compound  called  Carbamide, 
which  contains  1  atom  of  carbonic  oxide  and  1  at<im  of  amidogen: 

2iNH»,  COCl  =  NH^Cl  +  NH«,  CO. 
This  view,  however,  has  not  yet  been  established  by  the  actual  separation 
of  sal-ammoniac  from  carbamide,  but  is  founded  upon  the  fact  that  an 
aqueous  solution  of  chlorocarbonate  of  ammonia  evolves  carbonic  acid  gas 
on  the  addition  of  strong  nitric,  hydrochloric,  or  sulphuric  acid,  but  not  on 
the  addition  of  the  same  acids  when  dilute,  or  of  acetic  or  oxalic  acid; 
the  aqueous  solution,  also,  when  supersaturated  with  ammonia,  does  not 
precipitate  chloride  of  barium.  Consequently,  the  aqueous  solution  does 
not  actually  contain  ordinary  carbonate  of  ammonia  ready  formed,  but 
probably  a  compound  of  carbonic  oxide  with  amidogen. 

h.    CULOROBORATE   OF   AmMONIA. 

One  volume  of  chloroborio  acid  gas  condenses  1^  vol.  ammoniacal  gas, 
producing  a  white  substance  which  is  rather  less  volatile  than  sal-ammo- 
niac, and  sublimes  undecomposed.  Water  decomposes  it,  forming  hydro- 
chlorate  and  borate  of  ammonia.     (Berzelius.) 

t.  Ammonio-terchloride  op  Phosphorus. 

Dreifach'Chlorpho8pkor'Ammo7iiak, 

Terchloride  of  phosphorus  rapidly  absorbs  ammoniacal  ffas,  the  action 
being  attended  with  the  formation  of  a  white  cloud,  and  great  rise  of 
temperature.  Terchloride  of  phosphorus  freed  from  excess  of  phosphorus 
by  repeated  distillation,  is  surrounded  with  a  freezing  mixture  and  satu- 
rated  with  ammoniacal  gas,  which  is  very  slowly  evolved,  so  that  no  rise 
of  temperature  may  take  place.  (H.  Kose.)  The  resulting  compound 
should  be  white,  and  dissolve  slowly  but  completely  in  water;  if  heat  is 
disengaged  during  the  absorption,  the  substance  becomes  covered  with 
brownish  spots  and  is  partially  resolved  into  sal-ammoniac,  phosphorus, 
and  phosphide  of  nitrogen,  the  latter  of  which  remains  behind  in  brownish 
flakes  on  dissolving  the  compound  in  water.  (H.  Rose.)  But  even  when 
heat  is  entirely  avoided  in  its  preparation,  the  compound  gives  up  a  large 
quantity  of  sal-ammoniac  to  cold  water  or  alcohol;  whence  it  appears  to 
undergo  partial  decomposition,  even  at  ordinary  temperatures.  (W5hler 
&  Liebig.) 

White  rough  powder.     (H.  Rose.) 

Calculation.  H.  Rose.  Penoz. 

5NH3   85-0  38-18  32-98 

P       31-4  1411  1     g- ^2 

3C1     106-2  47-71  47-31  f    ^^  ^^ 

5NH3,PC1» 222-6  100-00  10000 

Persoz  (Ann.  Chim.  Php.  44,  321)  is  of  opinion  that  the  compound 
contains  4  atoms  of  ammonia  to  I  atom  of  chloride  of  phosphorus. 

When  ammonio-terchloride  of  phosphorus  is  heated  to  redness  in  a 
current  of  carbonic  acid  gas,  it  is  resolved  into  hydrogen,  ammoniacal  gas, 
VOL.  ir.  2  I 


482  NITROGEN. 

vapour  of  phosphorns^  and  a  residue  of  pHospbide  of  nitrogen.  5  atoms 
of  the  componnd  contain  25N,  75H,  5T,  and  1501;  in  the  decompofidtion, 
15(NH»,  HCl),  2NH»,  4PN*  are  formed,  and  9H  and  IP  are  set  free; 
hence  f  of  the  phosphorus  goes  to  form  phosphide  of  nitrogen.  According 
to  experiment,  also,  100  parts  of  the  componnd  yield  21*27  parts  of  phos- 
phide of  nitrogen,  containing  11  "18  parts  of  phosphorus  [nearly  ^  of  the 
phosphorus,  11*29  bein£^  the  exact  amount].  When  the  compound  is 
heated  in  the  open  air,  tne  same  products  are  obtained;  but  the  residual 
phosphide  of  nitrogen  is  coloured  brownish-red  (which  changes  to  white 
erety  time  it  is  heated)  from  the  presence  of  phosphorus,  and  frequently 
also  contains  chlorine.  (H.  Rose.) — The  quantity  of  hydrogen,  however, 
which  is  disengaged  when  the  compound  is  ignited  in  a  current  of  carbonic 
acid  gas  is  so  small  that  its  presence  is  probably  accidental,  arising  merely 
from  hydroscopic  moisture;  hence  the  decomposition  may  take  place  as 
follows : 

2(5NH>,  Pa^)  =  6(NH«,  HCl)  +  2NH=»  +  N«P  +  P. 

(Wohler  &  Liebig,  Ann,  Pharm,  11,  139.)— When  thrown  into  fused 
potash  it  is  violently  decomposed,  heat  and  light  being  disengaged,  am- 
monia set  free,  and  a  fused  mass,  perfectly  soluble  in  water,  left  behind. 
When  fused  with  carbonate  of  potash  or  soda,  it  evolves  ammonia  and 
yields  a  residue  consisting  of  chloride  of  potassium  and  phosphate  of 
potash.  Again,  when  boiled  for  a  considerable  time  with  an  aqueous 
solution  of  pure  potash  or  carbonate  of  potash,  it  evolves  ammonia  and 
yields  a  solution  of  chloride  of  potassium  and  phosphite  of  potash.  (H, 
Kose.)  Hot  nitric  acid  dissolves  it  slowly  but  completely,  with  evolution 
of  nitric  oxide  gas;  the  solution  contains  hydrochloric  acid  and  phosphoric 
acid.  Hot  sulphuric  acid  dissolves  it  with  disengagement  of  hydrochloric 
acid.  Hydrochloric  acid  forms  with  it  a  solution  containing  phosphorous 
acid.  (H.  Rose.)  The  compound,  when  slightly  moistened  with  concen- 
trated hydrochloric  acid,  becomes  strongly  heated,  and  afterwards  dis- 
solves with  ease  in  cold  water,  as  though  the  hydrochloric  acid  had  sepa- 
rated the  ammonia,  whereupon  the  chloride  of  phosphorus  is  decomposed 
by  the  water,  with  rise  of  temperature.  (Wohler  &  Liebig.)  It  dissolves 
slowly  but  completely  in  water;  the  neutral  solution  may  be  supposed  to 
contain  hydrochlorate  and  phosphite  of  ammonia, 

6NH%PC1»  +  3HO  =  3(NH%HC1)  +  2NH»,P0»; 
nevertheless  solution  of  platinum  precipitates  only  part  of  the  ammonia; 
whence  the  solution  would  appear  to  contain  a  peculiar  compound  of 
ammonia.  (H.  Rose.)    Solution  of  ammonia  neither  decomposes  nor  dis- 
solves the  compound. 

h.  Ammonio-pentachloride  of  Phosphorus. 

Funfach-CAlorphosphor-Ammoniak. 

It  is  yet  doubtful  whether  pentachloride  of  phosphorus  can  combine 
with  ammonia,  without  decomposition. 

Sir  H.  Davy  was  the  first  who  prepared  this  compound,  viz.,  by  heat- 
ing chloride  of  phosphorus  in  ammoniacal  gas,  the  ess  being  absorbed, 
with  development  of  heat.  In  this  manner  he  obtained  a  white  inodorous, 
tasteless  powder,  which,  if  it  had  not  absorbed  moisture^  might  be  heated 
in  close  vessels,  even  to  whiteness,  without  alteration.  [This  substanoe 
was,  doubtless,  phosphide  of  nitrogen,  left  behind  after  the  expulsion  of 


AMMONIO-PENTACHLORIDE  OF  PHOSPHORUS.  483 

sal-ammoniac,  &c.] — When  exposed  to  the  action  of  flame,  it  exhibited  a 
slight  appearance  of  combustion,  colouring  the  flame  yellow  and  leaving 
phosphoric  acid.  When  fused  with  hydrate  of  potash,  it  burned  feebly  and 
gave  ofi*  ammoniacal  gas ;  the  residue  consisted  of  a  mixture  of  phosphate 
of  potash  and  chloride  of  potassium.  It  was  not  altered  by  boiling  with 
water,  or  with  sulphuric,  hydrochloric,  or  nitric  acid,  or  solution  of  potash. 

Grouvelle  ^Ann.  Chim.  Phy%,  17,  37;  also  Schw,  33,  432)  obtained  a 
compound  which  was  immediately  decomposed  by  solution  of  potash, 
with  disengagement  of  ammonia,  and  gradually  dissolved  in  water,  yield- 
ing a  solution  of  neutral  phosphate  and  hydrochlorate  of  ammonia,  so  that 
it  must  have  contained  1  atom  of  pentachloride  of  phosphorus  to  7  atoms 
of  ammonia. 

According  to  H.  Rose  {Pogg,  24,  311),  pentachloride  of  phosphorus 
absorbs  dry  ammoniacal  gas  with  great  rapidity.  The  resulting  white 
mass  contains  59*34  per  cent,  of  chlorine,  and  consequently  about  5  At. 
ammonia  to  1  At.  chloride  of  phosphorus.  This  compound,  when  heated 
out  of  contact  of  air,  yields  the  same  products  of  decomposition  as  the 
ammonio-terchloride  of  phosphorus.  When  thrown  upon  fused  hydrate  of 
potash,  it  forms  a  mixture  of  chloride  of  potassium  and  phosphate  of  pot- 
ash, with  disengagement  of  heat  and  light  and  evolution  of  ammonia.  It 
is  dissolved  by  long  digestion  in  aqueous  ammonia,  carbonate  of  potash, 
nitric  acid,  or  sulphuric  acid ;  with  the  latter,  however,  it  gives  off"  hydro- 
chloric acid;  it  also  dissolves  imperfectly  in  water. 

By  his  more  recent  experiments,  however.  Rose  has  been  led  to  doubt 
{Pogg.  52,  61)  the  existence  of  such  a  compound.  If  pentachloride  of 
phosphorus  is  reduced  to  a  very  low  temperature  by  means  of  a  freezing 
mixture  and  ammonia  slowly  passed  into  it,  the  gas  is  scarcely  if  at  all 
absorbed.  When  the  reduction  of  temperature  is  not  so  great,  aosorption 
takes  place,  accompanied  with  considerable  disengagement  of  heat ;  and 
from  the  mass  thus  saturated  with  ammonia,  water  extracts  sal-ammoniac 
free  from  phosphoric  acid,  while  phosphide  of  nitrogen  is  left  undissolved. 

Wohler  &  Liebig  also  found  {Ann.  Pharm.  11,  139),  that  when  pen- 
tachloride of  phosphorus  is  saturated  at  a  low  temperature  with  ammonia, 
cold  water  merely  dissolves  out  sal-ammoniac,  unaccompanied  by  phos- 
phoric acid,  from  the  white  mass  obtained.  But  even  alter  washing  the 
mass  for  weeks,  the  wash-water  still  contained  sal-ammoniac,  which 
appeared  to  be  obstinately  retained  by  the  phosphide  of  nitrogen ;  on 
boiling  with  potash,  however,  and  then  with  dilute  sulphuric  or  nitric 
acid,  the  sal-ammoniac  was  more  rapidly  separated.  Besides  sal-ammo- 
niac and  phosphide  of  nitrogen,  Wohler  &  Liebig  also  obtained  chloro- 
|>hosphide  of  nitrogen  by  the  action  of  water  (p.  474). 

I.  Ahmonio-diohloribb  of  Sulphur.    2NH',S^C1. 

HaUhGhhrtchwrfel'amfMmiaJe.     CklorosuiphiU  ^ammxmiague. 

Vapour  of  dichlorlde  of  sulphur  is  mixed  with  ammoniacal  gas  in  a 
glass  globe.  The  compound  may  be  exposed  to  the  air  for  a  long  time 
without  suffering  decomposition.  It  dissolves  in  absolute  alcohol;  water 
precipitates  sulphur  from  the  solution,  and  gives  rise  to  the  formation  of 
hydrochlorate  and  hyposulphite  of  ammonia. 

2NH»  +  S»C1  +  HO  »  NH»,Ha  +  NH»,  SO  +  S.  (Martens.) 


2  I  2 


484  NITHOGEK. 

M,  Ammonio-protochloride  op  ScLPirrR. 

E  infadi-  Chorschwefel-ammon  ial\ 

The  combination  of  protochloride  of  snlphur  with  ammonia  is  attended 
with  great  rise  of  temperature,  whereby  it  may  again  be  resolved  into 
sal-ammoniao,  nitrogen  gas,  and  snlphnr. 

a.  With  2  Atoms  of  Ammonia. — CMorure  deSoufre  bi-ammoniacal. 
Preparation. — 1.  Ammoniacal  gas  is  evolved  from  lime  and  sal-am- 
moniac in  a  flask,  and  first  passed  through  a  small  quantity  of  water  con- 
tained in  a  Woulfe's  bottle,  that  the  rapidity  of  its  evolution  may  be  ob- 
served— then  through  a  long  tube  filled  with  hydrate  of  potash  in  order 
to  dry  it — and  thence,  through  a  glass  tube  bent  at  right  angles — to  the 
bottom  of  a  glass  vessel  of  20  to  25  litres  (4^6  gallons)  capacity.     The 
top  of  the  basin  is  covered  with  two  semicircular  pieces  of  slate,  &c.,  one 
of  which  has  an  opening  in  its  centre  for  the  passage  of  the  ammonia 
tube,  the  other  a  slit  so  situated  as  to  come  just  over  the  middle  of  the 
vessel.     Through  this  slit  pass  four  large  threads  united  at  top  to  a  piece 
of  wood,  and  connected  at  the  other  end  with  a  flat  piece  of  slate  which  is 
thus  suspended  in  the  basin ;  on  the  plate  are  put  six  small  colour-saucers 
(of  porous  earthenware).  As  soon  as  the  glass  is  filled  with  ammoniacal  gas, 
the  second  piece  of  slate  is  moved  a  little  on  one  side— 'the  plate  with  the 
saucers  drawn  up — a  few  drops  of  protochloride  of  sulphur  poured  into 
each  of  them — and  the  whole  again  lowered  into  the  glass  j  then,  when 
the  dense  fumes  at  first  produced  have  subsided,  the  plate  is  drawn  up  as 
before,  and  fresh  saucers  containing  protochloride  of  sulphur  are  intro- 
duced.    The  chloride  of  sulphur  must  be  perfectly  saturated  with  chlo- 
rine, by  Soubeiran's  method,  (p.  833).     No  rise  of  temperature  must  take 
place;  hence  the  experiment  is  best  performed  in  winter.     For  the  same 
reason,  it  is  necessary  to  use  a  large  vessel,  and  to  introduce  the  chloride 
of  sulphur  by  small  quantities  at  a  time.     The  saucers  also  in  which  the 
chloride  of  sulphur  is  placed,  must  be   of  considerable  thickness  and 
changed  every  time,  so  that  they  may  exert  as  much  cooling  action  as 
possible.     The  glass  vessel  should  not  become  sensibly  warm.     It  is  also 
necessary  that  the  ammonia  be  in  excess;  otherwise,  a  blue  and  red  sub- 
stance is  produced,  which  cannot,  without  considerable  difilculty,  be  con- 
verted into  the  required  compound  by  a  subsequent  excess  of  ammonia. 
When  the  experiment  has  been  properly  conducted,  the  sides  and  bottom 
of  the  glass  vessel  become  covered  with  loose,  dirty  yellow  flakes.     The 
tube  and  plates  are  then  removed,  and  a  glass  plate  luted  over  the  mouth 
of  the  vessel  while  still  full  of  ammoniacal  gas.     On  the  following  day, 
when  the  flakes  have  acquired  a  pure  yellow  colour,  the  ammoniacal  gas 
is  expelled  from  the  vessel  by  a  current  of  air,  and  lastly  the  flakes  are  ex 
posed  to  the  air  in  thin  layers,  till  they  no  longer  smell  of  ammonia. — 2.  The 
compound  containing  1  atom  of  ammonia  is  first  prepared  and  then  exposed 
to  an  atmosphere  of  ammoniacal  gas,  till  it  has  taken  up  an  additional 
atom  of  ammonia.     During  the  absorption,  the  compound  becomes  first 
green,  and  then  yellow,  but  without  any  observable  rise  of  temperature. 
Pale,  lemon-coloured  flakes:  ciystallizable  from  a  solution  in  ether. 
Inodorous. 

Calculation  according  to  Soubeiren. 

2NH'» 34-0  39'81 

SCI    51-4  60-19 

2NH»,  Sa  85-4  100*00 


AMMONIO-PROTOCHLORIDE  OF  SULPHUR.  485 

In  vacuo,  the  compound  loses,  in  14  hours,  0*2  per  cent,  of  am- 
moniaj  in  48  hours,  1*6;  and  in  96  hours,  2*3  per  cent.  When  gently 
heated  in  a  glass  tube,  it  first  gives  off  pure  ammoniacal  gas,  then  the 
same  gas  mixed  with  nitrogen,  together  with  sulphur  and  sal-ammoniac, 
sulphide  of  nitrogen  being  sublimed  throughout  the  process.  This  deoom  • 
position  commences  at  a  temperature  between  S5°  and  40^,  continues 
slowly  at  100®,  but  proceeds  more  rapidly  between  100"*  and  240°,  in  a  cur- 
rent of  hydrogen  or  ammoniacal  gas.  Oil  of  vitriol  decomposes  the  com- 
pound with  violence,  combining  with  the  ammonia  and  setting  chloride  of 
sulphur  at  liberty ;  at  the  same  time,  however,  a  small  quantity  of  chloride 
of  sulphur  escapes  together  with  1  atom  of  ammonia.  Cold  water  like- 
wise decomposes  the  compound,  separating  sulphide  of  nitrogen  at  first 
in  the  form  of  a  yellow  powder,  and  forming  a  yellow  solution,  which,  in 
addition  to  hydrochlorate  and  hyposulphite  of  ammonia,  contains  a  pecu- 
liar substance— probably  a  compound  of  NS^,  SCI  with  ammonia — ^but 
the  yellow  colour  quickly  disappears  (more  rapidly  on  the  addition  of  an 
acid),  and  even  the  sulphide  of  nitrogen  disappears  in  the  course  of  a  few 
days;  after  that,  the  colourless  solution  contains  only  hydrochlorate  and 
h3rposttlphite  of  ammonia.  With  hot  water,  these  changes  are  effected 
with  great  rapidity ; 

2NHSSC1  +  HO  =  NH^HC1  +  NH3,S0. 

The  sulphide  of  nitrogen  separated  at  the  commencement,  contains  at 
most  one-third  of  the  sulphur  preseut  in  the  compound.  The  addition  of 
an  acid  to  the  water  does  not  increase  this  quantity.  The  compound  pre- 
pared by  the  first  method  always  leaves  a  small  quantity  of  yellowish 
white  sulphur  behind  when  digested  in  water,  because  the  heat  evolved 
during  the  absorption  of  the  ammonia  by  the  chloride  of  sulphur  causes  a 
partial  decomposition.  This  sulphur,  which  Gregory  supposed  to  be  sul- 
phide of  nitrogen,  contains  only  traces  of  nitrogen  and  ammonia.  The 
compound  prepared  by  the  second  method  dissolves  completely  in  water. 
Alcohol,  when  it  contains  only  a  small  quantity  of  water,  acts  on  the  com- 
pound like  pure  water. 

The  compound  dissolves  but  sparingly  in  absolute  alchohol  or  ether, 
forming  a  yellow  solution,  from  which  it  crystallizes  on  evaporation,  though 
a  portion  is  always  decomposed  at  the  same  time.  (Soubeiran.) 

p.  With  1  Atom  of  Ammonia.— C%Zor?^rtf  deSoufre  ammoniacal. 

Preparation. — Similar  to  that  of  the  compound  with  2  atoms  of  am- 
monia, according  to  the  first  method,  excepting  that  the  ammoniacal  gas 
is  introduced  very  sparingly  into  the  large  glass,  and  the  saucers  contain, 
ing  the  protochloride  of  sulphur  are  renewed  before  the  red  compound  /3 
is  converted  into  the  yellow  compound  «;  but  evenif  asmall  quantity  of  the 
yellow  compound  should  be  formed,  it  rapidly  disappears  on  mixing  it  with 
the  red,  which  contains  a  portion  of  free  chloride  of  sulphur.  A  small 
quantity  of  ammoniacal  gas  is  lastly  introduced,  in  order  to  saturate  the 
excess  of  chloride  of  sulphur  above  mentioned.  (Soubeiran.) 

Bulky  brownish-red  flakes;  not  volatile;  have  a  peculiar  odour 
resembling  that  of  chloride  of  sulphur.  (Soubeiran.)  The  compound  does 
not  redden  litmus;  has  a  saline,  extremely  pungent  taste,  and  may  be 
Volatilized.  (Martens.) 


486  NITBOG£N. 

Calculation.  Soubeiran. 

NH» 17-0  24-85  24*98 

S     16-0  23-39  23-39 

CI    35-4  51-76  51-63 

NH»,SC1 68-4" 100-00  lOO'OO 

This  compound  turns  yellow  when  heated  in  a  tube  to  110^;  and  if 
kept  at  that  temperature  ior  some  hourS;  it  is  completely  converted  into 
a  yellow  mixture  of  sal-ammoniac^  chloride  of  sulphur,  and  nitrogen, 
without  any  evolution  of  gas. 

4(NHSSC1)  =  3(NH^HCl)  +  NS*,C1. 

When  this  mixture  is  more  strongly  heated,  it  yields  nitrogen  gas, 
sulphur,  chloride  of  sulphur,  and  sal-ammoniac.  (Soubeiran.)  Oil  of 
vitriol  expeb  chloride  of  sulphur  from  it,  and  forms  sulphate  of  am- 
monia. (Martens,  Soubeiran.)  Concentrated  nitric  or  hydrochloric  acid, 
however,  does  not  expel  the  chloride  of  sulphur.  (Martens.)  Hot  water 
dissolves  a  tolerably  large  quantity  of  the  compound,  and  separates  a  soft 
brown  substance,  which,  when  the  water  is  heated  for  a  long  time,  first 
becomes  paler,  then  assumes  a  greenish  colour,  and  is  finally  converted 
into  pure  yellow  sulphur;  the  solution,  which  is  yellowish-brown  at  first, 
becomes  colourless  sifter  a  while,  and  deposits  sulphur  containing  traces 
of  nitrogen  and  ammonia,  (in  consequence  of  the  decomposition  of  the  hypo- 
sulphurous  acid  formed  at  the  commencement);  after  this,  it  contains  hydro- 
chlorate  and  sulphite  of  ammonia  with  excess  of  acid.  Cold  water  pro- 
duces the  same  effect  in  the  course  of  a  few  days.  Solution  of  ammonia 
decomposes  the  liquid  more  rapidly,  likewise  separating  a  small  and 
yariable  quantity  of  sulphur.  (Soubeiran.)  The  compound  does  not 
attract  moisture  from  the  air  only,  unless  it  contains  chloride  of  sulphur. 
(Soubeiran.) 

It  dissolves  readily  in  alcohol  and  ether.  The  alcoholic  solution  is 
dark  yellow,  and  on  the  addition  of  water  deposits  sal-ammoniac,  while 
hyposulphurous  acid  remains  in  solution;  the  latter  is  afterwards  resolved 
into  sulphurous  acid  and  sulphur,  which  carries  down  with  it  a  small 
quantity  of  the  original  compound.  Both  the  alcoholic  and  the  ethereal 
solution  give  precipitates  with  aqueous  solutions  of  lead  and  silver  salts 
the  precipitate  consisting  of  a  mixture  of  metallic  chloride  and  hyposul- 
phite of  the  oxide.  (Soubeiran.) 

n.  Carbonate  op  Ammonio-Chloride  of  Sulphur. 

Carbonate  of  chloride  of  sulphur  gradually  absorbs  a  large  quantity  of 
ammoniacal  gas;  the  compound  is  liquid  at  brst,  but  becomes  solid  as  the 
quantity  of  ammonia  increases.  Its  taste  is  first  sharp,  and  afterwards 
sulphurous.  When  pure,  it  may  be  sublimed  without  decomposition;  but 
if  even  a  small  quantity  of  water  is  present,  it  fuses  on  exposure  to  heat, 
and  gives  off,  first  ammoniacal  gas,  then  an  ethereal  liquid  smelling  of 
hydrocyanic  acid,  then  sulphurous  acid,  and  lastly  a  sublimate  of  hydro- 
chlorate  and  sulphite  of  ammonia.  When  exposed  to  the  air,  it  absorbs 
water  of  crystallization  without  deliquescing.  Dissolves  in  water,  proba- 
bly forming  a  solution  of  carbonate,  sulphite,  and  hydrochlorate  of  ammo- 
nia. (Berzelius.) 


SULPHATE  OF  CHLORIDE  OF  SULPHUR  AND  AMMONIA.       48  7 


0,  Sulphate  of  Ammonio-Chloride  of  Sulphur. 

A  quantity  of  pentasulphate  of  chloride  of  Balpbur  being  cooled  down 
to  a  low  temperature^  ammoniacal  gas  is  very  slowly  passed  into  it,  so 
that  no  rise  of  temperature  may  take  place ;  and  the  tolerably  saturated 
compound  thus  obtained  is  reduced  to  powder,  and  left  in  contact  with 
ammoniacal  gas  for  several  months,  the  gas  itself  being  frequently  renewed. 
When  heat  is  disengaged  during  the  absorption,  the  compound  acquires  a 
yellow  colour,  from  formation  of  anhydrous  sulphite  of  ammon ;  and  its 
aqueous  solution,  when  treated  with  solution  of  silver,  gives  a  precipitate 
which  is  coloured  yellow  from  the  presence  of  sulphide  of  silver. 

Pure  white  mass. 

On  subliming  it,  a  small  quantity  of  yellow  anhydrous  sulphate  of 
ammon  is  produced.  It  is  not  deliquescent  but  dissolves  readily  in 
water.  The  solution,  when  evaporated  in  vacuo  over  oil  of  vitriol,  yields 
a  crystalline  crust  which  has  the  property  of  remaining  moist  fur  a  long 
time,  but,  when  completely  dry,  possesses  the  same  composition  as  tho  ori* 
ginal  compound  before  solution  in  water. 

From  the  aaueous  solution,  bichloride  of  platinum  precipitates  chloride 
of  platinum  and  ammonium;  chloride  of  barium  separates  only  a  portion 
of  the  sulphuric  acid,  so  that  the  filtrate  again  becomes  turbid  after  long 
standing;  chloride  of  strontium  gives  no  precipitate  except  on  boiling; 
nitrate  of  silver  throws  down  chloride  of  silver.  (H,  Rose.) 

Calculation.  H.  Rose. 

9NH3 153-0  32-20 

6S     96-0  20-20  20-350 

3C1   106-2  22-35  22-243 

ISO  120  0  25-25 

4NH',  SCP  +  5(NH',  80=*)  475-2  10000 

The  composition  of  the  compound  is  such  that  when  it  is  dissolved 
in  water,  6  atoms  of  anhydrous  sulphate  of  ammon  and  8  atoms  of  sal* 
ammoniac  may  be  produced. 

9NH3  +  SC1>  +  580^  +  3HO  =  6(NH»,SO*)  +  3(NH»,HC1).    (H.  Rote.) 


p.  Chloride  op  Iodine  and  Ammonium.    NH^C1,ICP. 

CMoroiodite  cPAmmoniaque, — 1.  One  part  of  iodate  of  ammonia  is 
heated  in  a  flask  with  8  parts  of  concentrated  hydrochloric  acid  to  a  tem- 
perature between  40°  and  50°;  and  when  the  whole  of  the  iodate  of  am- 
monia is  dissolyed,  the  yellow  solution  obtained  is  suffered  to  cool. 
NH3,  lO*  +  6HC1  =  NH«C1  +    ICP  +  2C1  +  5H0. 

2.  A  concentrated  solution  of  hydriodate  of  ammonia  is  saturated  with 
chlorine  gas.  The  salt  obtained  in  this  manner  crystallizes  more  readily 
and  in  greater  purity  than  the  former : 

NHn  +  4C1  =  NH*C1  +  ICP. 

3.  Solution  of  sal-ammoniac  is  mixed  with  solution  of  terchloride  of 
iodine. 

Long,  golden-yellow  crystals,  which,  when  rapidly  heated,  yolatilize 
without  decomposition.  When  exposed  to  a  gentle  heat  for  a  long  tim^^ 
the  whole  of  the  terchloride  of  iodine  is  driven  off,  and  pure  sal-ammoniap 


488  NITROGEN. 

left  behind.  Ammonia,  potash,  or  soda  precipitates  iodine  from  the  solu- 
tion,— the  two  latter,  with  disengagement  of  ammonia.  With  other  bodies 
this  compound  exhibits  reactions  corresponding  to  those  of  the  chloride  of 
iodine  and  potassium.  (Filhol,  J.  Fharm,  25,  441.) 

Calculation  according  to  Filhol. 

NH*Cl   53-4     18-7 

ICl"     232-2     81-3 

NH'Cl,  ICP  ~r.~ 285-6     1000 

Nitrogen  and  Fluorine. 
A.  Hydrofluate  op  Ammonia. 

rt.     MoNonyDROFLUATB.     Fluoride  of  Ammonium. 

According  to  Sir  H.  Davy,  ammoniacal  gas  unites,  without  separation 
of  water,  with  hydrofluoric  acid  evolved  from  a  mixture  of  fluorspar  and 
oil  of  vitriol.  The  anhydrous  salt  is  also  obtained  by  heating  a  dry  and 
finely  powdered  mixture  of  1  part  of  sal-ammoniac  and  2  J  parts  of  fluoride 
of  sodium  in  a  platinum  crucible ;  the  cover  is  placed  upon  the  crucible  in 
an  inverted  position,  and  water  frequently  dropped  upon  it  to  keep  it  cool; 
the  fluoride  of  ammonium  readily  sublimes  on  the  under  surface  in  small 
prisms  uncontaminated  with  sal-ammoniac.  If  the  mixture  is  at  all  moist, 
ammonia  is  disengaged  at  the  commencement,  and  a  corresponding  quan- 
tity of  bifluoride  is  sublimed  together  with  the  nionofluoride.  By  the  wet 
way,  this  compound  can  only  be  obtained  in  solution^  not  in  the  anhydrous 
state.  (Berzelius.) 

Permanent  in  the  air;  fuses  when  heated,  and  sublimes  at  a  lower 
temperature  than  sal-ammoniac;  has  a  very  pungent,  saline  taste.  Decom- 
posed by  potassium  at  a  red  heat  into  fluoride  of  potassium  and  a  mixture 
of  2  volumes  of  ammoniacal  gas  with  I  volume  of  hydrogen.  (H.  Davy.) 
When  exposed  to  the  air  in  contact  with  water,  it  evolves  ammonia,  even 
at  ordinary  temperatures,  and  is  converted  into  the  bi-acid  salt;  with  the 
aid  of  heat,  this  change  is  effected  more  rapidly.  It  attacks  glass,  not  only 
in  the  state  of  solution,  and  even  when  the  ammonia  is  in  excess,  (Wie^- 
lieb,  CrelL  N,  JSntdeck,  1,  13),  but  also,  according  to  Berzelius,  even  m 
the  dry  state — being  thereby  converted,  according  to  J.  Davy,  into  am- 
monia and  double  fluoride  of  silicium  and  ammonium.  A  solution  of  the 
salt  may  be  used  to  etch  on  glass.  It  dissolves  readily  in  water,  but 
sparingly  in  alcohol.  The  anhydrous  salt  absorbs  a  large  quantity  of 
ammoniacal  gas,  and  is  thereby  converted  into  a  basic  salt,  which  however 
again  loses  its  excess  of  ammonia  when  sublimed.  (Berzelius.) 

b,  BiHYDROFLU ATE. — Add  Flicorlde  of  A  ninwniitm. — Prepared  by  eva- 
porating an  aqueous  solution  of  the  mon-acid  salt  at  a  temperature  between 
36°  ana  40^,  whereby  half  the  ammonia  is  expelled,  (Berzelius.) — Or  an 
aqueous  solution  of  hydrofluosilicic  acid  may  be  decomposed  by  excess  of 
ammonia;  the  liquid  Altered  from  the  silica  through  linen  into  a  platinum 
dish  or  basin  and  evaporated;  any  remaining  silica  precipitated  by  a 
second  addition  of  ammonia ;  and  the  solution  again  filtered,  evaporated, 
and  set  aside  to  crystallize.  (Gm.)  Granular  (prismatic,  Gm.)  crys- 
tals, permanent  in  hot  air,  but  deliquescing  at  ordinary  temperatures, 
with  a  creeping  motion.  (Berzelius,  Pogg,  1,  17.)  When  heated,  it  vola- 
tilizes in  the  form  of  a  white  pungent  smoke,  which  acts  very  injuriously 
when  inhaledt 


NITRITE  OP  AMMONIA.  489 


B.    Ammonio-fluoride  of  Boron. 

a.  With  [At.  Ammonia. — A  mixture  of  equal  volumes  of  terfluoride 
of  boron  and  ammoniacal  gas  condenses  to  a  white,  opaque,  solid  body, 
which,  when  heated  in  close  vessels,  sublimes  unchanged,  but,  if  water 
is  present,  is  resolved  into  fiuoborate  of  ammonia  which  sublimes,  and 
boracic  acid  which  remains  behind.  It  dissolves  in  water,  yieldiug  a 
solution  of  hydrofiuate  and  borate  of  ammonia — or,  rather,  according  to 
Berzelius,  of  hydrofluate  of  boracic  acid  and  ammonia,  and  pure  borate 
of  ammonia.  (J.  Davy.) 

6.  With  2  At,  Ammonia. — One  volume  of  terfluoride  of  boron  mixed 
with  2  volumes  of  ammoniacal  gas,  forms  a  colourless  and  transparent 
liquid,  which,  when  heated  or  exposed  to  the  air,  or  treated  with  anhy- 
drous carbonic  acid  or  hydrochloric  acid  gas,  gives  up  its  excess  of 
ammonia,  and  is  converted  into  the  solid  compound  a.  (J.  Davy.) 

c.  With  3  At.  Ammonia. — One  volume  of  terfluoride  of  boron  com- 
bines with  3  volumes  of  ammoniacal  gas,  forming  a  liquid  which  corres- 
ponds in  its  properties  with  the  compound  6.  (J.  Davy.) 

Calculation.      J.  Davy.         Calculation.       J.  Davy.         Calculation.       J.  Davy. 
NH3  ....  170     20-26     20       2NH3     34-0    337     33        3NH»    510     43*26     43 
BF^   ....  66-9     79-74     80        BF»       66'9    66-3    67  BF     669    56'74     57 

a 83-9  100-00  100         b.       100-9  1000  100  c.     117-9  10300  100 

C.     Fluoborate  of  Ammonia. 

Boracic  acid  expels  3  atoms  of  ammonia  from  4  atoms  of  monohydro- 
fluate  of  ammonia,  and  produces  a  compound  of  1  atom  of  terhydro- 
fluate  of  boracic  acid  with  1  atom  of  monohydrofluate  of  ammonia, 
that  is  to  say,  a  double  hydrofluate  of  boracic  acid  and  ammonia ; 

4(NH^HF)  +  BO'  =  (NH^HF  +  B0^  3HF)  +3NH=»: 
this  again  is  converted  by  evaporation  into   a  compound  of  fluoride  of 
boron  with  hydrofluate  of  ammonia  or  fluoride  of  ammonium. 

NH^HF  +  B0»,3HF  =  (NH^F  +  BF')  +  3HO. 
By  sublimation,  it  may  be  freed  from  the  excess  of  boracic  acid  added  at 
the  beginning  of  the  process.  The  sublimate  is  white,  and,  when  deposited 
on  the  hotter  parts  of  the  vessel,  fused  and  transparent,  but  never  crys- 
talline. Fluoborate  of  ammonia  crystallizes  from  an  aqueous  solution  in 
small  six-sided  prisms  with  dihedral  summits.  It  tastes  like  sal-ammo- 
niac, and  reddens  litmus.  It  is  not  changed  by  mixing  with  ammonia 
and  subsequent  evaporation.  It  dissolves  with  great  facility  in  water, 
and  rather  freely  in  alcohol ;  the  aqueous  solution  does  not  attack  glass. 
(Berzelius.) 

According  to  Kuhlmann,  terfluoride  of  boron  is  capable  of  uniting 
with  nitric  oxide,  nitrous,  hyponitric,  and  nitric  acids. 

Nitrogen  with  Nitrogen. 

A.     Nitrite  of  Ammonia. 

1.  Prepared  by  decomposing  nitrite  of  lead  with  sulphate  of  ammo- 
nia, or  nitrite  of  silver  with  sal-ammoniac,  and  leaving  the  filtrate  to 
evaporate  in  the  air  or  in  vacuo,  at  ordinary  temperatures.— Or  by  passing 


490  NITROGEN. 

nitrons  acid  vaponr  into  solution  of  ammonia,  and  evaporating  over  lime. 
(Millon.) — Imperfectlj  crystallized  saline  mass,  which,  when  heated^  is 
resolved  into  water,  nitrous  oxide,  and  ammonia.  At  50%  (102°  F.) 
the  aqneons  solution  is  decomposed,  with  evolution  of  nitrogen  gas,  after 
which  it  remains  neutral,  (vid.  p.  372.)  Sck,  71,  (Bewelius,  §ilb.  40,  206.) 

NH*0,NO'  =  4110  +  2N. 
IT  The  decomposition  is  sudden  or  gradual,  accordingly  as  the  solution  is 
acid  or  alkaline.  A  single  drop  of  ammonia  added  to  the  neatral  solu- 
tion is  sufficient  to  render  the  decomposition  gradual ;  and  a  single  drop 
of  hydrochloric,  nitric,  or  sulphuric  acid,  causes  it  to  take  place  suddenly. 
On  this  is  founded  Millon's  method  of  preparing  the  salt  given  ahove. 
(Millon,  N.  Ann.  Chim.  Phys.  19,  255.)  IT— With  oil  of  vitriol,  the  salt 
oehaves  as  with  nitrate  of  ammonia.  (Pelouze.) 

Calculation.  Berzelius. 

NH» 17     26-56 

NO' 38     59-38 

HO 9     14-36     13-68 

NH',  HO,  NO^ 64     lOO'OO 


B.     Nitrate  of  Ammonia. 

Flammender  Saltpeter,  NUrum  fiamnutm, — A  neatral  mixture  of 
aqueous  nitric  acid  and  caustic  ammonia  or  carhonate  of  ammonia  is 
evaporated  and  set  aside  to  crystallize. — Crystallizes  in  six-sided  prisms 
with  six-sided  pyramids,  or  in  thin  needles ;  when  evaporated  to  a  very 
small  hulk,  it  solidifies  in  a  fibrous  or  dense  amorphous  mass.  Sp.  gr  = 
1 707  (Kopp.)     Has  a  sharp,  bitter,  unpleasant  taste. 

Crystallized.  H.  Davy.  Ure. 

Calcatatlon.  Beriellai.       KInrui.     Prinnstte.      Flbroui.  AttOTphoot. 

NH» 17-0  ....  21-25  ....  21-143  ....  23  ....  18-4  ....  19-3  ....  198  ....  233 

NO* 54-0  ....  67-50  ....  67*625  ....  57  ....  69*5  ....  72*5  ....  74*5  ....  65-0 

HO  9-0  ....  11-25  ....  11-232  ....  20  ....  121  ....     82  ....     57  ....  11*7 

Ni?gio,NO*  "somdTTZ.ioo-oo  .'.YoooooT!."iooT.7.iooo~ioo-oT^oo-~o~ioo-o' 

According  to  Dumas,  the  crystals  contain  not  1,  bat  2  atoms  of 
water. 

When  exposed  to  the  air,  it  loses  ammonia  and  acquires  an  acid  reac- 
tion. (Emmet.^  When  exposed  to  a  gradually  increasing  heat,  it  fuses 
and  is  resolvea,  with  effervescence,  into  nitrous  oxide  gas  and  aqueous 
vapour.  (Sch,  72.) 

NH»  +  N0»  -  2N0  +  3HO. 

The  salt  fuses  imperfectly  at  56*»  (las'*  P.),  perfectly  at  108'»  (226^ 
F.);  at  150°  (302®  F.)  it  evolves  white  fumes  which  condense  in  drops; 
at  175°  (347°  F.)  it  effervesces  slightly;  at  22o<»  (437°  F.)  rapidly;  at 
238^  (460°  F.)  it  begins  to  evolve  nitrous  oxide;  and  at  250°  (482°  F.) 
this  gas  is  evolved  in  abundance.  At  this  temperature,  which  remains 
constant  for  a  long  time,  a  small  quantity  of  nitrate  of  ammonia  sublimes 
unchanged.  The  residual  salt  (if  any  is  left  undecomposed)  solidifies  in 
a  crystalline  form  on  cooling.  (Pleischl.)  At  180*»  (356°  F.)  the  salt 
boils  without  being  decomposed,  as  decomposition  does  not  begin  below  a 
temperature  of  between  190°  and  200°.  (Legrand,  Ann,  Chim.  Phys,  59, 
435.)  Under  increased  pressure  the  decomposition  requires  a  higher 
temperature*  (Niemann.)  (p.  374.) — If  nitrate  of  ammonia  is  mixed  with 


NITRATE  OF  AMMONIA.  491 

an  equal  weight  of  chloride  of  calcium,  the  mixture  when  heated  evolves, 
not  nitrous  oxide,  but  nitrous  acid,  chlorine,  and  nitrogen  gas,  after 
which  eal-ammoniac  sublimes,  and  a  mixture  of  lime  and  chloride  of 
calcium  is  left  behind.  A  mixture  of  equal  weights  of  nitrate  of  ammo- 
nia and  chloride  of  potassium,  yields  on  exposure  to  heat,  nitrogen  gas, 
chlorine,  sublimed  sal-ammoniac,  and  a  residue  consisting  of  nitrate  of 
potash  and  chloride  of  potassium.  (Pleischl,  Schw.  38,  462.) — If  nitrate 
of  ammonia  is  heated  so  strongly  that  the  vessel  becomes  filled  with 
white  fumes,  nitric  oxide,  nitrite  of  ammonia,  and  free  ammonia  are 
evolved,  as  well  as  nitrous  oxide.  (Berzelius.)  When  rapidly  and  vio- 
lently heated,  as,  for  instance,  when  thrown  on  a  red-hot  porcelain  plate, 
it  bums  with  a  pale-yellow  light,  and  very  slight  noise,  and  gives  off 
water,  nitrous  acid  and  nitrogen  gas. — It  explodes  when  thrown  on  red- 
hot  charcoal.  Phosphorus  thrown  into  the  fused  salt  bums  with  a  bril- 
liant light  and  forms  phosphoric  acid — unless  the  phosphorus  is  in  excess, 
in  which  case  phosphoric  oxide  is  the  principal  product.  (Marchand,  J. 
pr.  Chem,  13,  442.) — Sulphur  undergoes  no  change  by  contact  with  the 
fused  salt,  but  most  of  the  metals  are  oxidized  by  it.  Zinc  disappears 
as  rapidly  in  the  fused  salt  as  in  an  acid,  and  evolves  so  much  heat,  that 
the  further  applicalion  of  heat  from  without  is  rendered  unnecessary,  the 
temperature  quickly  rising  from  between  138°  and  160*^,  at  which  the 
action  on  the  zinc  commences,  to  260°.  During  the  action,  nitrogen, 
ammoniacal  gas,  and  water  are  evolved,  but  no  nitrous  or  nitric  oxide. 
Lead  is  also  rapidly  oxidized,  with  disengagement  of  nitric  oxide  and 
hyponitrous  acid.  Antimony,  bismuth,  nickel,  copper,  and  silver  are 
oxidized  slowly;  arsenic,  tin,  iron,  and  mercury,  not  at  all.  (Emmet.) 
Silver  disengages  nitric  oxide  without  nitrous  oxido  and  forms  am- 
monio-nitrate  of  silver.  Spongy  platinum  likewise  appears  to  dis- 
engage nitric  oxide  only,  and  form  an  insoluble  platinum  compound. 
(L.  A.  Buchner,  Repert.  39,  360.) — A  mixture  of  nitrate  of  ammonia  and 
sal-ammoniac  in  a  state  of  fusion  dissolves  gold;  and  if  a  small  quan- 
tity of  nitrate  or  chlorate  of  potash  be  added,  it  oxidizes  and  dissolves  the 
whole  of  the  metals,  even  gold,  platinum,  rhodium,  and  iridium.  This 
mixture  likewise  dissolves  titaniferous  schorl,  chrome  iron  ore,  sulphide  of 
molybdenum,  and  pitchblende,  and  in  short,  the  greater  number  of  the  me- 
tallic oxides.  Litharge,  at  ordinary  temperatures,  expels  ammonia  from  the 
solid  salt.  (Emmet,  SUl.  Amer,  J.  18,  255.) — Nitrate  of  ammonia,  when 
treated  with  a  small  quantity  of  oil  of  vitriol,  is  resolved  into  sulphate  of 
ammonia  and  free  nitric  acid;  the  same  result  is  obtained  when  a  solution 
of  the  salt,  (dried  as  perfectly  as  possible,)  in  50  times  its  weight  of  oil  of 
vitriol,  is  heated  merely  to  a  temperature  between  90°  and  120*^;  but  on 
heating  it  to  150°,  it  evolves  nitrous  oxide  gas  mixed  with  a  small 
quantity  of  nitric  oxide,  hyponitric  acid,  and  nitric  acid  vapour,  and  leaves 
a  mixture  of  oil  of  vitriol  and  water.  When  the  quantity  of  oil  of  vitriol 
is  only  10  times  that  of  the  salt,  about  f  of  the  latter  is  resolved  into 
sulphate  of  ammonia  and  nitric  acid,  and  \  into  nitrous  oxide  and  water. 
(Pelouze,  Ann,  Chim.  Pkys,  77,  47;  also  Ann.  Pharm.  39,  312.)  One 
part  of  nitrate  of  ammonia  dissolves  in  0*502  parts  of  water  at  18°  (Kar- 
sten),  with  great  reduction  of  temperature;  it  dissolves  in  a  smaller 
quantity  of  hot  water.     Deliquesces  in  the  air. 


492  NITROGEN. 


C.    Sulphite  of  Nitric  Oxide  and  Ammonia. 

Nitrosuljykate  of  Ammonia^  NUrosulfate  d' Ammoniaque, — When  an 
aqneous  solution  of  sulphite  of  ammonia,  previously  cooled  down  bj  a 
freezing  mixture  till  it  begins  to  congeal,  is  brought  in  contact  with  nitric 
oxide  gas,  it  absorbs  the  gas  gradually  and  completely/'and  yields  crystals. 
— At  and  above  O'',  nitric  oxide  gas  decomposes  an  aqueous  solution  of 
sulphite  of  ammonia,  forming  sulphate  of  ammonia  and  a  half  volume 
of  nitrous  oxide  gas.  But  if  a  concentrated  solution  of  sulphite  of  am- 
monia is  mixed  with  5  times  its  bulk  of  aqueous  ammonia,  the  absorption 
of  nitric  oxide  gas  and  deposition  of  crystals  take  place  even  at  tempera- 
tures above  0°,  without  formation  of  nitrous  oxide.  Hence  an  excess  of 
ammonia  prevents  the  decomposition  of  the  double  sulphite  of  nitric  oxide 
and  ammonia. — The  crystals  obtained  are  washed  with  aqueous  ammonia 
— which  prevents  their  decomposition,  and  also  dissolves  them  less  freely 
than  pure  water — and  finally  dried  between  folds  of  bibulous  paper. 

Colourless,  transparent,  rhombic  prisms;  neutral  towards  vegetable 
colours;  of  pungent  and  slightly  bitter  taste. 

Calculation ,  according  to  Pelouze. 

NH»   17     19-32 

NO*   30     34-33 

SO«     32     36-36 

HO 9     10-23 

NHSNO*,SO»,  +  HO    ....    88    10000 

Tn  the  dry  state,  the  salt  remains  unchanged  at  110°;  at  a  somewhat 
higher  temperature  it  is  decomposed,  with  explosion  and  disengagement 
of  nitrous  oxide  gas.  When  thrown  on  glowing  coals,  it  is  decomposed 
with  emission  of  sparks.  It  gradually  deliquesces  in  the  air,  evolving 
nitrous  oxide  gas  and  yielding  pure  sulphate  of  ammonia.  In  water  it 
dissolves  at  first  without  decomposition,  but  is  afterwards  resolved — 
the  more  rapidly,  the  higher  the  temperature — into  nitrous  oxide  gas  and 
solution  of  sulphate  of  ammonia : 

NH\  NO«,  SO*  =  NH^  SO=>  +  NO. 
At  0°,  the  decomposition  is  effected  very  slowly;  at  40°,  with  rapid 
effervescence. — A  solution  of  the  compound  in  aqueous  ammonia  is  decom- 
posed in  the  same  manner,  but  much  more  slowly.  The  decomposition 
of  the  aqueous  solution  is  very  much  hastened  by  the  addition  of  charcoal, 
peroxide  of  manganese,  oxide  of  silver,  metallic  silver,  and  spongy  pla- 
tinum, which  nevertheless  do  not  thereby  undergo  any  chemical  change 
(I.,  1 14, 1 15).  Excess  of  ammonia  prevents  this  rapid  decomposition.  The 
stronger  acids,  also,  even  aqueous  solution  of  carbonic  acid,  and  solutions 
of  sesqui -chloride  of  chromium,  sulphate  of  ferrous  oxide,  sulphate  of 
copper,  sulphate  of  ferric  oxide,  corrosive  sublimate,  nitrate  of  silver  and 
acetate  of  lead  give  rise — even  at  some  degrees  below  0° — to  rapid  de- 
composition, accompanied  with  rapid  evolution  of  nitrous  oxide  gas, 
whilst  sulphuric  acid  and  ammonia  remain  in  the  liquid. — The  salt  does 
not  dissolve  in  alcohol,  even  when  hot,  and  is  precipitated  from  an 
aqueous  solution  on  the  addition  of  that  liquid.  (Pelouze,  Ann,  Chim, 
Phys,  60,  151.) 


493 


D.     Compound  op  Ammonio-chlortde  of  Sulphur  with 
Ammonio-sulphtde  op  Nitrogen. 

NH»,NS  +  NH'SCl. 

Formation,  When  protochloride  of  sulphur  is  slowly  dropped  into 
an  aqueons  solution  of  ammonia,  a  dark,  brownish-red,  soft  substance  i  s 
precipitated,  with  great  rise  of  temperature  and  formation  of  dense  fumes, 
but  no  evolution  of  gas;  the  same  substance  is  likewise  produced,  but 
without  the  fumes,  when  the  chloride  of  sulphur  is  poured  through  a 
funnel  to  the  bottom  of  a  vessel  filled  with  solution  of  ammonia. — The 
supernatant  liquid  contains  hydrochloiute,  hyposulphite,  and  sulphate  of 
ammonia,  besides  a  small  quantity  of  sulphur  mechanically  suspended. 
If  a  larger  quantity  of  chloride  oi  sulphur  is  used,  the  saturated  liquid 
assumes  a  lilac  tint;  after  which,  heat  is  evolved  and  the  mixture 
becomes  milky  from  separation  of  sulphur.  If  the  brownish-red  substance 
is  left  in  the  liquid,  it  continually  becomes  paler  and  is  converted  into 
Gregory's  light-yellow  sulphide  of  nitrogen  (p.  443).  If,  on  the  contrary, 
it  is  removed  from  the  liquid  immediately  after  its  formation,  it  rapidly 
becomes  heated,  swells  up,  and  is  soon  converted  into  the  same  pale 
yellow  substance.  Again,  if  it  is  freed  as  soon  as  possible  from  the 
supernatant  liquid  by  trituration  with  cold  water,  collected  on  a  filter, 
and  pressed  between  folds  of  bibulous  paper,  a  powder  is  obtained  which 
likewise  rapidly  becomes  heated,  swells  up,  and  changes  into  the  pale- 
yellow  compound. 

Preparation, — Protochloride  of  sulphur  is  added,  with  constant  stir- 
ring, to  aqueous  ammonia  diluted  with  an  equal  bulk  of  water,  the  quan- 
tities being  so  regulated  that  the  liquid  may  remain  alkaline,  and  not  be 
very  strongly  heated. 

Tlie  red  substance  formed  is  immediately  thrown  on  a  linen  filter, 
pressed  flat  in  cold  water,  in  order  to  keep  it  cool,  and  worked  up  with 
fresh  quantities  of  water. 

Brownish  red. 

Decompositions, — 1.  This  substance,  when  kept  under  water,  is  decora - 
posed  in  the  course  of  a  couple  of  days,  without  disengagement  of  gas; 
but  a  small  quantity  of  a  yellow  substance  is  separated,  and  a  solution 
formed,  containing  hydrochforate  and  hyposulphite  of  ammonia  with  a 
small  quantity  of  free  ammonia.  If  the  hyposulphurous  acid  be  converted 
into  sulphuric  acid  by  heating  the  liquid  with  chloride  of  soda,  it  is  found 
that  4  atoms  of  sulphuric  acid  are  present  for  each  atom  of  hydrochloric 
acid.  According  to  the  formula  given  by  Soubeiran,  the  red  compound 
should  yield  a  neutral  solution. 

NH%NS3  +  NH^  SCI  +  4H0  =  NH^  HCl  +  2(NH%S«0«). 
No  yellow  powder  is  formed  when  the  ammonia  used  in  the  preparation 
of  the  original  red  compound  is  cold  and  concentrated;  but  a  large  quan- 
tity separates  if  the  ammonia  has  been  previously  warmed  and  weakened 
by  the  addition  of  chloride  of  sulphur,  because  in  that  case,  sulphur  is 
precipitated. — 2.  The  red  compound  imparts  a  red  colour  to  solution  of 
ammonia.  (Soubeiran.) 


494  NITROGBN. 


Other  Compounds  op  Nitrogkn. 

a.  With  metals;  Metallic  Nitrides,  Azotures  Metalliques,  Stickstof- 
metalle. — 1.  A  few  metallic  oxides  and  chlorides,  when  heated  to  a  certain 
temperature  in  ammoniacal  gas,  are  converted  into  metallic  nitrides  hay- 
ing the  form  of  hrown  or  green  powders,  which  are  decomposed  at  higher 
temperatures,  sometimes  with  explosion;  snch  is  the  case  with  sesqui- 
chloride  of  chromium,  protoxide  of  copper,  protoxide  of  mercury,  &c.,  e,g, 

3HgO  +  NH'  =  Hg^N  +  3H0. 
2.  Ammoniacal  gas  is  much  more  easily  resolved  into  its  elements 
when  passed  through  a  tuhe  containing  red-hot  iron  or  copper,  than  when 
passed  through  an  empty  tube  at  the  same  temperature  (p.  42 1^.  The 
metals  are  thereby  rendered  brittle ;  their  specific  gravity  is  dimmished ; 
and  in  some  cases  their  colour  is  altered ;  frequently  also  they  sustain  an 
increase  of  weight,  due  to  the  nitrogen  which  they  have  taken  up.  Ou 
the  other  hand,  the  physical  characters  of  the  metal  are  often  altered 
without  increase  of  weight— -possibly  because  the  nitride  formed  at  the 
beginning  of  the  action  loses  its  nitrogen  at  a  later  period  (vid.  Potassium, 
Chromium,  Iron,  Copper,  Mercury). 

b.  Nitrogen  is  a  frequent  constituent  of  organic  compounds. 


APPENDIX. 


APPENDIX. 


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APPENDIX. 


499 


TABLE  II. 
Barometer  Scale  in  JdUlimetres  and  Inches, 


Mm. 

In. 

Mm. 

In. 

Mm. 

In. 

700 

«> 

27-560 

730 

.^ 

28-741 

760 



29-922 

701 

= 

27-690 

731 

= 

28-780 

761 

= 

29-961 

702 

^ 

27*638 

732 

^ 

28-819 

762 

= 

30-000 

703 

^ 

27-678 

733 

=z 

28-859 

763 

= 

30040 

704 

= 

27-717 

734 

= 

28-898 

764 

^ 

30-079 

705 

=: 

27-766 

735 

SZl 

28-938 

766 

^ 

30119 

706 

= 

27-795 

736 

= 

28-977 

766 

= 

30-168 

707 

=: 

27-835 

737 

= 

29-016 

767 

= 

30-197 

708 

= 

27-876 

738 

= 

29-056 

768 

=: 

30-237 

709 

= 

27-914 

739 

= 

29095 

769 

^ 

30-276 

710 

3^ 

27-963 

740 

=: 

29-134 

770 

= 

30-315 

711 

= 

27-992 

741 

^ 

29174 

771 

= 

30-355 

712 

= 

28032 

742 

m 

29-213 

772 

^ 

30-384 

713 

= 

28071 

743 

= 

29-252 

773 

= 

30-434 

714 

r= 

28111 

744 

=: 

29  292 

774 

= 

30-473 

716 

= 

28150 

745 

=: 

29  331 

775 

^ 

30-512 

716 

=r 

28189 

746 

= 

29-371 

776 

=s= 

30-562 

717 

:;s 

28-229 

747 

=r 

29-410 

777 

^ 

30-591 

718 

= 

28*268 

748 

rr: 

29-449 

778 

^ 

30-631 

719 

= 

28-308 

749 

= 

S9-489 

779 

= 

30-670 

720 

= 

28-347 

750 

= 

29-528 

780 

== 

30-709 

721 

= 

28-386 

751 

^sz 

29-567 

781 

^ 

30-749 

722 

=r 

28-426 

752 

r= 

29-607 

782 

= 

30-788 

723 

^ 

28-465 

753 

= 

29-646 

783 

=: 

30-827 

724 

= 

28-504 

764 

ssr 

29-685 

784 

ss 

30-867 

725 

= 

28-543 

755 

zsz 

29-725 

785 

= 

30-906 

726 

= 

28-583 

766 

= 

29-764 

786 

= 

30-946 

727 

= 

28-622 

757 

sr 

29-804 

787 

= 

30*985 

728 

=r 

28-661 

758 

^ 

29-843 

788 

^z 

31-024 

729 

= 

28-701 

759 

= 

29-882 

789 

^ 

31-063  ' 

28  inchei  =  711*187  millimetres. 

29  „  =  735-587           „ 

30  „  =  761-986           „ 

31  „  =  787-386            „ 


I  millimetre   =  0*03937  inch. 
•1  „  =  000394    „ 

•01  „  sz  0-00039    „ 


*1  inch  s  25*39954  millimetres. 
•1     „     =     2*53995  „ 

•01     „     =     0-25400  „ 

•001     „     =     0*02540  ,, 


500 


APPENDS. 


TABLE  III. 

For  converting  degrees  of  the  Centigrade  thermometer  into  degrees  of 
Fahrenheit's  Scale. 


Cent. 

Fah. 

Cent. 

Fah. 

Cent. 

Fall. 

-  100°  ... 

.  -  1480° 

-  60°  .... 

-  58-0° 

0"  .. 

.  +  320^ 

99   ... 

146-2 

49   .... 

5fi-2 

+   1   .. 

33  8 

98   ... 

144  4 

48   ... 

64-4 

2   ... 

35-6 

97   ... 

142-6 

47  .... 

62-6 

3   .. 

37-4 

96   ... 

140-8 

46   ... 

608 

4   .. 

39-2 

95   ... 

1390 

46   ... 

490 

6   ... 

410 

94   ... 

1372 

44   ... 

47  2 

6   ... 

42-8 

93   ... 

135-4 

43   ... 

46-4 

7   .. 

44-6 

92   ... 

1336 

42   ... 

43-6 

8   ... 

46-4 

91   ... 

131-8 

41   ... 

41-8 

9   ... 

48-2 

90   ... 

1300 

40   ... 

40-0 

10   ... 

600 

89   ... 

128  2 

39   ... 

38-2 

11 

61-8 

88   ... 

126-4 

38   ... 

30-4 

12   ... 

536 

87   ... 

124-6 

37   ... 

34-6 

13   .. 

65-4 

86   ... 

122-8 

36   ... 

328 

14   .. 

67  2 

85   ... 

1210 

35   ... 

310 

13   .. 

69-0 

84   ... 

119-2 

34   ... 

29-2 

16   .. 

60-8 

83   ... 

117-4 

33   ... 

27-4 

17   .. 

62  6 

82   ... 

115-6 

32   ... 

25-6 

18   .. 

64-4 

81   ... 

113-8 

31   ... 

23-8 

19   .. 

66-2 

80   ... 

1120 

30   ... 

22-0 

20 

680 

79   ... 

110-2 

29   ... 

20-2 

21   .. 

69-8 

78   ... 

108-4 

28   ... 

18-4 

22   .. 

71-0 

77  ... 

106-6 

27   ... 

166 

23   .. 

73-4 

76  ... 

104-8 

26   ... 

148 

24 

75-2 

76   ... 

1030 

25   ... 

130 

25 

770 

74   ... 

101-2 

24   ... 

11-2 

26   .. 

78-8 

73   ... 

99-4 

23   ... 

9-4 

27   .. 

80-6 

72   ... 

97-6 

22   ... 

76 

28 

82-4 

71   ... 

96-8 

21   ... 

6-8 

29 

84-2 

70  ... 

94-0 

20   ... 

40 

30   .. 

86-0 

69   ... 

92-2 

19   ... 

2-2 

31   .. 

878 

68   ... 

90-4 

18   ... 

0-4 

32   ... 

89-6 

67   ... 

88-6 

17   ... 

+  1-4 

3;j  ... 

91-4 

66   ... 

86-8 

16   ... 

3-2 

34   ... 

93  2 

66   ... 

86-0 

15   ... 

6-0 

35   ... 

950 

64   ... 

83-2 

14   ... 

6-8 

36   .. 

96-8 

63   ... 

81-4 

13   ... 

8-6 

37  ... 

98-6 

62   ... 

79-6 

12   ... 

10-4 

38   ... 

100-4 

61   ... 

77-8 

11   ... 

12-2 

39   ... 

102-2 

60   ... 

76-0 

10   ... 

140 

40   ... 

1040 

69   ... 

74-2 

9   ... 

15-8 

41   ... 

105-8 

68   ... 

72-4 

8   ... 

17-6 

42   ... 

1070 

67   ... 

70-6 

7  ... 

19-4 

43   ... 

109-4 

66 

68-8 

6   ... 

21-2 

44   ... 

111-2 

65   ... 

670 

6   ... 

230 

45   ... 

1130 

54   ... 

C5-2 

4   ... 

24-8 

46   ... 

1148 

53   .. 

63-4 

3   ... 

266 

47   ... 

116-6 

62 

61-0 

2   ... 

2«14 

48   ... 

118  4 

61   ... 

6S}-8 

1   .... 

30  2 

49 

120-2 

APPENDIX. 


501 


TABLE  III.— {condnv^d.) 


Cent. 

Fab. 

Cent. 

Fall. 

Cent. 

Fah. 

+  60^  .. 

.  +  1220° 

+  100°  .. 

..   +  212-0° 

+  150''  . 

...   +  302-0* 

61   .. 

123-8 

101 

213-8 

151   . 

303-8 

52 

125-6 

102   .. 

215-6 

152 

305  0 

63   .. 

127-4 

103   .. 

217-4 

153   . 

307-4 

64 

129-2 

104   .. 

219-2 

154 

309-2 

65 

1310 

106   .. 

2210 

155 

3110 

66 

132-8 

106   .. 

222-8 

156 

312-8 

67   .. 

1346 

107   .. 

224-6 

157   . 

314-6 

58   .. 

136-4 

108 

226  4 

;i68 

316-4 

59 

138-2 

109 

228-2 

159 

318-2 

60   .. 

1400 

110   .. 

230-0 

160 

3200 

CI 

141-8 

Ill 

231-8 

161   . 

321-8 

62 

143-6 

112 

233-6 

162   . 

323-6 

63   .. 

145-4 

113 

235-4 

163   . 

325-4 

64 

147-2 

114 

237-2 

164   . 

327-2 

65 

1490 

115   .. 

239-0 

165 

329-0 

66 

160  8 

116   .. 

240-8 

166 

330-8 

67   .. 

152-6 

117   .. 

2426 

167   . 

332-6 

68 

164-4 

118 

2.14-4 

168 

3.34-4 

69 

156-2 

119   .. 

246-2 

169 

336-2 

70   .. 

1580 

120 

2480 

170   . 

338-0 

71   .. 

159-8 

121 

249-8 

171   . 

339-8 

72   .. 

lGl-6 

122   .. 

261-6 

172   . 

341-6 

73   .. 

163-4 

1-23   .. 

253-4 

173   . 

343-4 

74   .. 

165-2 

124 

255-2 

174   . 

345  2 

75   .. 

167-0 

125 

257-0 

175   . 

3470 

70  .. 

168-8 

120   .. 

258-8 

176   . 

348-8 

77  .. 

170-C 

127  . 

260-6 

177  . 

350-6 

78  .. 

172-4 

128 

262-4 

178   . 

352-4 

79  .. 

174-2 

129 

264-2 

179   . 

354-2 

80   .. 

176  0 

130   .. 

266  0 

180 

3560 

81   .. 

177  8 

131 

267-8 

181   . 

357-8 

82 

1796 

132   .. 

269-6 

182 

359-6 

83 

181-4 

133 

2714 

183 

361-4 

84 

183-2 

134 

273  2 

184 

363-2 

85   .. 

1850 

135   .. 

2750 

105   . 

365-0 

86   .. 

186-8 

136 

2760 

186   . 

366-8 

87   .. 

188-6 

137   .. 

278  6 

187  . 

368-6 

88 

190-4 

138   .. 

280-4 

188   . 

370-4 

89 

192-2 

139 

2822 

189 

372-2 

90 

1940 

140   .. 

284-0 

190   . 

374-0 

91 

195-8 

141 

285-8 

191 

3758 

92   ., 

197-6 

142   .. 

287-6 

192 

377-6 

93   .. 

199-4 

143 

289-4 

193   . 

.379-4 

94 

201-2 

144 

291-2 

194 

3812 

95   .. 

203-0 

145   .. 

2930 

195 

303-0 

96   .. 

204-8 

140 

294  8 

l!i6 

,3848 

97   .. 

206-6 

147   .. 

2966 

197   . 

386-6 

98   .. 

208-4 

148   .. 

298-4 

198 

.-188-4 

99   .. 

2102 

149   .. 

300-2 

199   . 

390-2 

502 


APPENDIX. 


TABLE  111.— {continued,) 


Cent 

Fab. 

Cent. 

Fah. 

Cent. 

Fab. 

+  200°  ... 

.  +  392-0*' 

+  260^  . 

...  +  482*0° 

+  300^  . 

...   +  6720O 

201   ... 

393-8 

261   . 

483*8 

301   . 

6738 

202   ... 

396-6 

262 

485-6 

302   . 

675-6 

203   ... 

897-4 

263 

487-4 

303 

6774 

204   ... 

399-2 

254 

489-2 

304   . 

679-2 

205   ... 

4010 

266   . 

491-0 

306 

681-0 

206   ... 

402-8 

266   . 

492-8 

306   . 

682-8 

207   ... 

404*6 

267   . 

494-6 

307   . 

684-6 

208   ... 

4064 

258 

496-4 

308   . 

686-4 

209   ... 

408-2 

259   . 

498*2 

309 

688*2 

210   ... 

410-0 

260 

600-0 

310   . 

6900 

211 

411-8 

261   . 

601  8 

311   . 

6918 

212 

413-« 

262   . 

603-6 

312 

693-6 

213 

416-4 

203 

606-4 

313 

695-4 

214 

417-2 

264 

607-2 

314   . 

597*2 

216   .. 

419-0 

266 

609*0 

316 

6990 

216   .. 

420-8 

266 

610-8 

316   . 

600-8 

217   .. 

422-6 

267   . 

612*6 

317   . 

602-6 

218   .. 

424-4 

268 

614-4 

310 

604-4 

•219   .. 

426-2 

269 

616-2 

319 

606-2 

220   ... 

4280 

270   . 

618-0 

320 

608-0 

221 

429-8 

271   . 

619-8 

321 

609-8 

222   .. 

431-6 

272   . 

621*6 

322   . 

611-6 

223   .. 

433-4 

273   . 

623-4 

323 

613-4 

224   .. 

436-2 

274   . 

625*2 

324   . 

...  '   615-2 

226 

437-0 

276   . 

627-0 

326   . 

617-6 

226   .. 

438*8 

276   . 

628-8 

326   . 

618-8 

227   .. 

440-6 

277   . 

630-6 

327   . 

620-6 

228 

442*4 

278   . 

632-4 

328 

622-4 

229   .. 

444*2 

279 

634-2 

329   . 

6242 

230 

446-0 

280 

636-0 

330 

626*0 

231   .. 

447-8 

281   . 

637-8 

331   . 

6278 

232   .. 

449-6 

282 

639-6 

332 

629-6 

233 

451-4 

283   . 

641-4 

333   . 

631-4 

234 

463-2 

284   . 

643-2 

334   . 

633-2 

236   .. 

466*0 

286   . 

645.0 

335   . 

6-350 

236   .. 

456-8 

286 

646-8 

336   . 

636-8 

237   .. 

468-G 

287   . 

648-6 

337 

6386 

238 

460-4 

288   . 

650-4 

338   . 

6404 

239 

462-2 

289 

662-2 

339 

642-2 

240 

464*0 

200   . 

6640 

340   . 

644-0 

241   .. 

465-8 

291 

665-8 

341   . 

6468 

242 

467-6 

292   . 

657-6 

342   . 

647-6 

243   .. 

469-4 

293 

659-4 

343   . 

^19-4 

244 

471-2 

294 

661-2 

344 

6612 

246 

473-0 

296 

5630 

345   . 

6630 

246 

474-8 

296   . 

6G4-8 

346   . 

664« 

247   .. 

476-6 

297   . 

&66-6 

347   . 

666-6 

248 

478-4 

298 

568-4 

348 

668-4 

249   .. 

480-2 

299   . 

570-2 

349 

660-2 

APPENDIX. 
TABLE  IV. 


503 


Showing  the  elastic  force  of  condensable  gases  in  the  state  of  maximnm 
tension.  (Faraday,  FhiL  Trans,  1845.) 

The  marked  temperatures  are  those  which  were  determined  by  actaal  experiment 
Carbonic  Acid. 


Temp. 

Tension  in 

Temp. 

Tension  in 

Temp. 

Tension  in 

Fatf. 

Atmosphere. 

Fall. 

Atmosphere. 

Fali 

AtmoBpherc. 

—•111*^       . 

114 

-60° 

6-97 

—♦  4 

...       21-48 

110 

1-17 

♦66 

7*70 

0 

...       22-84 

*107 

186 

60 

8-88 

+♦5 

...       24-76 

100 

1-86 

40 

11-07 

•10 

...      26-82 

*95 

2-28 

*34 

12-60 

•16 

...       2909 

90 

2-77 

30 

13-64 

20 

...       30-65 

*  83 

3-60 

*23 

15-46 

*23 

...      33-16 

80 

3-93 

20 

..       16-30 

30 

...       37-00 

*76        . 

4-60 

*15 

J  7-80 

*32 

...       38*60 

70 

5-33 

10 

19-38 

Sulphuroue  Acid. 


Temp. 
Fah. 

Tension  in 

Temp. 
Falu 

Tension  in 

Temp. 

Tension  in 

Atmosphere. 

Atmosphere. 

Fall. 

0° 

0-726 

+  40" 

1-78 

+  76-8° 

3-60 

+   10 

0-920 

46-6 

2-00 

86 

400 

•14 

100 

*48 

2-06 

*90 

4-.S6 

♦10 

1-12 

*6« 

2-42 

93 

4-60 

♦23 

1-23 

68 

2'60 

98 

6-00 

*26 

1-33 

*64 

2-76 

•100 

6-16 

31-6      . 

1-60 

68 

3-00 

104 

6-60 

•32 

1-63 

*73-6 

3-28 

110 

600 

•33 

1-67 

Ilydrosulphuric  Add. 


Temp. 

Tension  in 

Temp. 

Tcnoion  in 

Tenjp. 

Tension  in 

Fall 

Atmosphere. 

Full. 

Atmosphere. 

Fall. 

Atmosphere. 

—  100» 

1-02 

—  60°       .. 

2-36 

0^      . 

610 

•94 

1-09 

46 

2-69 

+  *10 

7-21 

90 

116 

40 

2-86 

20 

8-44 

•83 

...       1-27 

30 

3-49 

*26       . 

9-36 

80 

1-33 

*24 

306 

30 

9-94 

•74 

1-60 

*20 

4-24 

40 

11-84 

70 

1-69 

*i6 

4-60 

•48 

13-70 

•68 

1-67 

10 

611 

60 

14*14 

60 

1-93 

*  2 

6-90 

*62 

14-60 

•58 

2-00 

504 


APPENDIX. 

TABLE  lV.—(contiHU€d.) 

Hj/drochlorie  Acid. 


Temp. 

Tension  in 

Temp. 

Tension  in 

Temp. 

Tension  in 

Fall. 

Atmosphere. 

Fuh. 

AtnuMphere. 

FaU. 

AUuoR^liere. 

—  100° 

1-80 

-•63° 

5*83 

-•6°       . 

13-88 

•  92 

2-28 

50 

6-30 

♦0 

15-04 

90 

2-38 

•42 

...        7-40 

+   10 

17-74 

♦  83 

2-90 

'  40 

7-68 

20 

2109 

80 

3-12 

♦33 

8-53 

•25 

23iW 

•77 

3-37 

30 

9-22 

30 

25-32 

70 

4*02 

•22 

...       10-86 

•32 

26-20 

*67 

4*26 

20 

..,       10-92 

40 

30-67 

80,     . 

5*08 

10 

...       12*82 

NitrcniB  Oxide. 


Temp. 

TeuAton  in 

Temp. 

Teniiion  iu 

Temp. 

Tension  in 

Fall. 

'" 

Atmosphere. 

l^ib. 

Atmospheie. 

—  126° 

1*00 

—  70° 

411 

—15°       . 

14-69 

120 

110 

65 

4-70 

10 

16-15 

115 

1-22 

GO 

5-36 

5 

17-70 

110 

...         137 

65 

609 

0 

19-34 

105 

1*55 

50 

6-89 

+  5        . 

21*07 

100 

1-77 

46 

...        7-76 

10 

22*89 

96 

203 

40 

...       8-71 

15 

24*80 

90 

234 

35 

...        974 

20 

26*80 

85 

2-70 

30 

...       10-85 

26 

28*90 

80 

311 

25 

...       1204 

30 

8110 

75 

3*58 

20 

...       13*32 

-    t     -  ■  ■ 

36 

33*40 

The  temperatures  in  this  table  are  all  within  \ialf  a  degree  of  tho.«e  actually  observed. 

Ammonia. 


Temp. 
Fuh. 


•0° 
+  0-6 

•9-3 
•18 
♦21 

258 
•26 
•32 
•33 

:i9*5 


Tension  in 
AtnKMphwe, 


2-48 
2*50 
300 
3-50 
3*72 
400 
404 
4-44 
460 
600 


Temp. 

Fall. 


Tension  iu      ■  Tomp. 
Atmosphere.        Fah. 


Atmosphere. 


+  •41° 

6*10 

^♦61*3°     .. 

7*00 

♦44 

5-36 

•G5-6       .. 

7-50 

•45 

6*45 

•67 

7-63 

45-8       .. 

6*50 

69-4 

8-00 

•49 

.         6*83 

73 

8*50 

•51*4 

600 

76-8 

900 

•62 

6*10 

80 

0*50 

•36 

6*38 

•83 

10*00 

•56'6        .. 

6-50 

85 

10-30 

♦60 

6*90 

Appaxaiti^. 


Plate  V. 


OfTuliiis  Chemistrif. 


REPORT 


THE   SECOND   ANNIVERSARY   MEETING 


CAVENDISH    SOCIETY. 


The  Anniversary  Meeting  of  the  Oayxndish  Society  for  the  year 
1849  was  held  at  No.  4,  Gordon  Square,  on  Thursday,  the  1st 
of  March,  at  three  o'clock  in  the  afternoon. 

The  chair  was  taken  hy  Thomas  Gkaham,  Esq.,  F.RS.,  Pbe- 
siDENT,  who  called  upon  the  Secbetaby  to  read 

THE  REPORT  OF  THE  COUNCIL. 

**  The  period  having  arrived  for  holding  the  Anniversary  of  the 
Catendibh  Society,  in  accordance  with  the  laws  made  at  the  General 
Meeting  in  July  last,  the  Council  present  to  the  memhers  a  state* 
ment  of  their  proceedings  during  the  time  they  have  been  in 
office. 

'*  This  Society,  although  established  in  1846,  was  not  fully  deve- 
loped or  actively  put  into  operation  until  last  year,  when  the  laws 


for  its  government  were  passed,  and  the  pablication  of  its  works 
commenced.  All  sabscriptions  which  had  been  previooslj  received 
were  made  to  refer  to  the  year  1848;  and  the  financial  report  which 
the  Council  have  now  to  lay  before  the  members,  will,  therefore,  in- 
clude the  whole  receipts  and  expenditure  of  the  Society  up  to  the 
present  time. 

"  At  the  period  of  the  last  General  Meeting,  the  Treasurer  had 
received  the  subscriptions  of  165  members,  in  addition  to  which  the 
names  of  368  gentlemen,  who  had  intimated  their  intention  of  join- 
ing the  Society  when  it  should  commence  operations,  had  been  com- 
municated to  the  Secretaries.  The  Council  then  in  office  thought 
the  promises  of  support  which  they  had  receiyed  sufficient  to  justify 
them  in  preparing  the  books  intended  as  the  first  year's  publications 
of  the  Society.  The  volume  of  •  Chemical  Reports  and  Memoirs  * 
was  nearly  ready  for  circulation  at  the  time  of  the  General  Meeting, 
and  its  distribution  was  commenced  soon  afterwards.  The  first 
volume  of  the  translation  of  Gm£lin*s  *  Handbook  of  Chemistiy  * 
has  been  subsequently  completed,  and  this  also  is  now  in  the  hands 
of  members.  While  these  works  have  been  in  course  of  circulation, 
the  Council  have  been  anxious  to  extend  the  limits  of  the  Society, 
with  the  view  of  increasing  the  benefits  to  each  individual  member, 
and  of  promoting  the  general  advantages  resulting  from  a  wider 
diffusion  of  scientific  knowledge. 

"  But,  although  many  new  members  have  been  obtained  within 
the  last  few  months,  some  of  those  whose  names  had  been  in- 
cluded among  the  founders  of  the  Society  have  not  completed 
their  membership,  and  the  numbers  are  yet  insufficient  to  en- 
able the  Council  to  issue  more  than  two  volumes  for  the  first 
year.  They  trust,  however,  it  will  be  satisfactoiy  to  the  members 
to  find  that,  with  their  present  limited  numbers,  one  year's  income 
will  be  nearly  sufficient  to  defray  the  expenses  which  have  been 
incurred  since  1846,  in  founding  the  Society,  advertising  its  ob- 
jects, and  publishing  two  books,  of  which  there  have  been  printed 
several  hundred  copies  beyond  those  required  for  immediate  dis- 
tribution. 


"  In  looking  to  the  prospects  of  the  present  year  (1840),  the 
Council  think  there  is  reason  to  expect  a  considerable  accession  of 
members ;  an  increase  for  which  they  have  prepared,  by  printing  a 
larger  number  of  the  volumes  for  1848  than  have  hitherto  been 
required,  under  the  impression  that  most  new  members  will  desire 
to  possess  the  works  of  the  Society  from  the  commencement. 

"  If  the  increase  of  members  be  commensurate  with  the  expecta- 
tions which  have  been  formed,  the  Council  will  be  enabled  to  issue 
three  books  for  this  year,  including  the  second  and  third  volumes  of 
the  translation  of  Gmeliv's  '  Chemistry,'  which  are  already  in  a 
forward  state  of  preparation.  They  are  gratified  to  find  that  the 
first  volume  of  this  work  has  been  very  favourably  received  by  the 
members  generally,  and  they  doubt  not  that  this  and  the  succeeding 
parts  of  the  translation  will  fully  sustain  the  high  character  which 
the  original  has  for  many  years  borne  as  a  comprehensive  system  of 
chemistry,  and  a  most  valuable  book  of  reference.  Arrangements 
will  be  made  for  completing  this  work  with  as  little  delay  as  pos- 
sible. 

'*  The  selection  of  a  succession  of  suitable  works  for  publication 
by  the  Society  has  repeatedly  engaged  the  attention  of  the  Council, 
who  have  been  desirous,  with  a  due  regard  to  the  principles  upon 
which  the  Association  is  founded,  to  make  its  publications  useful  and 
interesting  to  the  members,  whilst,  at  the  same  time,  they  conduce 
to  the  advancement  of  chemical  science.  Several  years  will  neces- 
sarily elapse  before  the  publication  of  the  translation  of  Gmelin*s 
*  Chemistry '  can  be  completed ;  but  it  is  proposed  that,  during  this 
time,  the  members  shall  receive  at  least  one  volume  each  year  of 
some  other  work.  It  was  decided  that  the  '  Life  and  Works  of 
Cavendish '  would  form  a  suitable  volume  to  be  issued,  in  addition  to 
two  volumes  of  the  '  Handbook*  for  the  present  year,  and  the  Council 
have  accordingly  made  arrangements  to  that  effect  with  t)r.  Wilson, 
of  Edinburgh,  who  has  undertaken  to  prepare  '  A  Sketch  of  the 
Life  of  Cavendish,  a  fiill  discussion  of  the  Water  Question,  and 
abstracts  of  his  other  papers,  with  notes  or  comments  bringing  them 
up  to  the  present  state  of  Chemistxy.' 


*'  Among  other  works  which  have  been  soggested  to  form  single 
Tolumes,  are, 

"  9.  An  abridgment  of  Pebsoz*  work  on  the  Art  and  Theory 
of  Dyeing  and  Calico  Printing,  comprising  the  most  practically  im- 
portant part  of  the  valuable  details  contained  in  the  original  work, 
together  with  a  series  of  illustrations ;  which  Mr.  John  Gbaham,  of 
Manchester,  undertakes  to  edit. 

"  8.  A  Translation  of  the  Essays  of  Saussurb,  on  the  Chemistiy 
of  Vegetation,  together  with  the  Essays  and  Memoirs  of  Hales, 
Inoenbouz,  Ssnkbbibr,  Pbibstlet,  Wibomann  and  Pojustobf,  on 
the  same  subject 

"  Several  works  of  a  more  voluminous  character  have  also  been 
suggested  or  brought  under  the  notice  of  the  Council,  among  which 
are, 

*'  4.  RAincsjU3BEBa*B  '  Dictionary  of  the  Chemical  part  of  Mi- 
neralogy.* 

"  6.  Kopp's  *  History  of  Chemistry.' 

**  6.  A  Bibliography  of  Chemistiy  for  the  present  century,  con- 
taining a  complete  list  of  the  papers  published  on  chemical 
subjects. 

"  7.  Orro's  *  Economic  Chemistiy.' 

*'  8.  Bisohof's  '  Elements  of  Chemical  and  Physical  Geology.' 

"  The  Council  are  convinced  that  there  is  a  great  abundance  of 
matter,  not  otherwise  available  to  the  English  reader,  the  acquire- 
ment of  which,  through  the  agency  of  this  Society,  would  greatly 
benefit  the  working  chemist,  whilst  it  might,  at  the  same  time,  be 
rendered  conducive  to  the  extension  of  a  taste  for  scientific  litera- 
ture. To  ensure  the  full  attainment  of  these  benefits,  however,  it 
will  be  necessary  that  the  limits  of  the  Association  should  be 
extended;  and  it  is  hoped  that  the  members  will  individually 
exert  themselves,  in  co-operation  with  the  Council,  for  effecting  a 
realization  of  the  objects  originally  contemplated  in  the  establish- 
ment of  the  Cavendish  Sociext." 


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The  Segbetaby  stated  that  the  liabilities  of  the  Society  amounted 
to  about  £300,  which  principally  related  to  the  publication  of 
Gicelin's  **  Handbook  of  Chemistiy,"  then  in  course  of  circulation. 
To  meet  these  debts,  they  had  £221  in  hand,  and  there  were  sub- 
scriptions due  for  1848,  not  yet  received  from  the  country,  amount- 
ing to  about  £100.  The  income,  therefore,  would  just  meet  the 
expenditure,  while*  at  the  same  time,  the  Society  possessed  a  large 
stock  of  books  for  supplying  new  members. 

It  was  then  moved  by  Mr.  T.  N.  R  Mobson,  seconded  by  Dr. 
Q.  D.  LoNosTAFF,  and  resolved, 

**  That  the  Report  just  read  be  received  and  adopted." 

The  President  said  that  the  next  business  would  consist  in  the 
election  of  officers  for  the  ensuing  year. 

A  ballot  having  taken  place,  the  following  were  declared  to  have 
been  duly  elected  :— 

llraCfont. 
PiofiBsoa  Gbabax,  F.R.S. 

Vto^VtwOieRts. 


Arthub  Aixin,  Baq.,  F.G.S. 
PBoraasoB  Bbavdi,  F.B.8. 
Babl  of  Bvbldiotov,  F.B.S. 
FBonasoB  T.  Class,  M.D. 
Pbofbssob  Daubbitbt,  F.B.S. 
MicHAXL  Fabaj>at,  D.C.L.,  F.B.S. 


Jacob  Bbll,  Biq. 
GoLDixa  BiBD,  M.D.,  F.B.S. 
BiFJAxnr  0.  Bbodib,  Baq. 
Wabbbh  Dblabvb,  Esq. 
J.  P.  Gabsiot,  Esq.,  F.B.S. 
J.  J.  QBXWYa,  Biq. 
T.  H.  Hbvbt,  Biq.,  F.B.S. 

A.  W.  HOFMAIB,  P11.D. 


Bbv.  Wm.  YiBHOir  Habooubt,  F.&.S. 
Sib  B.  Kabb,  M.D.,  M.B.I.A. 

ThB  MaBQUIS  OV  NOBTBAMPTOir,  F.&.S. 

BioHABD  Phillips,  Biq.,  F.B.8. 
WiLLiAK  Pboux,  M.D.,  F.B.S. 
Jambs  Thoiuoh,  Bsq.,  F.B.8. 

Conned. 

a.  D.  LOBOflfABT,  M.D. 

W.  A.  MiLLBB,  M.D.,  F.B.S. 
JoHATHAB  Pbbbiba,  M.D.,  F.B.8. 
Ltob  Platvaib,  P1i.D.,  F.B.8. 
Bdhitbd  Bohalss,  Ph.D. 
Bobbbt  Wabibotov,  Biq. 
Albbbd  Wbitb,  Bm|.,  F.L.8. 
Colobbl  p.  ITOBZB. 


CTrfSSUtlt. 
HflBBT  Bbauvobt  Lbbsob,  M.D.,  8t  Thomas'i  Hospital. 

Thbophilus  Bbdwood,  Bsq.,  19,  Hontagae  Street,  BatseU  Sqoare.